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TheThorn
2005-Jul-28, 11:18 PM
The following post appeared on the Minor Plante Mailing List today, from Jose-Luis Ortiz:



"Hi there,

We found a very slowly moving object while carrying out a checking of some of
our oldest images from the modest TNO survey that we started in 2002.
http://www.iaa.es/~ortiz/OSNTWeb/index.htm
The object was very bright in our images (m_V~17.6!!) so we were able to precover it, and also recover it.

According to our best orbit fit and using regular assumptions on phase angle
correction, the H value es around 0.3. Unfortunately we do not know the
geometric albedo but if below 0.25 (which is the case of all TNOs for which an
albedo has been measured except Pluto), the object would be larger than Pluto.
However, it may well happen that this object is abnormally bright (with a very
high albedo), like Pluto. So, depending on the albedo, this object might be sort
of a Pluto's brother or Pluto's father...

This object is beyond Pluto and almost reachable by most amateurs, which is the
reason why we write here!. It is observable right after sunset for a while at a
reasonable elevation. Maybe some decent science can still come out of your
observations.

Enjoy it!.

Our findings have been sent to the MPC, but the object has not received a
provisional designation yet. Some ephemeris are given here

Ephems (geocentric) [Date, RA, Dec, r, delta, elongation, mag]:
20050728.00000 13 21 50.208 +20 7 53.62 51.605 51.239 68.32 17.47
20050729.00000 13 21 51.856 +20 7 14.56 51.619 51.239 67.49 17.47
20050730.00000 13 21 53.576 +20 6 35.29 51.632 51.239 66.66 17.47
20050731.00000 13 21 55.369 +20 5 55.81 51.646 51.238 65.84 17.47
20050801.00000 13 21 57.233 +20 5 16.13 51.659 51.238 65.01 17.47
20050802.00000 13 21 59.169 +20 4 36.26 51.672 51.238 64.19 17.47
20050803.00000 13 22 1.176 +20 3 56.23 51.685 51.238 63.37 17.47
20050804.00000 13 22 3.253 +20 3 16.02 51.698 51.238 62.55 17.47
20050805.00000 13 22 5.401 +20 2 35.67 51.711 51.238 61.73 17.47
20050806.00000 13 22 7.619 +20 1 55.17 51.723 51.238 60.92 17.47
20050807.00000 13 22 9.906 +20 1 14.54 51.736 51.238 60.11 17.47
20050808.00000 13 22 12.261 +20 0 33.79 51.748 51.238 59.29 17.47
20050809.00000 13 22 14.685 +19 59 52.93 51.760 51.238 58.49 17.47
20050810.00000 13 22 17.176 +19 59 11.97 51.772 51.237 57.68 17.47
20050811.00000 13 22 19.734 +19 58 30.93 51.784 51.237 56.88 17.47


The orbital elements are:

OSNT11
Epoch 2005 July 29.0 TT = JDT 2453580.5
M 197.97485 (2000.0) P Q
n 0.00345428 Peri. 239.53682 +0.91285785 -0.07597426
a 43.3408541 Node 121.89008 +0.13526717 +0.98332108
e 0.1887862 Incl. 28.19395 -0.38521856 +0.16524998
P 285.33 H 0.2 G 0.15 U 2


This is potentially very big news.

StarLab
2005-Jul-28, 11:22 PM
And after all this, all the astro-liberals refuse to let everyone else drop Pluto's status as a Planet. Tut-tut... -_-

Jakenorrish
2005-Jul-29, 10:25 AM
http://news.bbc.co.uk/1/hi/sci/tech/4726733.stm

Pluto should remain a planet as it was designated a planet at the time. Does the discovery of different types of extrasolar planets 5 times the size of Jupiter orbiting their parent stars within 5 days mean we're going to have to re-evaluate the Earth's status as a planet? No.

Pluto historically is a planet. You can't re-write history and as such this is a good enough reason for it to remain a planet. Even if we discover new larger objects further out. But that's for another thread I reckon!

antoniseb
2005-Jul-29, 01:18 PM
Originally posted by StarLab@Jul 28 2005, 11:22 PM
all the astro-liberals refuse to let everyone else drop Pluto's status as a Planet.
I'm sure the conversation will come up again. Just as it does here. Changing or keeping Pluto's "status" is not a question of whether things are exactly as they seem. Perhaps your biggest worry is having to change your memorized string of planet-names.

John L
2005-Jul-29, 03:25 PM
Originally posted by Jakenorrish@Jul 29 2005, 04:25 AM
http://news.bbc.co.uk/1/hi/sci/tech/4726733.stm

Pluto should remain a planet as it was designated a planet at the time. Does the discovery of different types of extrasolar planets 5 times the size of Jupiter orbiting their parent stars within 5 days mean we're going to have to re-evaluate the Earth's status as a planet? No.

Pluto historically is a planet. You can't re-write history and as such this is a good enough reason for it to remain a planet. Even if we discover new larger objects further out. But that's for another thread I reckon!
Ceres and Vesta should be planets based on your arguement. When they were first discovered between Jupiter and Mars they were called planets, too. After discovering several in that same orbital area, though, and after Jupiter had moved to being the 11th planet, however, it was decided that these objects needed a new designation and were called asteroids. So, should we have 100,000's of planets between Mars and Jupiter, and 100,000's more past Neptune, or should we give these objects that share the same orbital area a new designation, too? Pluto is not a planet!

TheThorn
2005-Jul-29, 05:36 PM
This object has been given a designation: 2003 EL61. A number of people are currently combing archives of sky images looking for (and finding) pre-discovery images of it that have already allowed them to nail it's orbit quite well. It's currently at about 52 AU from the sun, (Pluto averages 39 or so). It comes in as close as 35.

Apparently, Brown, Trujillo, and company (the people who brought you Sedna) have been watching this one for a while, and not telling anyone. They had published abstracts of papers that they will be publishing in the next couple of months about the object, but no positional data, and by the time the papers will be published, the object will be placed too close to the sun for anyone else to observe it. This is exactly what these guys did with Sedna, which really annoyed the rest of the Minor Planet community. This time they got caught. Ortiz found it in the meantime, and he is getting credit for the discovery, since he's the first one to publish positional information (in the quantity required for discovery credit).

The abstracts of the papers from the other group here (http://www.aas.org/publications/baas/v37n3/dps2005/320.htm) and here (http://www.aas.org/publications/baas/v37n3/dps2005/786.htm) indicate that water ice has been detected on the object, that it has a satelite, and that the mass of the entire system (object and satelite) is about 30% of Pluto's mass.

So it must be pretty reflective to be that bright and that small.

And Pluto's place as the biggest TNO is safe.

jas2000
2005-Jul-29, 08:05 PM
http://news.bbc.co.uk/go/pr/fr/-/1/hi/sci/...ech/4726733.stm (http://news.bbc.co.uk/go/pr/fr/-/1/hi/sci/tech/4726733.stm)


Astronomers have found a large object in the Solar System's outer reaches. It is being hailed as "a great discovery".
Details of the object are still sketchy. It never comes closer to the Sun than Neptune and spends most of its time much further out than Pluto.

It is one of the largest objects ever found in the outer Solar System and is almost certainly made of ice and rock.

It is at least 1,500km (930 miles) across and may be larger than Pluto, which is 2,274km (1,400 miles) across.

The uncertainty in estimates of its size is due to errors in its reflectivity.

It might be a large, dim object, or a smaller, brighter object. Whatever it is, astronomers consider it a major discovery.

In 2004 scientists discovered Sedna, a remote world that is 1,700 km across.

antoniseb
2005-Jul-29, 11:23 PM
Actually this object is inside Sedna's orbit, but mostly outside Pluto's orbit. It is currently 51 AU away from the Sun.

RUF
2005-Jul-30, 01:01 AM
Today is the first time I saw an artucle about the "10th Planet":

LOS ANGELES (AP) ó Astronomers announced Friday that they have discovered a new planet larger than Pluto in orbit around the sun. The discovery in the outlying regions of solar system was made with the Samuel Oschin Telescope at the Palomar Observatory.

The unnamed planet would be the 10th in the solar system, although there are scientists who dispute the classification of Pluto as a planet.

The discovered object is the farthest-known object in the solar system, Caltech said in a statement. Its location is currently 97 times the distance between the sun and Earth.

Brown made the discovery with colleagues Chad Trujillo of the Gemini Observatory and David Rabinowitz of Yale University.

The object was first photographed on Oct. 31, 2003, but it was so far away that its motion was not detected until data was analyzed again this past January. The scientists have since studied the object over the past seven months.

"It's definitely bigger than Pluto," Brown said in a statement.

He said scientists are "100% confident that this is the first object bigger than Pluto ever found in the outer solar system."

The research was funded by NASA.
--------------------------------------------------------------------------------

Sounds like they're on to something!

TheThorn
2005-Jul-30, 01:53 AM
And it heats up.

Brown et al., apparently afraid that they might lose credit for yet another large KBO discovery, (after losing credit yesterday for 2003 EL61) have provided positional data on two more of them, one of which (2003 UB313) is estimated by some as 4400 km to 9900 km in diameter.

This one almost certainly IS bigger than Pluto, is currently 96 AU from the sun (averages 67, so it comes in almost to Neptune's orbit at some points). Its orbit is inclined 44 degrees to the ecliptic.

Both these objects are Scattered Disk Objects - nothing really strange about their orbits, unlike Sedna.

But with something bigger than Pluto out there, the "planet" definition debate is certainly about to heat up again.

See
Planet Lila (http://www.gps.caltech.edu/~mbrown/planetlila/index.html), and this BBC story (http://news.bbc.co.uk/2/hi/science/nature/4730061.stm), and this one from NASA. (http://www.nasa.gov/home/hqnews/2005/jul/HQ_05209_10th_Planet.html)

Dave Mitsky
2005-Jul-30, 02:37 AM
An even larger one, 2003 UB313, was announced shortly afterwards. It may be twice as large as Pluto and is three times more distant. This should shake planetary science up a bit.

http://www.space.com/scienceastronomy/0507...new_planet.html (http://www.space.com/scienceastronomy/050729_new_planet.html)

http://www.gps.caltech.edu/~mbrown/planetl...lila/index.html (http://www.gps.caltech.edu/~mbrown/planetlila/index.html)

Dave Mitsky

Dave Mitsky
2005-Jul-30, 03:40 AM
The discovery of a third trans-Neptunian object, 2005 FY9, has also been announced. It has a magnitude of 17.4 and is 52 AU distant.

Dave Mitsky

Matthew
2005-Jul-30, 11:04 AM
Ah good for astronomy. Now they can write papers on what a Planet is. Because if we don't class these new objects planets then there is no reason for pluto to be a called a planet (besides the nostalgic value).

qraal
2005-Jul-30, 12:41 PM
Hi

The Spitzer results mean it's probably less than ~ 2,000 miles across. The 4400 km and 9900 km figures you quote are extremely unlikely - but objects that big very likely exist even further out. Oligarchic planet formation models - major planets formed via multiple mergings of many smaller objects they co-existed with and scattered - such imply that many, many Mars-to-Earth sized objects are out there somewhere this side of the Oort Cloud (i.e. 100 - 1000 AU away.)

And watch out for another planet soon.... 2003 UB313 is magnitude -1.1, but 2005 FY9 is ~ -0.4, even brighter than yesterday's 2003 EL61 and not much dimmer than today's. Different albedos might mean 2005 FY9 is bigger!

qraal

Fraser
2005-Jul-30, 03:32 PM
SUMMARY: Astronomers have discovered a new planet orbiting our Sun, which is larger than Pluto. It's located 97 times further than the Earth from the Sun. This new, 10th planet was actually first photographed in 2003 by the Samuel Oschin Telescope at Palomar Observatory, but it took this long to study and confirm its size and orbit. A name has been proposed to the International Astronomical Union, which is making its decision.

View full article (http://www.universetoday.com/am/publish/10th_planet_discovered.html)

What do you think about this story? Post your comments below.

alfchemist
2005-Jul-30, 03:59 PM
Seems like there's a great possibility that many KBO would be classified as planets by their sheer size. Would this make a belt of planets? Sounds weird

Greg
2005-Jul-30, 04:05 PM
Quite an exciting day for us astronomers as the Cal Tech team fianlly coughed up its secrets from its powerful all-sky survey. I am not sure why they didn't announce their earlier finding that the Spanish team independently found a few days ago. As a result of that find they got nervous and published their other 2 KBO findings with this one being the biggest. Quite a story indeed, hopefully they are hoarding other discoveries as well to excite us later.
These 3 findings do not surprise me at all, however. Recall that Triton is the largest moon by diameter at 2700km and it orbits Neptune. When they were speculating as to the potential sizes of KBOs yet to be found, I realized that they could be as big as or even bigger than Triton, as this appears to be. The estimated diameter is around 2700 to 3000km making it bigger than any known moon and larger in diameter (not by mass) than Mercury, so I agree that it should be defined as a planet according how we currently define them. For comparison Mars measures in at about 3300 km in diameter.
However, I am and have been an advocate for restructuring the classifications system for objects in the solar system and I beleive both Pluto and this object should be defined as KBOS and not planets. But that is another story.
In the next few years even more powerful tlescopes (such as the Discovery Channel tlescope (5.4m) and one other larger scope) will see first light that will be dedicated to all-sky surveys like the ones that found these objects. Alot of theorists believe that mars-sized objects will be found much further out than the KBOs at around 500-1000 AU.

Eric Ryan
2005-Jul-30, 04:33 PM
They ought to name this one "Goofy" for its excentric orbit.

www.ryanrodco.com

TheThorn
2005-Jul-30, 05:21 PM
I think it has already been established that 2003 UB313 is bigger than Pluto. From the Nasa press release linked to above:



"It's definitely bigger than Pluto," said Brown, who is a professor of planetary astronomy.

Scientists can infer the size of a solar system object by its brightness, just as one can infer the size of a faraway light bulb if one knows its wattage. The reflectance of the planet is not yet known. Scientists can not yet tell how much light from the sun is reflected away, but the amount of light the planet reflects puts a lower limit on its size.

"Even if it reflected 100 percent of the light reaching it, it would still be as big as Pluto," says Brown. "I'd say it's probably one and a half times the size of Pluto, but we're not sure yet of the final size.

"We are 100 percent confident that this is the first object bigger than Pluto ever found in the outer solar system,Ē Brown added.


The Spitzer results limit it to 3000 km across at most, but the optical results make it at least 2400 km (Pluto's diameter). The 4400 to 9900 km numbers were based on the typically accepted range of albedos for normal KBOs. This one obviously has a higher albedo than most, as does Pluto.

You're right that the albedo is the only way to determine size for a single object if the disk cannot be resolved. So 2005 FY9 also announced yesterday could, just possibly, be larger, (depending on its albedo) but that is unlikely. Same goes for 2003 EL61 announced the day before by Ortiz.

Three large KBOs in 24 hours. Remarkable, eh? Not really. Brown et al. have been watching these three objects for months in secrecy, got scooped on one, and got scared that they'd get scooped on the other two. They hinted about a "hacker" in a press conference yesterday. That story is also interesting:

After Ortiz had announced 2003 EL61, several people on the Minor Planets Mailing List commented that it must be K40506A, the internal designation that Brown et al were using for the object, and had mentioned in the abstracts of a couple of papers they were about to publish. If you did a google on "K40506A" at that point (I did) you would find references to it, including positional information, in rather cryptic internal documents from Yale and Ohio state (see here.) (http://www.google.ca/search?hl=en&q=K40506A&btnG=Google+Search&meta=)
It appears they were unintentionally leaking their own data.

A member of the list apparently did some searches on other possible internal references (knowing how they structure those designations makes it pretty easy) and came up with publically available data on the locations of the objects that were later designated 2005 FY9 and 2003 UB313 as well. So Brown and company announced them before some amateurs could make their own observations and get credit for the discoveries, and blamed a "hacker". Googling data that they had (perhaps unintentionally) made public, does that count as "hacking"?

It is an interesting contrast between how the amateur community handles these things, and how the pros do it. There is a lot of grant money out there that depends on having good things to study, so when the pros find something interesting, some of them will keep it to themselves, until they can collar the grants. An amateur might keep something to himself for one day (because to get credit you have to have observations from two nights), but that's about it.

Galactus
2005-Jul-30, 06:05 PM
Well, this discovery should certainly get the conspiracy theorists and alternate scientists going. Based on ancient Sumerian documents, etc., they have always maintained that another planet existed, one with a very large eccentricity and a very large period of revolution.

Rats!! Does this mean some of their other theories are right too? (That humans were genetically engineered by advanced being from another planet?) If so, I guess we have some interesting times to look forward to.

CharlesBell
2005-Jul-30, 06:07 PM
Astronomers at Palomar Observatory Discover a 10th Planet Beyond Pluto + images of 2003 UB313
http://www.gps.caltech.edu/~mbrown/planetl...lila/index.html (http://www.gps.caltech.edu/~mbrown/planetlila/index.html)


Gemini Observatory Shows That "10th Planet" Has a Pluto-Like Surface
http://www.gemini.edu/index.php?option=con...ask=view&id=142 (http://www.gemini.edu/index.php?option=content&task=view&id=142)

Mike Brown's group paper on the discovery of a moon around 2003 EL61
http://www.gps.caltech.edu/%7Embrown/paper...ers/ps/EL61.pdf (http://www.gps.caltech.edu/%7Embrown/papers/ps/EL61.pdf)

2003 EL61 + images
http://www.gps.caltech.edu/~mbrown/2003EL61/

The homepage of Chad Trujillo:
http://www.gps.caltech.edu/~chad/

The homepage of Mike Brown:
http://www.gps.caltech.edu/~mbrown

Ephemerides for the new TNOs

MPEC 2005-O41 (2005 July 29)
2003 UB313
http://cfa-www.harvard.edu/mpec/K05/K05O41.html


MPEC 2005-O36 (2005 July 29)
2003 EL61
http://cfa-www.harvard.edu/mpec/K05/K05O36.html


MPEC 2005-O42 (2005 July 29)
2005 FY9
http://cfa-www.harvard.edu/mpec/K05/K05O42.html

antoniseb
2005-Jul-30, 07:01 PM
Thanks for collecting these Charles.

imported_alan
2005-Jul-30, 08:14 PM
The size of the planet is limited by observations using NASA's Spitzer Space Telescope, which has already proved its mettle in studying the heat of dim, faint, faraway objects such as the Kuiper-belt bodies. Because Spitzer is unable to detect the new planet, the overall diameter must be less than 2,000 miles, said Brown.Is this because its not big enough to be detected or because its to reflective and therefore too cold to be detected?

Greg
2005-Jul-30, 08:16 PM
The KBOs were likely made from the same building blocks as the other planets but formed in the outer solar system. As Neptune invaded their space from the inner solar system as it moved outward, the kbos were scattered into longer and more eccentric orbits by their interaction with Neptune. One of their characteristics is that generally their elongated orbits cross near Neptune's orbit at their minimum, indicating that it was Neptune that threw them out into their current orbits.
Sedna defies this trend somewhat in that its orbit is not inclined and remains in the same plane with the planets, but it is elongated. The reason alot of models predict larger planets 500-1000 AU is related to this. Since Neptune is a smaller planet, small bodies encountered by it only got thrown out as far as the Kuiper belt. In the case of Jupiter, any bodies it threw could easily be orbiting at 500-1000 AU distances if they were not thrown into interstellar space entirely.

Dave Mitsky
2005-Jul-30, 08:48 PM
The article at http://skyandtelescope.com/printable/news/...rticle_1563.asp (http://skyandtelescope.com/printable/news/article_1563.asp) gives a visual perspective of the sizes of the various TNOs.

Dave Mitsky

Dave Mitsky
2005-Jul-30, 08:52 PM
Some relevant data:

2005 FY9 has a magnitude of 17.4 and is 52 AU distant.

2003 EL61 has a magnitude of 17.7 and is also 52 AU away.

2003 UB313 shines at 18.9 magnitude from a distance of 97 AU.

Dave Mitsky

TheThorn
2005-Jul-30, 09:20 PM
Here's another link, to a Space.com (http://www.space.com/scienceastronomy/050729_new_planet.html) story that starts the discussion on what is a planet.

Myself, I think eventually we're going to relegate the term "planet" to an historical reference to 9 objects, and start referring to these objects with more than one classification.

Pluto and the other KBO's top out at least an order of magnitude smaller in mass than Mars, the smallest terrestrial planet.

The terrestrial planets top out (with Earth the largest) over an order of magnitude smaller in mass than Uranus, the smallest of the gas giants.

Clearly we've got at least three types of objects here, Gas Giants, Terrestrial planets, and KBO's. Asteroids are also different, with the biggest of them a couple of orders of magnitude smaller than the biggest KBO's.

I think, if you look at the question of composition, you have two types of objects, gassy (or icy if they're cold) and rocky. This probably depends on where they formed.

Each of them comes in two flavours, major and minor. The difference between gassy and rocky is easy, and the difference between major an minor is even more obvious when you look at it within one of those groups: the biggest minor rocky object (Ceres) is over a thousand times smaller in mass than the smallest major rocky object (Mars), and the largest minor gassy object (Ganymede) is over 1,000 times smaller in mass than the smallest major gassy object (Uranus).

All the KBOs, including Pluto and these latest ones, are minor gassy objects. So are all comets.

The only object in the solar system that doesn't clearly fit in one of these categories is our moon (it is in between major rocky and minor rocky), and its origin has been a puzzle for decades - it clearly is was not formed in the same way as other objects.

slotdrag
2005-Jul-31, 12:22 AM
Ok if this is the tenth planet what happened to sedena? wouldnt this be the eleventh planet? Im lost whos counting? When does this become official? How does it become official?

astronomy2004
2005-Jul-31, 12:38 AM
sedna is smaller than pluto so they're considering anything bigger than pluto a planet.

slotdrag
2005-Jul-31, 03:34 AM
Who are they?

slotdrag
2005-Jul-31, 03:36 AM
Ok if this is the tenth planet what happened to sedena? wouldnt this be the eleventh planet? Im lost whos counting? When does this become official? How does it become official?

astronomy2004
2005-Jul-31, 03:40 AM
the scientists that get to decide the faith of the objects out there.

wether they're plaetoids or what.

don't mean to stir up trouble. it's just my opinion on how they decide. should have clarified that.

Planetwatcher
2005-Jul-31, 05:13 AM
Recall that Triton is the largest moon by diameter at 2700km and it orbits Neptune.
At the risk of bearing bad news, Triton is NOT the largest moon by diameter.
That honor belongs to Ganymede of Jupiter, which is 5,280 Km.
Followed by Titan of Saturn which is 5,120Km. Both of which are larger then planet Mercury's just above 5,000 Km.

The next two in line are back at Jupiter with Calllisto and Io which are respectively 4,866 Km and 3,640 Km. Then comes our Moon which is 3,476 Km, before one more return to Jupiter for Europa which is 3,000 Km. on the nose.

Finally we get to Triton's 2,700 Km. diameter which is followed by Pluto's 2,320 Km.
The next dozen plus bodies alternate between moons of Saturn, Uranus, Pluto, and KBOs.

To the best of my understanding and excluding the latest findings the next 15 bodies decending in size are in the following order.

Titania of Uranus
Rhea of Saturn
Oberon of Uranus
Sedna in Kupier belt
Iapetus of Saturn
2004 DW in Kupier belt
Charon of Pluto
Quaoar in Kupier belt
Umbriel of Uranus
Ariel of Uranus
Dione of Saturn
Ixion in Kupier belt
Tethys of Saturn
Varuna of Kupier belt
Ceres of the asteroid belt between Mars and Jupiter

The newest discoveries will drasticly change the order.

Planetwatcher
2005-Jul-31, 05:27 AM
Hey guys, I just did some math, and if the newly discoverd 10th planet is 50% larger then Pluto like the discoverers say is possible, then it would be nearly the same size as our moon.
Any larger and it could fall between Io and our Moon, or Io and Callisto.

If it is 25% larger, then Pluto then it will fall between Europa, and Triton.

Even if it is only 15% larger then Pluto, it will nearly match Triton.

This could greatly change the order of things we thought we knew.

Planetwatcher
2005-Jul-31, 05:50 AM
Sedna is not currently considered a planet. :huh:
However the new discoveries could change that status. B)
Especially if a second of the three new KBOs is at least near the size of Pluto.
That would make 3 near Pluto sized objects considered to be planets.
Which would bring about a third classifacation of planets. B)

The first being the rocky terristrial like inner planets. We have four of them. Second is the gasious like giant middle planets. There are four of them as well.
If there is discovered, at least one more Pluto size object, then we have again at least three of the same. This time being large rocky outer planets. Which in that case Sedna has good potentual to be considered the fourth in that group. ;)

We already know from studying the exo-planets, that our solar system's arraingment of gas giants in the middle or outer parts of the star system is more the exception to the rule then the rule. :D

This again makes it a little easier for the scientific community to accept the notion of changing what we thought we knew about our universe. <_< :o

RUF
2005-Jul-31, 06:30 AM
I didn&#39;t know that Ganymede was considerd a "Gassy object." How can that be so?

other than that, I agree with what you said. I&#39;ve been mulling over that whole size vs. mass. vs composition thing myself. wondering: "what exactly is a planet, and is Pluto a planet?"

I meant that as a rhetorical question... I don&#39;t mean to heat that old classic aguement up again, but it is fun to kick it around in yer brain&#33; :lol:

Greg
2005-Jul-31, 07:03 AM
I stand corrected. In all of the excitement I posted the radii and not the diameter of all of the objects aside from Triton. That makes Triton and this KBO about 1/2 as large as the larger moons (Titan, Ganymede, Io, Luna(our moon)) and Mercury. I had meant to draw the comparison between Triton&#39;s size and the size of the larger KBOS before I got sidetracked quickly posting radiii instead of diameters before I ran off to work.
This does again highlight the oddity of calling an object smaller than alot of moons a planet, a mistake I would not repeat if I were on the commission, bit one they will probably allow in this case. Thanks for the painstaking work of posting all of those diameters, it is nice to compare these objects with some perspective. MArs would be about 6600km in diameter. Planets of this size or larger are theorized to exist 500-1000 AU out.

Planetwatcher
2005-Jul-31, 07:14 AM
Leave it to Dave to save the day.
What we have here is three different major discoveries, so let&#39;s get them straight.

1, The one called 2005 FY9 is nearly twice the distance of Pluto and is proabley at least the size of Pluto, and maybe a little larger.

2, The one called 2003 UB313 is the farthest, at over three times the distance of Pluto. It is also billed as the largest of the three. It is calculated to be at LEAST the size of Pluto, and perhaps up to 50% larger. That makes it the same size as our Moon.

3, The one called 2003 EL61 is about the same distance as the first one above.
Quite likely the smallest of the three, but still is at least bigger then Sedna, and perhaps even as large or slightly larger then Pluto.
In addition, this one has a moon which is around a third of the size of Pluto, and orbits it&#39;s parent 2003 EL61 in 49 days.

Perhaps we can get someone out there to write an article which compairs all three and hopefully eleminate some confusion.

Planetwatcher
2005-Jul-31, 08:47 AM
Thorn; I feel the need to correct you on a few minor points. Although minor, I don&#39;t want you to feel dumb, but the facts need to be correct.

Mars, the smallest terrestrial planet.
Actually Mercury is the smallest terrestrial planet. It is significantly smaller then Mars.


Uranus, the smallest of the gas giants.
Neptune is the smallest of the gas giants although not by much.


the biggest minor rocky object (Ceres) is over a thousand times smaller in mass than the smallest major rocky object (Mars),
The astreroid Ceres is 960 x 932 km. in diameter. Mars is about 4222 miles (6790 km) in diameter, like I said, Mercury is smaller it is 3032 miles (4880 km).
The difference in size is way less then a thousand times.

Ceres is more like 480 times smaller then Mercury.


and the largest minor gassy object (Ganymede) is over 1,000 times smaller in mass than the smallest major gassy object (Uranus).

I never heard of minor gassy objects, and certainly not Ganymede as anything like that. In fact Ganymede doesn&#39;t even have an atmosphere, although it is the largest of all moons, even larger then Titan, which does have an atmosphere.

And again, Neptune is smaller then Uranus.


All the KBOs, including Pluto and these latest ones, are minor gassy objects. So are all comets
This is perhaps the bigest error of all.
There is no gas associated with KBOs other then we know that Pluto has an atmosphere, and are pretty sure that Charon, and Sedna have atmospheres as well. Although they are frozen atmospheres.

No comet is known to have an atmosphere. They are made of rock, and snow like material. When they come close to the Sun, the snow is vaporized, but that doesn&#39;t make it a gassy object, because if the Moon were subjected to a comet like orbit, parts of it would vaporize as well and make a tail. Although not to the extent of a comet.

Your whole posting really has no supporting facts, although you do make some valid points.

Myself, I think eventually we&#39;re going to relegate the term "planet" to an historical reference to 9 objects, and start referring to these objects with more than one classification

Clearly we&#39;ve got at least three types of objects here, Gas Giants, Terrestrial planets, and KBO&#39;s. Asteroids are also different

In the end we will most likely have three catagories of major planets.
1, Gas giants,
2, Rocky inner planets,
3, Large KBOs,

As for minor planets
1, Asteroids, (In the main belt)
2, Asteroids, (Near Earth, and/or Trojen)
3, Asteroids, (Centaurs) [other then the two above, but closer then Neptune]
4, Smaller KBOs

Then the moons which have several catagories as well.
Seven are smaller then Mars, but bigger then Pluto, 5 of which are smaller then Mercury as well.
Nine are smaller then Pluto, but larger then Ceres.
Seven more are smaller then Ceres but larger then Juno (the 4th largest asteroid).
Moons of asteroids, and Kupier objects.
Moons of moons.
Shepherd moons.
Of all the moons, at least 6 have atmospheres.

Then of coarse there are comets.
I don&#39;t think I missed anything.

Planetwatcher
2005-Jul-31, 09:50 AM
Your welcome for the stats.
Actually I had all the moons on hand already.
Opening two additional windows and accessing two sites gave me the rest..

Perhaps I stand corrected as well.
This was the first thread I entered concerning the new finds. It appears we have two additional threads currently going as well which are somewhat related.

There are currently three newly discovered KBOs. Two are proclaimed as being bigger then Pluto or at least as big.
Perhaps up to the size of our Moon.
The third one claims to be at least bigger then Sedna, perhaps slightly bigger then Pluto. But it brags of a moon, which the other two do not.

So of the last 15 I listed, one of the KBOs may displace in the top three.
The other two will come in somewhere between Io, and Pluto which could affect the placement of one or more of the following.

13, Io
14, Luna, Our moon
15, Europa
16, Triton
17, Pluto

Before these finds Pluto was the 17th largest body in the Solar System.
Now it may barely stay in the top 20.

Sometime after we get in the results, I&#39;ll post in order the 50 largest Solar System bodies. That should prove to be pretty cool.

Nereid
2005-Jul-31, 01:19 PM
Originally posted by Greg
The reason alot of models predict larger planets 500-1000 AU is related to this.
Planets of this size or larger are theorized to exist 500-1000 AU out.
Do you have a source for this Greg?

om@umr.edu
2005-Jul-31, 01:22 PM
This is great news, Fraser.

Thanks for bringing us this story.

I look forward to additional information on the composition of this new object.

With kind regards,

Oliver

lccrmt
2005-Jul-31, 02:32 PM
I am not an astronomer so please forgive my ignorance if this question seems silly but... How is it that we can photograph distant galaxies and stars and get pretty good pictures yet we can&#39;t get a good pic of Pluto and completely missed this new planet even though these things are a lot closer to us? This confuses me.

Greg
2005-Jul-31, 03:34 PM
Nereid, yes the source I used is from Newscientist, Jul 23-29, p. 29-32,
The principal theorist they interviewed was Eugene Chiang at the Univ of Cal-Berkley.

rocketblair
2005-Jul-31, 03:47 PM
Finally, a KBO larger than Pluto&#33; It seems to me there should be 8 "planets" in our solar system, and this number would not change after any new discovery.

1-4 The four inner planets
5-8 The four gas giants

Pluto, Sedna, Quoror, Varuna, Ixion, and all the other icy bodies outside the gas giants regardless of size should not be added to the "planet" count. If Mars size or even larger objects are discovered, they would be KBO&#39;s also, or OCO&#39;s if they are found in the Ort cloud. We are just beginning to get a grip on the outer solar system, so classification should be kept reasonably simple for now. What needs to happen is for the Pluto Lovers to let go of historical comfort and move on. If Pluto remains a Planet, then we get a 10th, 11th, 12th... Pluto&#39;s place in the history of astronomy would be greatened by reclassification. In addition to the 70+ years of it being understandably considered a planet, it would always remain the closest KBO to Earth. With more and more large bodies being discovered, the alternative is having who knows how many more "planets" added after Pluto. This would be a travesty to science in my opinion, thanks for considering it.

TheThorn
2005-Jul-31, 05:41 PM
Thorn; I feel the need to correct you on a few minor points. Although minor, I don&#39;t want you to feel dumb, but the facts need to be correct.

I always stand ready to be corrected, but you should read a little more carefully before you start correcting.


Actually Mercury is the smallest terrestrial planet. It is significantly smaller then Mars.

You are absolutely correct, and I stand corrected on that point. Mercury is about half the mass of Mars. My mistake, and I don&#39;t know how I managed to forget Mercury, but it doesn&#39;t change my conclusions at all. The other differences I pointed out are many times that large.


Neptune is the smallest of the gas giants although not by much.

Sorry, but it is not. Uranus is the least massive of the gas giants, at 8.6 * 10^25 kg. Neptune is about 20% more massive at 1.0*10^26 kg. Mass is obviously a better indicator of size than diameter in this discussion - otherwise a neutron star is a minor object compared to a planet. All through my note I was careful to repeat that I was using mass when I referred to size.



Ceres is more like 480 times smaller then Mercury.

This is true. You appear to have used mass here, rather than diameter. Good. The point remains, there is a HUGE, unmistakable difference between major and minor.




and the largest minor gassy object (Ganymede) is over 1,000 times smaller in mass than the smallest major gassy object (Uranus).

I never heard of minor gassy objects, and certainly not Ganymede as anything like that. In fact Ganymede doesn&#39;t even have an atmosphere, although it is the largest of all moons, even larger then Titan, which does have an atmosphere.

The term gassy object was my own. I said:

I think, if you look at the question of composition, you have two types of objects, gassy (or icy if they&#39;re cold) and rocky. This probably depends on where they formed.


Things in the solar system seem to come in two types, ones that contain materials that are gases at temperature you&#39;d find here on earth (I DID point out that they are ices at lower temperatures) and things that are made up primarily of stuff that&#39;s solid at our temperatures. I probably should have been clearer on that point, but referring to the gas giants as "icy" would have been just as confusing as referring to Ganymede as "gassy". The distinction is in the composition, not the temperature.


This is perhaps the bigest error of all.
There is no gas associated with KBOs other then we know that Pluto has an atmosphere, and are pretty sure that Charon, and Sedna have atmospheres as well. Although they are frozen atmospheres.

I DID say icy as an equivalent. It really was there, if you would have read a little more carefully. (Sorry if I&#39;m getting defensive).


Your whole posting really has no supporting facts, although you do make some valid points.

I don&#39;t know, Planet, other than the gaff about Mercury, I stand by everything in that post. I think the facts certainly DO support the idea.

Your taxonomy seems somewhat arbitrary to me. What&#39;s the difference between "Large KBOs" and "Small KBO&#39;s"? They&#39;re all minor gassy (or icy) objects. And if they get purturbed into the inner solar system, they become comets. NEOs are just main belt asteroids that have been perturbed into orbits that come close to the earth. And Centaurs are not likely to be asteroids, but rather KBOs that have been perturbed into the current unstable orbits - they are guaranteed to be perturbed back out of those orbits (by an encounter with a gas giant), either to become comets or Oort Cloud objects.

My taxonomy was free from any reference to orbit. That&#39;s because I don&#39;t think the same object should change categories just because it has an encounter with another object that changes it&#39;s orbit.

TheThorn
2005-Jul-31, 05:53 PM
Originally posted by Planetwatcher@Jul 31 2005, 07:14 AM
3, The one called 2003 EL61 is about the same distance as the first one above.
Quite likely the smallest of the three, but still is at least bigger then Sedna, and perhaps even as large or slightly larger then Pluto.
In addition, this one has a moon which is around a third of the size of Pluto, and orbits it&#39;s parent 2003 EL61 in 49 days.

Actually, it&#39;s the system of 2003 EL61 and its satelite combined that is 30% of the mass of Pluto. Since the satelite is less than 1% of the primary in this case, that means that EL61 itself is less than 1/3 the mass of Pluto (making it about 70% of the diameter, if they are the same density).

bossman20081
2005-Jul-31, 05:59 PM
I am not an astronomer so please forgive my ignorance if this question seems silly but... How is it that we can photograph distant galaxies and stars and get pretty good pictures yet we can&#39;t get a good pic of Pluto and completely missed this new planet even though these things are a lot closer to us? This confuses me.

It isn&#39;t as simple as that; closer does not automatically mean it&#39;s easier to see. You have to take into account that stars, galaxies, etc. are much bigger then planets (millions of times bigger). Then there&#39;s the fact that stars and galxies are luminous while planets only reflect a small percentage of the light they receive from the sun (much less then 1%). Then you take into account how big the sky actually is and factor in dust, etc. then it doesn&#39;t seem that surpising.

rahuldandekar
2005-Jul-31, 06:07 PM
Well, the discovery of a new "planet" will restart the old debate of whether Pluto&#39;s a KBO or a planet...

The UT discussion:
http://www.universetoday.com/forum/index.p...topic=8327&st=0 (http://www.universetoday.com/forum/index.php?showtopic=8327&st=0)

http://news.bbc.co.uk/2/hi/science/nature/4730061.stm A news article.

So, is pluto a KBO or not??

Thorn said:

Myself, I think eventually we&#39;re going to relegate the term "planet" to an historical reference to 9 objects, and start referring to these objects with more than one classification.

Planetwatcher:

In the end we will most likely have three catagories of major planets.
1, Gas giants,
2, Rocky inner planets,
3, Large KBOs

Personally, I agree with Planetwatcher. I think there should be three categories, and that one should not use the term "Planet" lightly anymore.

Does anyone think the new object should really be called a "planet" ? It just seems to be large KBO... and there may be larger ones, undiscovered, still out there? If that possiblity is not rare, I think we should abandon calling Pluto a planet.

bossman20081
2005-Jul-31, 06:20 PM
Instead of planets, you and Planetwatcher are suggesting sub-groupings of planets? It could work, I suppose, but we&#39;ll still need a solid, numerical value to determine the difference between planet and KBO.

aeolus
2005-Jul-31, 06:32 PM
Yeah, looks like they&#39;re calling this a planet jsut becasue they&#39;ve already called pluto a planet. "Anything larger than Pluto that&#39;s further out is a planet." ??? How does that make any sense? Ipersonally don&#39;t think it does.

aeolus
2005-Jul-31, 06:58 PM
When you&#39;re at a sports stadium, it&#39;s easy to see the players on the field, cause we know who to look for and where to see them. Now try finding your friend in the seats across the stadium when you don&#39;t know what section he&#39;s sitting in, or even what he&#39;s wearing. That&#39;s the difference. Far away galaxies have distinctive patterns and shapes and wavelengths and positions we are aware of, whereas these KBOs are simply specs of light in places that we don&#39;t know where to look.

aeolus
2005-Jul-31, 07:03 PM
I see lots different with pluto and it&#39;s further-out-than-pluto counterparts. Higher eccentricities, smaller radii, rocky/icy composition, inclined orbits. Very different from the 8 planets that find themselves closer in. It loks like we&#39;re going to be naming these big KBOs "planets, but only to cover our (mistake) of naming Pluto a planet all these years. I mean, if we call Pluto a planet, I guess we have to call #10 a planet. I think we should just say, right now, that PLuto isn&#39;t really a planet, we&#39;ve been wrong the past 70 years. It will only get harder to "declassify" Pluto and friends as time goes on. If we don&#39;t we might end up with dozens of outer outer "planets", but then, if size is the limiting factor, where do you draw the limit? Pluto?

If so, then what&#39; the logic behind that?

John L
2005-Jul-31, 08:19 PM
Ok, so the Kuiper Belt supposedly cuts off at about 100AU and we now have a planet out there at 97AU. Could this world and its speculated brothers be the reason the Kuiper Belt ends there?

And what to name our 10th planet? I vote for Mellissa. She&#39;s a really cute red head that I know... or Reagan, after America&#39;s greatest President.

Nereid
2005-Jul-31, 09:22 PM
Originally posted by Greg@Jul 31 2005, 03:34 PM
Nereid, yes the source I used is from Newscientist, Jul 23-29, p. 29-32,
The principal theorist they interviewed was Eugene Chiang at the Univ of Cal-Berkley.
Thanks Greg.

I found the NS article online, but one needs to pay &#036;&#036; to view it.

I checked out Eugene Chiang and his work, but haven&#39;t found anything that he published which talks about 500-1000 au large planets (he has done a lot of work in this area, so maybe I missed a key paper).

Does the New Scientist article say anything specific, that I could google on re this?

Dave Mitsky
2005-Jul-31, 09:24 PM
Originally posted by slotdrag@Jul 31 2005, 03:36 AM
Ok if this is the tenth planet what happened to sedena? wouldnt this be the eleventh planet? Im lost whos counting? When does this become official? How does it become official?
The IAU is responsible for naming celestial objects.

http://www.iau.org/IAU/

Dave Mitsky

Dave Mitsky
2005-Jul-31, 09:28 PM
Originally posted by aeolus@Jul 31 2005, 07:03 PM
I see lots different with pluto and it&#39;s further-out-than-pluto counterparts. Higher eccentricities, smaller radii, rocky/icy composition, inclined orbits. Very different from the 8 planets that find themselves closer in. It loks like we&#39;re going to be naming these big KBOs "planets, but only to cover our (mistake) of naming Pluto a planet all these years. I mean, if we call Pluto a planet, I guess we have to call #10 a planet. I think we should just say, right now, that PLuto isn&#39;t really a planet, we&#39;ve been wrong the past 70 years. It will only get harder to "declassify" Pluto and friends as time goes on. If we don&#39;t we might end up with dozens of outer outer "planets", but then, if size is the limiting factor, where do you draw the limit? Pluto?

If so, then what&#39; the logic behind that?
I agree. IMO, it is because of sentiment and not logic that Pluto remains classified as a planet.

Dave Mitsky

Nereid
2005-Jul-31, 09:58 PM
To put numbers on all this ....

Pluto is ~5.9 billion km from us, and has a radius of ~1,000 km. This makes its disc much smaller than "seeing" (when you look through a telescope at a star, it doesn&#39;t look like a &#39;point&#39;, it looks like a swimming and dancing blob; this is &#39;seeing&#39;). The newly discovered SDOs would have a disc smaller than Plutos, because they are much further away. Although galaxies are much, much, much further away than Pluto, they are also much, much, much bigger. When you put the numbers together, you see that most galaxies are &#39;bigger&#39; than &#39;seeing&#39; (and the really distant ones imaged by the Hubble Space Telescope are much smaller; but then, Pluto can be seen - by Hubble - as a distinct disc).

Astronomers use &#39;magnitudes&#39; to describe the apparent brightness of an object, with a 5 representing a brightness ratio of 100. On a dark night, in a dark location, you will probably be able to see stars as faint as mag 6; these are 100 times fainter than all but the very brightest stars you can see (there are very few stars brighter than mag 1). Pluto is quite faint; it&#39;s ~14 mag. The new objects are much fainter, at ~19 mag. There are approx 500 million &#39;stars&#39; (point sources) in the sky of about this brightness (or brighter). The only way you could tell if one of these were a distant planet, and not a star, would be by its apparent motion across the sky. Image how challenging it is to find one or two &#39;moving&#39; objects among 500 million. Now add that there are thousands of as yet undiscovered asteroids, which also &#39;move&#39;, and most of which are also faint (almost all &#39;bright&#39; asteroids have been long since discovered).

You might know that asteroids, generally, will seem to move much faster than distant KBOs/SDOs, so a quick check should tell the difference. That&#39;s true. However, there are also hundreds, if not thousands, of as yet undiscovered KBOs and SDOs, almost all of which will likely be boringly small (we will discover them when they&#39;re at ~40-50 au from us, vs ~100 au for the newly discovered objects).

Lends a whole new meaning to &#39;needle in a haystack&#39;, doesn&#39;t it&#33; :D

Greg
2005-Jul-31, 10:25 PM
I have temporarily misplaced the magazine. It is an interview and not based on published articles as far as I recall. When I relocate it I will see if they cited any references ans post them on this thread.

slotdrag
2005-Jul-31, 10:37 PM
Ok im lost still a while back big find a tenth planet then its given a name sedena. Now its not a planet because it not bigger than pluto. Heck there moons out there bigger than pluto and othere planets. This dont make sense to me. Look how long it takes a rock to travel around the sun in orbit out that far hundreds of years. Weve only just begun to explorer and find planets in our solar system do to lack of being able to see dim items that far out. Who named these scientist gods and can judge if its a planet or not. I beleive sedena is a planet because of its orbit not its size. And i think alot of otheres do to because it was announced to the news that way a a planet.

Fraser
2005-Jul-31, 10:57 PM
I think sentiment is a perfectly good reason to keep Pluto a planet.

aeolus
2005-Jul-31, 10:58 PM
Ahhh&#33;

Moderators;
please, can we consolidate the "10th planet" topics into one? There are at least 4 on the go right now, and it&#39;s getting crazy reading the same thing over and over again. I think everyone would benefit from seeing all the questions, answers, and updates all in one place.

Thanks for your time and consideration,

Rob

TheThorn
2005-Jul-31, 11:39 PM
Yep. Pluto is a planet, for about the same reasons that Europe is a continent. Neither one makes sense in any logical definition, but history is on their side.

As I said in a post in a thread under "Other Stories", I think there are obviously two different types of objects orbiting the sun in terms of composition (I called them rocky and gassy, but that lead to confusion - low density and high density would be just as bad - the key is that one type of object is made predominantly of low boiling point materials, and the other of high boiling point materials). Easy to distinguish between the two - Mercury, Venus, Earth, Mars, and the asteroids are one group, Jupiter, Saturn, Uranus, Neptune, the KBOs, Oort Cloud objects, and comets are the other group. Very little ambiguity (I know of no object that wouldn&#39;t be eassily classifiable one way or the other).

Each of those groups comes in two sizes, major and minor, and there&#39;s a gap between the two of several orders of magnitude. Mercury is 500 times as massive as Ceres (both rocky) and Uranus is over 1000 times more massive than Ganymede (both gassy or icy). So the difference between "major" and "minor" is something found in nature, not some arbitrary limit set by man.

Nothing arbitrary about this set of definitions, and if you want to call the major ones "planets", pluto would miss out, but I won&#39;t argue with history.

Guest_lccrmt
2005-Aug-01, 12:06 AM
Thank you all for your answers--very informative and makes sense. Thanks so much for taking the time to respond&#33;

Nereid
2005-Aug-01, 12:49 AM
Originally posted by aeolus
Ahhh&#33;

Moderators;
please, can we consolidate the "10th planet" topics into one? There are at least 4 on the go right now, and it&#39;s getting crazy reading the same thing over and over again. I think everyone would benefit from seeing all the questions, answers, and updates all in one place.

Thanks for your time and consideration,

Rob
Thanks for the suggestion aeolus/Rob.

For those who are looking for their "tenth planet"/"object with orbit beyond Sedna"/"KBOs etc again"/etc thread, it&#39;s now here, all mashed together into one (thus you may find it a little disjointed to read; apologies).

[Added later: the Story Comments thread (http://www.universetoday.com/forum/index.php?showtopic=8332&hl=) on this topic is still open, but I&#39;ll close it in a day or two.]

Nereid
2005-Aug-01, 12:52 AM
There is now a single, consolidated thread (http://www.universetoday.com/forum/index.php?showtopic=8325&st=0) on the tenth planet discovery (-ies), and all related (e.g. KBOs) aspects.

Please continue discussion in that thread.

John L
2005-Aug-01, 02:00 AM
Wow&#33;&#33;&#33; So many new world&#39;s to explore&#33; I think its deep solar system probes time. I&#39;m talking "Expolration of Mars" levels of missions. We should mass produce 20 identical probes and over the following years we should launch them toward these objects as favorable gravity boost alignments occur. With the timing of Earth&#39;s and Jupiter&#39;s years we should be able to get them all launched off in a decade on high speed missions to the large KBO&#39;s. Of course, it may take 30-40 years for last missions to reach their targets, but it may be cheaper per mission to try to do them all at once. It worked for Voyager, Viking, and the Mars Rovers after all...

Planetwatcher
2005-Aug-01, 02:32 AM
I am not an astronomer so please forgive my ignorance if this question seems silly but... How is it that we can photograph distant galaxies and stars and get pretty good pictures yet we can&#39;t get a good pic of Pluto and completely missed this new planet even though these things are a lot closer to us? This confuses me.
It has more to do with how bright they are and apparent motion, then the size or distance, although both are factors.

Galaxies even though so much farther away are so much bigger, and have billons upon billions of stars generating light.
But note the extreme difficulty in photographing a single star in a distant galaxy.

Stars and galaxies also move much faster then KBOs, even dispite the much greater distancees.

On the other hand, planets, and KBOs have no light of their own. They reflect only sunlight which is much harder to detect at their distances, and is easliy overwhelmed by stars, (which from our reference point) appearing to be nearby.
They are of coarse also very much smaller then stars and galaxies, which when combined with the very slow apparent motion makes it much harder to find.

We have much the same problem with nearby stars which are smaller and cooler then the much hotter giants which are so much farther away.
For example Alpha Centauri C is the closest star to us, (outside of our Sun) and is even noticably closer then the other two stars in the Alpha Centauri system.
But it takes a healthy magnifacation to see it. In contrast the other two are much bigger and brighter, and closer together, which makes them appear as one star until you put them under signifcant magnifacation as well.

Barnards Star is the second closest star system to us, 4th closest individual star after our Sun. It is itty bitty in size. It almost takes an observtory to see it for it&#39;s small size and dimmness. But it&#39;s apparent motion is the greatest of all stars we can detect, making it possible to find with even the most primitive observatories.

In contrast, Teegardens Star. which is larger, but farther then Barnards Star eluded us until a couple years ago, because it seem to move so little.

So bigger and brigher are better, but even then sometimes you won&#39;t see it until it moves. Hope this helped.

Guest
2005-Aug-01, 02:42 AM
I wonder if Hubble can get a pic of this new &#39;planet&#39;?

Planetwatcher
2005-Aug-01, 03:49 AM
Thorn, your reply is far enough back in this thread, that I canít easily pan back and forth to quote and respond, so Iím having to do this by opening a MS Word document and doing copy and paste, so the quotes will look different then normal. (*)
Originally posted by TheThorn+--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (TheThorn)</td></tr><tr><td id='QUOTE'>
Originally posted by Planetwatcher+--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Planetwatcher)</td></tr><tr><td id='QUOTE'>Neptune is the smallest of the gas giants although not by much.[/b]Sorry, but it is not. Uranus is the least massive of the gas giants, at 8.6 * 10^25 kg. Neptune is about 20% more massive at 1.0*10^26 kg. Mass is obviously a better indicator of size than diameter in this discussion - otherwise a neutron star is a minor object compared to a planet. All through my note I was careful to repeat that I was using mass when I referred to size.[/b]
Using mass over diameter is more a personal preference, but can be deceiptive. Yes a neutron star may have 1 solar mass and be smaller then a moon. But also the planet Saturn is so light, that it would float on water. Itís mass is 5.68e26 kg. making it lighter by mass then any other gas giant.
I sort of like to use diameter myself.
Originally posted by TheThorn

Originally posted by Planetwatcher
Ceres is more like 480 times smaller then Mercury.This is true. You appear to have used mass here, rather than diameter. Good. The point remains, there is a HUGE, unmistakable difference between major and minor.
No, I used diameter again, but I roughly estimated as it was getting quite late for me by then. and the ole brain begins to lolly gag..
Originally posted by TheThorn

Originally posted by Planetwatcher

Originally posted by TheThorn
and the largest minor gassy object (Ganymede) is over 1,000 times smaller in mass than the smallest major gassy object (Uranus).I never heard of minor gassy objects, and certainly not Ganymede as anything like that. In fact Ganymede doesn&#39;t even have an atmosphere, although it is the largest of all moons, even larger then Titan, which does have an atmosphere.The term gassy object was my own. I said:
I think, if you look at the question of composition, you have two types of objects, gassy (or icy if they&#39;re cold) and rocky. This probably depends on where they formed.
I didnít miss it. Ganymede has no ice. Could you have been thinking of Europa?

There may be ice on moons orbiting gas giants, or there may be an atmosphere. This does not make it a gassy object by any standard. Gas means gas. Not a gasuis element turned to ice because itís cold.
The gas giant planets are so because they generate their own heat and radiation. Enough to keep gas in itís proper form. Letís not invernt new standards here.<!--QuoteBegin-TheThorn@
<!--QuoteBegin-Planetwatcher
This is perhaps the bigest error of all.There is no gas associated with KBOs other then we know that Pluto has an atmosphere, and are pretty sure that Charon, and Sedna have atmospheres as well. Although they are frozen atmospheres.[/quote]
I DID say icy as an equivalent. It really was there, if you would have read a little more carefully. (Sorry if I&#39;m getting defensive).[/quote]
Again, gassy objects are very different then icy objects and in more ways then where they were formed..
You also referenced comets saying they are only KBOs perturbed from their orbit.
Which can be true, but also untrue. Some comets come from outside the Kupier belt, out in the Orrt Cloud. Some comets never make it as far as the Kupier belt, nor ever approach the Sun. For example,
2060 Chiron has been recently reclassified as a comet, but always stays between Saturn and Uranuses orbits, never approaching either the Sun, or Kupier region. It is also not known to have any ice either.
This term gassy is not a good descriptin other then for giant planets, and stars. It wouldnít even be accurate to call a nebula gassy even though thatís what it is.

Your taxonomy seems somewhat arbitrary to me. What&#39;s the difference between "Large KBOs" and "Small KBO&#39;s
Far be it from me to call a standard, but based on what I understand in reading works of professional astronmers, and even well educated amaturs, there appears some well known prima facia standard at which large or small, major or minor are determined.
KBOs smaller then 1000 Km. in diameter are not refered to as large except for 2002 AW197, and Varuna, which are included only because the plus/minus range puts them possibley above 1000 Km.

Pluto was desinated a planet long before other KBOs were discovered. I suspect had the KBOs been known all along then Pluto would have never been included as a planet. But it was and now must be dealt with in one of two manners.
1, Call any KBO around Pluto size or larger a planet, (unless it is a moon of another object)
or
2, Remove Pluto from planetary status and simply call them all KBOs.

My say has no bearing on decissions of professional astronomers, but based on my working knowledge of astronomers and astronomy, I believe number 1 is what will happen.

Now I happen to support that idea as well because it makes since to me, but it is only coincidence.

[*Edit by Nereid: fixed all the QUOTE tags (I hope)&#33;]

TheThorn
2005-Aug-01, 05:04 AM
But also the planet Saturn is so light, that it would float on water. Itís mass is 5.68e26 kg. making it lighter by mass then any other gas giant.

Uranus, 8.7e25 kg. Neptune, 1.0e26 kg. Saturn, 5.68e26kg. Saturn is certainly NOT "lighter by mass than any other gas giant." See
Planetary Fact Sheet (http://nssdc.gsfc.nasa.gov/planetary/planetfact.html)





Ceres is more like 480 times smaller then Mercury.


This is true. You appear to have used mass here, rather than diameter. Good. The point remains, there is a HUGE, unmistakable difference between major and minor.

No, I used diameter again, but I roughly estimated as it was getting quite late for me by then. and the ole brain begins to lolly gag.

LOL. Quite a coincidence, then. Your 480 number is close in terms of mass, but way off in terms of diameter. Ceres, diameter, 960 x 932km. Mercury, diameter, 2540 km. So in diameter, Mercury is about 2.5 times as big as Ceres.

Ceres, mass 8.7e20 kg. Mercury, mass 3.2e23 kg. So in mass, Mercury is 368 times bigger than Ceres.

Again, the point is that there is a huge gap here, so it is easy to distinguish between major and minor. Not like the arbitrary 1000km you (and others) suggest. There are guaranteed to be objects 999 km in diameter and others 1001 km. If there was something rocky in the solar system between Mercury and Ceres in size, we&#39;d know about it. (and actually it exists and is the moon, but I&#39;ve alreadys admitted it&#39;s a problem for my idea.)


I didnít miss it. Ganymede has no ice. Could you have been thinking of Europa?

I could very well be wrong saying that the composition of Ganymede is primarily icy, but you are certainly wrong when you say it has no ice. See here. (http://www.nineplanets.org/ganymede.html) It has a three layer structure; a small iron core, a rocky mantle and an icy crust. Given its density is under 2, it is probably more ice than rock and iron, but it&#39;s a close call. Io and Europa are bigger problems, but I think it&#39;s safe to say that over billions of years, they have been modified by Jupiter - their volitiles have probably been stripped away to some extent.


Gas means gas. Not a gasuis element turned to ice because itís cold.

Pick your term, PW. I&#39;ve tried to make myself clear, and you appear to want to play semantics. What word would you like me to use for objects composed as I described elsewhere, primarily of materials that would be gasses at room temperature (please allow me to throw in water, the only common material that is a liquid at room temperature)? Gassy? Icy? Low density? All could be misleading, but I&#39;m just looking for a label.


You also referenced comets saying they are only KBOs perturbed from their orbit.
Which can be true, but also untrue. Some comets come from outside the Kupier belt, out in the Orrt Cloud. Some comets never make it as far as the Kupier belt, nor ever approach the Sun. For example,
2060 Chiron has been recently reclassified as a comet, but always stays between Saturn and Uranuses orbits, never approaching either the Sun, or Kupier region. It is also not known to have any ice either.

According to the most accepted theories of solar system formation, the Oort cloud is made up of objects that used to be KBOs - or rather, the KBOs are the left overs of a much larger belt that included the area currently inhabited by the gas giants, but the gas giants perturbed most of those objects either into the inner solar system or out into the Oort Cloud. So comets from the Oort Cloud are really KBO&#39;s making a return.

Chiron is a great example of my point. It was classified as a Centaur, but it&#39;ss now classified as a comet, because it showed a period of cometary activity (i.e. it gave off gasses). It is composed of volatile material, similar to the KBOs and (for that matter) the gas giants. It isn&#39;t big enough to generate enough internal heat, so those materials exist in the form of ices. If it weren&#39;t for that period of cometary activity, it would be indistinguishable from any other KBO. And you should note that its current orbit is not stable. It did not form there, but was perturbed into that orbit (almost certainly from the Kuiper belt), and it will not stay there forever. Eventually (perhaps millions of years, but short in terms of the lifetime of the solar system) it will either be flung out into the Oort Cloud (or right out of the solar system altogether), or inward, to become one spectacular comet.

So what is it? The KBO that it was? The Centaur that we classified it as for a couple of decades? Or a comet? Or the Oort Cloud object that it might eventually become? It&#39;s just one thing, not 5. Changing the circumstances of its orbit doesn&#39;t change the type of object it is.


there appears some well known prima facia standard at which large or small, major or minor are determined.
KBOs smaller then 1000 Km. in diameter are not refered to as large except for 2002 AW197, and Varuna, which are included only because the plus/minus range puts them possibley above 1000 Km.

That&#39;s a great example why I think 1000 km is arbitrary. If there were an icy or gassy or whatever-word-you-want-me-to-use object in the solar system between Uranus and Ganymede in mass, we&#39;d know about it. There&#39;s a huge gap in the spectrum of object sizes there. So why would we want to put are demarcation line at 1000 km, right in the middle of a range of sizes that we know is a continuous spectrum? Same thing for the rocky ones, as I pointed out above.

The only reason that it is hard to see the gap is that historically we&#39;ve lumped the two types of objects together, and Ganymede (the biggest minor whatever-you-want-me-to-call-them) is almost as massive as Mercury (the smallest major rocky object). But when you view the two types of objects separately, the distinction between "big" and "little" in each group is very very clear.

That was my whole point. Sorry that I&#39;m so poor at explaining myself.


Pluto was desinated a planet long before other KBOs were discovered. I suspect had the KBOs been known all along then Pluto would have never been included as a planet. But it was and now must be dealt with in one of two manners.
1, Call any KBO around Pluto size or larger a planet, (unless it is a moon of another object)
or
2, Remove Pluto from planetary status and simply call them all KBOs.

My say has no bearing on decissions of professional astronomers, but based on my working knowledge of astronomers and astronomy, I believe number 1 is what will happen.

Now I happen to support that idea as well because it makes since to me, but it is only coincidence.


You may very well be right, but I suspect that Pluto will remain a Planet, for historical reasons (like I mentioned above, Europe is a continent for the same reasons).

The reason I think a scheme like mine would make more sense, is that it uses nature&#39;s own dividing lines to demark the types of objects. I believe that a good nomenclature helps us to understand phenomena. The binomial nomenclature of Linnaeus made understanding the relationships of species (and ultimately the understanding of evolution) easier. It was based on divisions between types of organisms that are clear in nature, not some arbitrary dividing line. (Yeah, everything in the ocean bigger than 1000kg we&#39;ll call a whale, everything smaller, we&#39;ll call a fish. That ought to cover it.)

I hope when the dust settles, they&#39;ll have a sound basis for classifying objects in space - one that will help us learn, not get in the way.

rocketblair
2005-Aug-01, 05:27 AM
I think changing Pluto to the closest KBO makes much better sense. Pluto has a lot more in common with the other rock/ice bodies in the KB than it does with the inner planets or gas giants. The Pluto lovers need to realize that yes, history can&#39;t be changed, but reclassifying It as the closest KBO to earth would enhance it&#39;s place in history. It&#39;s quite understandable why it was called a planet at discovery, but If Pluto remains a "planet" then there will be more and more planets added. I think all the bodies beyond Neptune regardless of their size should be KBO&#39;s or OCO&#39;s if found in the Ort Cloud. Of course, many af these objects are comets, I&#39;m just talking about the larger bodies being discovered recently. Some astronomers believe we will find earth sized objects nearer to or in the ort cloud. We are just beginning to get a grip on the outer solar system, so we need to use a reasonably simple classification system until we have more info about how ours and other solar systems form and evolve.

Planetwatcher
2005-Aug-01, 06:56 AM
At last report Pluto was enjoying duel citizenship as both planet and KBO, although I don&#39;t know if it is the closest one or not.

However if a third catagories of planets is brought about, they will all be KBOs because, Pluto, Quaoar, Varuim, Ixen, and at least two of the three new discoveries are all KBOs. They all behave the same way, orbit in simular fashion, are of simular makeup, and the same general neighborhood of sizes. Between a thousand and twenty five hundred Km. in diameter.

Sedna, and 2003 UB313 are under a lot of speculation about if they are actually in the Kupier Belt, or Orrt Cloud.
It&#39;s entirely possible they will be regarded and join Pluto as planets 10 and 11, or they may be left out simply because of distance, in which case 2003 EL61, and
2005 FY9, may be designated planets 10 and 11.

Equally possible is that Sedna gets left out because it is substantually smaller then
the others, and all three 2003 EL61, 2005 FY9, and 2003 UB313 are declared planets 10, 11, and 12.

Also possible is that Sedna, Quaoar, Ixion, Varuna, 2004 DW, 2003 EL61, 2005 FY9, and 2003 UB313 are redesignated planets 10 through 17. :P

But then maybe nothing will happen, or maybe asteroid fans will push for Ceres, as long as planets are being renumbered, making it number 5 instead of Jupiter, and bring a renumber out to 18.

Then maybe pigs will fly and cows will come home too. :lol:

Planetwatcher
2005-Aug-01, 07:03 AM
I thought we were consolidated, but it didn&#39;t seem to work so well.

Calling all mods, let&#39;s go upstairs and get this figured out.

Greg
2005-Aug-01, 07:13 AM
I believe in keeping things as simple as possible, but we need a few more characteristics to define what is called a planet. Clearly Pluto is a KBO and should be classified along with similar objects. The key criteria to use that would seperate them out would be mass, diameter, orbital eccentricity, whether it orbits a larger object, and distance from the sun. Composition may also be useful. This system then be sanely applied to other solar systems as we discover them so we will know what we are talking about when describing those objects also. The time to do this is ever so clearly now. Planets should be designated terrestrial or gas giant. An example would be pluto. It has none of the characteristics of the 8 major planets and its composition is entirely different as well. The only argument I would entertain is whether to name all of the KBOs planets as well and just designate them Planet-KBO as opposed to P-terrestrial or P-gas giant.

cran
2005-Aug-01, 07:50 AM
wow&#33; I thought the heated debate was only going on between the discoverers and the IAU...

I&#39;ve come across the term &#39;planetoid&#39; for any object which has its own definable orbit around a star, is massive enough to form into a sphere, and which (for whatever reason) doesn&#39;t rate the label &#39;planet&#39;.

There is a danger to applying definitions of planets based upon diameter (with the potential for some KBOs to be larger than the smallest planets), mass (highlighted recently by the find of the &#39;super-superjupiter&#39;; is it a planet, or a failed star?), or density (Saturn was a good example); if the extra-solar planets are any guide, then eccentricity and inclination will not be factors.

Then, of course, there are the postulated objects of planetary mass which are wanderers (not gravitationally bound to any star), and which some have called &#39;rogue planets&#39;.

Hey&#33; If the biologists are allowed to proclaim whole new kingdoms of life (and just look at what that has done to the old textbooks and wall-charts), why can&#39;t astronomers proclaim some new classes of astonomical objects?

Or, simply proclaim that the number of planets in our solar system is 18 at last count, and subject to change at any time - as has been the case for natural satellites - remember when Jupiter had 12, Saturn had 9, Uranus had 5, and Neptune had 2?

rahuldandekar
2005-Aug-01, 08:10 AM
I guess everyone will now agree that pluto is a KBO.

Maybe if diameter, mass and density fail, we can rely on composition (and common sense, what else&#33;). I guess if Pluto is a KBO, it&#39;s composition will be different from the Major planets. Gas giants and terrestrial planets can be differentiated on the basis of composition. Astereroids can be differentiated on the basis of Composition, and Common sense ;) .

Maybe we can group KBOs into two groups, "large", and "small": "large" being those who we would have traditionally given "planet" status (eg. Pluto and "10", because they are round).

P.S. This will really wreak havoc with our astrologers. Hehe.

piersdad
2005-Aug-01, 08:14 AM
O M G
we have forgotten all the astrologers
they must be very busy trying to wriggle out of this one
perhaps they will sue the discoverers for upsetting them

aeolus
2005-Aug-01, 11:24 AM
Originally posted by John L@Aug 1 2005, 02:00 AM
Wow&#33;&#33;&#33; So many new world&#39;s to explore&#33; I think its deep solar system probes time. I&#39;m talking "Expolration of Mars" levels of missions. We should mass produce 20 identical probes and over the following years we should launch them toward these objects as favorable gravity boost alignments occur. With the timing of Earth&#39;s and Jupiter&#39;s years we should be able to get them all launched off in a decade on high speed missions to the large KBO&#39;s. Of course, it may take 30-40 years for last missions to reach their targets, but it may be cheaper per mission to try to do them all at once. It worked for Voyager, Viking, and the Mars Rovers after all...
Formidible idea, a great gift we can give to our children. I think a few significant advances in nanotechnology would do a great deal to turn your idea from "possible" into "probable" and "pressing".

rahul, piers;
laughing out loud&#33; does anyone know what happened to that crazy lady&#39;s lawsuit? Did anyone watch the letters & words change in their horoscope on July 4th?

rahuldandekar
2005-Aug-01, 11:44 AM
Newspapers are silly - one newspaper here actually asked astrologers what "effects" this 10th planet will have. Some of them said "no effect" (no, not because it was far off) because "we take into consideration only planets upto Saturn."

But the most famous astrologer here dished out some worthless crap:
(Not quoting accurately) " I have been waiting for this, it was time for the tenth planet to be discovered. The new planet stands for the new age. " (Poor guy, the number of planets may now be 8, or even 18&#33; And talk about hindsight&#33;) "The number 10 includes 1 and 0, which stand for the sun and infity respectively. " Huh? if the sun is 1, shouldn&#39;t "10" be "11"? And 0 is infinity? Talk about paradoxes&#33;

Maybe I should browse some astrology forums, and find out some more crap.

Beholder
2005-Aug-01, 12:06 PM
I don&#39;t understand all this discussion.

Pluto is classified by IAU as BOTH a planet and a asteroid (since it was given an asteroid number).
So, by definition, ANYTHING which is not a star, brown dwarf or black hole, orbits a star, and consists of normal, baryonic matter :D AND is larger than Pluto, IS a planet.
Also, anything smaller is NOT a planet.

In Herschel&#39;s time, nobody had a problem with increasing the number of planets from 6 to 7.
In Leverrier&#39;s time, nobody had a problem with increasing the number of planets from 7 to 8.
So, what tells you all that the total number of planets must stay at 9 (or 8, respectively)? Are these HOLY numbers?

Educated guesses, judged by the numbers and sizes of KBOs already discovered, show, that there will probably be about 3-4, now 2-3 bodies bigger than Pluto out there. So would it be such a problem, if the solar system had 13 or 14 planets?

since the compositions of small planets and asteroids are similar anyway, the lower limit of "planetability" must be arbitrarily anyway. So why not use Pluto as a lower limit? For every other limit there is even less reason, since the historical reason would be dropped too. ;)

@ Greg:
would you classify Mercury as an asteroid, just because it&#39;s smaller than Ganymed?

rahuldandekar
2005-Aug-01, 12:21 PM
Ceres is no different than the other asteroids, it is just bigger, and is classified as an asteroid. Similarly, Pluto, Sedna, and new Planet, and the other 2-3 undiscovered planets are not different than the other KBOs, just larger. The four Gas giants and the four terrestrial planets are different from the KBOs in Orbit eccentricities, compositon, etc.

So, Pluto and number 10, which are the same as KBOs, fall into a category to which they do not belong, just because they are larger. The category where they do belong is KBOs. That&#39;s the problem with the "Pluto as least size" limit. It does not take into account other classifying factors.

antoniseb
2005-Aug-01, 12:23 PM
Originally posted by Beholder@Aug 1 2005, 12:06 PM
ANYTHING which is not a star, brown dwarf or black hole, orbits a star, and consists of normal, baryonic matter AND is larger than Pluto, IS a planet, anything smaller is NOT a planet.
I am curious why it matters so much to so many people what objects are called planets and what objects are not. Calling an object a planet vs. a larger asteroid or moon does not increase the property value of the acreage on its surface, or change the value of its mineral resources.

Planet is a term for laymen that does not yet have a precise meaning, and possibly never will. The meaning that I quoted above is as good as any, even if it was written intending to show how arbitrary the current working definition is.

rahuldandekar
2005-Aug-01, 12:40 PM
Thanks for that clarifying post, Anton.

Actually, it&#39;s just a matter of useful classification and logical consistency.

If pluto is called a planet, and so is number 10, lay people will be (mis)led into believing that these differ from the other KBOs like Sedna, and are similar to the other 8 planets. We&#39;ll have to clarify that they are planets, but are similar to KBOs, and not to the other planets. Instead of that, we can classify the bodies as Gas Giants, Terrestrial planets and KBOs, leading to a useful classifying system.

If number 10 and Pluto are still planets, then Solar system diagrams will show the 10 planets, and nothing in between, or just a KBO belt. That&#39;s not correct, because 9 and 10 are just like KBOs, only bigger.

lambda_guy
2005-Aug-01, 01:11 PM
Hi @ll,

For years, Pluto has been classified as a planet and it has not been a problem for anybody.

Now that we&#39;re discovering more and more Plutos-like celestial objects,
it seems that we can&#39;t accept them as planets.

Is it for their geometry, mass or composition ?
of course not : If Pluto is a planet based on these criteria, Sedna and new planetoÔds would have been too. and without any controversial debates

Is it for their orbits or their localization ?
neither

In fact, the actual criterion, somewhere hidden in our mind, is the unicity of the planets or more honestly the unicity of earth-like objects.
something close to the supposed unicity of the humankind &#33;&#33;&#33;
Remember : For billions humans in our world, we are uniques.
We are not animals&#33;
But what&#39;s the difference between humans and apes? Maybe the same as planets and planetoÔds ...
Is it a problem? Not for the moment. so let&#39;s go on with that

Of course, I&#39;m wrong, but if I were right, what to do?
- classify new objects as planets? No. There is no need to break our &#39;unicity myth&#39; now
- declassify Pluto ? If possible yes&#33;
But for that we need a new and stable definition for planets.
A definition from objective criterions, &#39;calculated&#39; from the &#39;unicity myth&#39;

But we can&#39;t find that perfect definition for planets, which will be robust to new planetoids findings and that won&#39;t break the hidden unicity myth...

That&#39;s why I think it&#39;s better not to change anything yet.
In any case, it won&#39;t be accepted yet by most of us ...

That&#39;s also the reason why lot of unregistered people like me will react in this topic.

but I&#39;m surely wrong ...

rahuldandekar
2005-Aug-01, 02:30 PM
There is no unicity myth.

Pluto is not a planet based based on these criteria, it is probably a planet because the discoverers were excited about discovering a new planet-like object beyong unranus, and however small, they wanted to call it a planet. But the new discovery shows how faulty the conclusion was.

As Thorn said before, the word "planet" will now become a mere historical term. Yes, we can find the perfect definition for a planet. Maybe it will only refer to the 9 planets from now on. We can form robust definitions for gas giants, terrestrial planets and Kuiper Belt Objects.

Those definitions should go into practice now, because we start naming every pluto-sized body discovered in the Kuiper Belt as a planet. But we can classify it as a KBO.

John L
2005-Aug-01, 03:56 PM
In my opinion we need one unified definition of what a planet is.

A planet should be designated as any body that&#39;s orbit is basically centered on a star, has been made spherical due to the force of gravity, that has a differentiated interior, and that does not share its orbit with similarly sized bodies. A possible modification could be added about fusing hydrogen or its isotopes in the core disqualifying planethood and pushing the body into a sub-stellar or stellar classification system (brown dwarfs, red dwarfs, stars, white dwarfs, neutron stars, and black holes).

Mercury is a planet, as is Venus, Earth, and Mars. The various moons of the solar system have their orbits centered on a planet rather than a star so they are not counted as planets. The largest asteroids like Ceres and Vesta are spherical and differentiated, but they also share their orbits with thousands of other bodies of similar size so they are all what we&#39;ll call asteroids. Jupiter is a planet although it shares its orbit with what we call the trojan asteroids. As there is no similiarity in size between the massive gas giant Jupiter and the tiny trojans there is no question about Jupiter&#39;s planethood. Also, Saturn, Uranus, and Neptune are planets. Pluto shares its orbit with a large number of similarly sized bodies. Like the asteroids between Mars and Jupiter there are distinct groups, or belts, of these bodies, but the ratio of smallest to largest, with multiple bodies in each size range makes these bodies all part of a general belt. The largest members, like Ceres and Vesta, are merely members of the belt and should not be considered planets. This demotes Pluto.

In the mid 1800&#39;s there were LOTS of new planets. Ceres, Vesta, Pallas, Juno, and the other largest members of the asteroid belt that were first discovered then were named as planets. At one point Jupiter was the 11th planet in our solar system&#33; But astronomers realized that as these bodies all shared the same orbit they should be given a new designation - asteroids. If we REALLY want to keep the designations historical, then demoting planets like Pluto down to a lesser status like KBO because they were discovered to share their orbits with lots of similar objects is the historic method. It is only because it took our telescope technology 75 years to catch up that we didn&#39;t discover the rest of the KBO&#39;s more quickly and realize that Pluto as a planet was the wrong designation. After all, we&#39;re not looking between Jupiter and Mars but out to the very edge of the known solar system. All of the large asteroids were found first, but the time span between their discovery and the realization that there was a whole belt of objects in that orbital area was only a few years. Had it been 75 years between the discoveries of the largest six asteroids and the rest of the belt would we still want to call Jupiter the 11th planet, or would we demote them and bump Jupiter back down to #5?

burmese
2005-Aug-01, 05:04 PM
Well, looks like Brown and Co. get the top billing:

http://news.independent.co.uk/world/scienc...ticle302931.ece (http://news.independent.co.uk/world/science_technology/article302931.ece)

2003 UB313 will apparently be catalogued as a planet and be called &#39;Xena&#39;

*****
...
The astronomers have submitted their name for it - from the warrior princess in the 1990s TV series - to the International Astronomical Union and are confident it will be designated a planet, although the procedure for approval is somewhat hazy because no new bodies have received that designation since Pluto was found 75 years ago, Professor Brown said. "We hope it&#39;s fairly non-controversial among those who believe Pluto is a planet," he said. "I would say, &#39;Get out your pens and start rewriting the textbooks today&#39;."
...
*****

LIFEONPLUTO
2005-Aug-01, 05:57 PM
They didn&#39;t name it a planet just because it was bigger than pluto, because if they did we would have thousands of planets right now, it&#39;s more deep than that.

John L
2005-Aug-01, 05:58 PM
Very funny about the name&#33; I clicked the link and nothing came up and for a second I was freaking out that they really were going to call it Xena&#33; :P

I say call it Rupert after the 10th planet from the Hitchhikers Guide to the Galaxy... or Timmy after the kid in the wheelchair from South Park.

John L
2005-Aug-01, 06:50 PM
According to this Nature article (http://www.nature.com/news/2005/050801/full/050801-2.html) the International Astronomical Union will now issue their official definition of a Planet by the end of this week rather than next summer&#33; No one outside the IAU knows what they&#39;ve decided yet, but it will have implications on the official teachings of the structure of the solar system. If they use my definition above then Pluto will no longer be a planet. If they do not include the shared orbit clause then we could possibly have a lot of planets suddenly spring up in our solar system. Imagine getting four or more new planets between Mars and Jupiter and a dozen little ones past Neptune&#33;

g-bomb
2005-Aug-01, 07:06 PM
damn.. if pluto is not a planet anymore i wonder if the story book i wrote about pluto and the plutonian who lives there in his ice cave will be worth a ton of money.. i wrote that back when i was like 8 years old.. it is an awsome story.. maybe ill scan the pitures and put it up..

anyways.. ive allways liked pluto.. its all hangin out back there in the back, cold, barren, lifeless.. its an outsider..

i think pluto will probably stay a planet.. but just so we dont hurt its feelings.. behind its back we will all talk about how its really a KBO along with the thousands of otheres like it.. long live PLUTO..

<p.s> if we decide to name any new planets.. like the objects that are most similar to pluto and have orbits on the main plane.. we should name them after disney characters .. like goofy, donald, mickey, daffey.. that would be fitting i think

suitti
2005-Aug-01, 07:42 PM
Originally posted by Guest@Aug 1 2005, 02:42 AM
I wonder if Hubble can get a pic of this new &#39;planet&#39;?
HST images of Pluto are something like 11 pixels across. 2003UB313 is
a little bigger but more than twice as far away. I&#39;d expect something like
three pixels across, maybe 7 pixels total. Still, such an image might show
a moon, which would be cool, as then the masses of the two objects
could be determined.

suitti
2005-Aug-01, 08:44 PM
Naturally, with three sort of similar objects announced in a couple days, there is bound to be some confusion. On top of that, there seems to be no end of confusion as to what is a planet, and who gets to say if an object is one or not.

The three new objects are 2003UB313, 2003EL61, and 2005FY9. There. Is that all clear?

2003UB313 is currently 97 AU from the Sun in a 36 AU by 97 AU orbit. It&#39;s diameter is thought to be in the range from 2300 km to 3200 km. Larger than Pluto. Look for it in half of it&#39;s year - 280 Earth years at only 36 AU. It should be at least 4 times as bright - perhaps 16th magnitude. I can hardly wait&#33;

2003EL61 is currently 51 AU from the Sun. It&#39;s about 1600 km in diamter - 70% the diameter of Pluto. It&#39;s mass is 32% the mass of Pluto. It&#39;s mass is known because it has a little moon in a 49 day orbit.

2005FY9 was also announced. It&#39;s smaller, but I haven&#39;t seen much on it. Presumably, an orbit has been determined, at least.

The newly discovered objects are not planets, at least not yet, according to the IAU - the International Astronomical Union. We could each decide what is and isn&#39;t a planet, but the resulting confusion of terminology would be bad - perhaps the end of life as we know it. The IAU hasn&#39;t had a chance to admit more objects into the planet club as yet, at least in our solar system.

What will the IAU say? Well, for one thing, there is no IAU approved definition for the term planet at the moment. IMO, this is bad. For one thing, it means you can&#39;t predict how the politics will play out. So, all you can do is prepare several new versions of your basic astronomy textbook, and release the correct one when the IAU gets around to voting. If you want to preprint them, expect to send many of them to the recycling bin.

For the ancients, a planet was a wandering star. This definition worked pretty well. You look up into the sky, and if it looked like a dot, and it moved around, then it was a planet. Today, that definition implies that planets are naked eye point objects that move. By this definition, Mercury, Venus, Mars, Jupiter and Saturn are planets. If the ancients had noticed Uranus, it would be one too. Of note is that Pluto, Neptune, and the Earth are not. The ancients also considered the Sun and the Moon as of the seven heavenly objects. Again, Dirt... I mean Earth wasn&#39;t one of them.

With the advent of the telescope, and some hard work, people get the idea that planets are spherical things that orbit the Sun. The proposed definition that I like preserves this, but adds some constraints. One does not want every grain of sand that happens to orbit the Sun be called a planet. One convenient low end size constraint is the size a body must be before it collapses to at least more or less a sphere under it&#39;s own gravity. That happens at around a diameter of 700 km (434 miles). At the large end, if an object were big enough, it would undergo fusion, and therefore would be a star. That happens (with Deuterium?) at about 13 times the mass of Jupiter. So, an object that orbits the Sun, but not also another body, that is at least 700 km, but less than 13 Jupiter masses is a planet. The shortened version is "a spherical non-fusor in orbit around a fusor". Under this definition, the current nine planets remain planets. Ceres, Varuan, Quaoar, Sedna, and at least two of the new ones, 2003UB313 and 2003EL61, and probably a couple others are planets. Vesta isn&#39;t, as it is only 525 km, for example, even though it&#39;s pretty spherical.

Other people say that Pluto shouldn&#39;t be a planet, but rather a Kuiper Belt object. IMO, fooey. Jupiter, Saturn, Uranus and Neptune are gas giants, but they are planets too. Mercury, Venus, Earth and Mars are terrestial planets (rocky), but they are planets too. There isn&#39;t any reaon that Pluto can&#39;t be studied as a Kuiper Belt Object (KBO) along with other KBOs even if it keeps it&#39;s membership in the planetary club. IMO, the concept and definition for planethood is a public sort of thing, and ought to have the simplicity that the public can cope with. IMO, it&#39;s a good thing that the public has some sort of clue that planets are like the Earth, only "out there", rather than that they are "points of light that move".

As for Planet X, planets don&#39;t really have numbers. Pluto was closer to the Sun than Neptune from 1979 to 1999. During that time, it was the 8th planet. If my favorite definition is approved by the IAU, Ceres becomes the 5th planet from the Sun, and Pluto becomes Planet X, the 10th planet from the Sun. However, as it is currently 39 AU out, and 2003UB313 will be only 36 AU out in 280 years, so the numbering could continue to change.

If you disagree, well, YOU&#39;RE WRONG... I mean, sure, I&#39;d like to hear your opinion.

Planetwatcher
2005-Aug-01, 09:04 PM
2003EL61 is currently 51 AU from the Sun. It&#39;s about 1600 km in diamter - 70% the diameter of Pluto. It&#39;s mass is 32% the mass of Pluto. It&#39;s mass is known because it has a little moon in a 49 day orbit.

2005FY9 was also announced. It&#39;s smaller, but I haven&#39;t seen much on it. Presumably, an orbit has been determined, at least.
Now where is this data coming from?
It seems to stand in contrast to we received on Friday.

2005FY9 is also supposed to be bigger then Pluto, and 2003EL61 was reported to be as big, perhaps bigger. Now youre telling us it is barely bigger then Sedna.

Please tell us your source.

TheThorn
2005-Aug-01, 09:26 PM
Just a point about Pluto. When it was discovered, no one had much of a clue as to how big it was. When I was a kid, estimates of its size were hazy, but all had it much larger than it really is, usually in the Mercury or Mars range. Estimates of its size have been constantly going down since it was discovered.

So, thinking that it was a lot bigger than it really is, no one can blame them for calling it a planet at the time. Is it not possible to re-evaluate that sort of decision?

Also, if 2003 UB313 had been discovered in 1991, it would almost certainly have been labeled a planet. It&#39;s bigger than Pluto, farther out than Pluto, and in 1991, no KBOs had yet been found, so it would have been unique. Then as all those other KBOs were discovered (over a thousand of them by now), we&#39;d have to have re-evaluated 2 planets (just like they did with the asteroids). Timing is everything.

When they discovered Sedna, Brown et al said that it was not a planet, and that in their opinion neither was Pluto. There was an public reaction when the question of Pluto&#39;s planethood was raised, and they accepted that. Based on that, this time they&#39;re saying, basically, "If Pluto&#39;s a planet, so&#39;s this thing." And under their breath, they&#39;re adding "and there&#39;s a lot more where that came from".

John L
2005-Aug-01, 10:53 PM
OH, I agree that they&#39;re more than willing to milk this for the publicity and the future research grants if they can get them. To be the first team to discover a planet in our own solar system since the 1930&#39;s is a huge thing, but, like you said, they know the truth. A KBO is a KBO is a KBO regardless of how big it gets. Of course, if they found a Uranus sized ice giant out at 150 AU then that would be something, or a brown dwarf out at 500AU, but this and all the rest - including Pluto - is just another KBO. And I&#39;d still call it Rupert&#33; :P

John L
2005-Aug-01, 10:55 PM
What are the astrologers going to do if they make Rupert a planet? Are we going to find out what happens when Rupert is rising in Leo? Will Virgos suddenly become distant and sullen rather than compasionate? How will Rupert in opposition to Saturn effect your choice of careers? And why the heck didn&#39;t the astrologers know about Rupert in the first place??? :P

julesy
2005-Aug-02, 01:45 AM
Totally agree, Pluto is not a planet, and if the IAU decides to keep it as a planet they&#39;re allowing for a helluva a lot of confusion in the future as more and more KBOs are discovered. Why the heck they can&#39;t just demote Pluto back to KBO status and not refer to it as a planet is a complete mystery to me. Are people really that sentimentally attached to an object on the edge of the Solar System like Pluto that no one has ever even seen up close?

It really baffles me about why it&#39;s so hard to change, just what are the vested interests in Pluto, i really don&#39;t understand?

Greg
2005-Aug-02, 01:53 AM
Here is a link to an article regarding the above statistics.

http://www.msnbc.msn.com/id/8756128/

Greg
2005-Aug-02, 02:13 AM
I looked back at the newscientist article and bedises Chiang, they also interviewed Scott Kenyon of Harvard Smithsonian Center for Astrophysics who describes computer simulations he has done and articles either published or pending publication.
To summarize their position, they have simulated an accretional model of planet formation for our solar system. The term Oligarchic planet formation describes this theory and it has caught on in some circles. In this scenario all oligarchs begin more or less on the same footing growing in size at roughly the same rate. There would be 20-30 in the inner solar system and an equal number in the outer solar system. Gas giants form not from gravatational instability but as a result of fortuitous location around a gas rich area in the disc. These then grow faster and larger than the others, eventually flinging most into ecentric orbits as they migrate in and out from the sun. Jupiter would be able to throw them the furthest, perhaps as far as 1000-10000 AU. The KBO&#39;s eccentric orbits would be the work of interacting with Neptune as it pushed further out from the sun.
This is a good article, worth reading a few times, as it presents the opposing viewpoints as well as to how gas giants form, including a snippet from Alan Boss of the Carnegie Institution in Washington, D.C.
The proof of this theory revolves around an interesting find asteroid 2001 QR 322, found by Chaing, which is essentially a Trojan asteroid of Neptune. Chiang predicts that several more of these will be found and they strongly support his model. More powerful all sky surveys like the Discovery Channel telescope (5.4m) and the LSST (Large Synpotic Survey Telescope 8.4M) will be able to answer the question definitively as they will be able to see out to 500-1000 AU.

rahuldandekar
2005-Aug-02, 03:45 AM
It ain&#39;t a planet. Neither Pluto, nor Number 10 are planets. They are simply KBOs. As for me, I agree with Thorn&#39;s posts which was made a few pages ago, that "Planet" will now become a historical term only".

Maybe we should define Gas giants, Terrestrial planets, and lump these two into the category "Planet". Pluto and Sedna and Numbar 10 should be KBOs, and Ceres and the others should be asteroids.

But this is what we&#39;ve been saying for the last four pages. I say, let&#39;s wait for the IAU&#39;s definition of a planet. Can they make a definition which includes Pluto and number 10 but excludes Sedna and other KBOs. I guess they&#39;re counting on size.

julesy
2005-Aug-02, 04:35 AM
Yeah, we should wait for the decision of the IAU. I&#39;m sure they can work out some arrangement that leaves Pluto as a planet, and lets number 10 become a planet, for the minute. But isn&#39;t it obvious that there are going to be tens if not hundreds of KBOs discovered in the coming decades as big and bigger than Pluto. Do we really need to have text books constantly changing?

I don&#39;t think so. I think 8 planets is a fine number of planets. Planets don&#39;t have to be defined by size, i really don&#39;t see a problem with defining them by location, which is what we&#39;ve been doing anyway isn&#39;t it? If not for their location, many of the moons of the gas giants would be classified as planets, but they aren&#39;t because of where they reside in the solar system. Same thing with the KBOs as far as I can see, because of their location, including Pluto, there&#39;s no need to call them planets, just confuses the issue. Just call them all KBOs and everything is pretty simple and easy to understand for all the laymen out there.

Having semantic arguments every few years about whether each new KBO is or should be classified as a planet really does nothing for Astronomy in the general community, just keeps on confusing everyone out there and turning them off the whole subject&#33; (Can&#39;t Astronomers ever make up their bloody minds?&#33;?)

As far as I can see, the &#39;Inner Solar System&#39; as a term should be redefined to include everything within the orbit of Neptune, whereas everything TN, can be referred to as the &#39;Outer Solar System&#39; Isn&#39;t it obvious that in terms of discovering items in our Solar System, we&#39;ve uncovered a far higher percentage of objects this side of Neptune than we have discovered the other side of Neptune. Over the coming years and decades as our resources become more powerful and refined, we are only going to keep discovering objects TN, more and more and more, and eventually we&#39;ll be aware of more objects TN than objects this side of Neptune. Don&#39;t know how long that will take, but it&#39;s a given, given that TN is a much larger space than this side of Neptune is.

But in terms of referring to objects as part of the Inner or Outer Solar System, I think it makes more sense to place that boundary at Neptune rather than where it is currently, the Asteroid Belt. What do you guys think of that redefining?

And one other thing for people who say that downgrading Pluto now means that we have to change textbooks and it&#39;s so much trouble. Trust me, in 500 years, the 20th century definition of Pluto as a planet will be regarded as an interesting historical blip that occurred due to our underdeveloped technological levels and lack of understanding of the broader Galactic system that we live in&#33; Nothing more&#33; Not a huge mistake

(Coming Soon)

www.solarcouncil.org

(A site dedicated to the sensible development, exploration & exploitation (exploiration) of the Solar System over the coming centuries)

cran
2005-Aug-02, 06:09 AM
Originally posted by julesy@Aug 2 2005, 12:35 PM
Do we really need to have text books constantly changing?

I don&#39;t think so...Having semantic arguments every few years about whether each new KBO is or should be classified as a planet really does nothing for Astronomy in the general community, just keeps on confusing everyone out there and turning them off the whole subject&#33; (Can&#39;t Astronomers ever make up their bloody minds?&#33;?)

And one other thing for people who say that downgrading Pluto now means that we have to change textbooks and it&#39;s so much trouble. Trust me, in 500 years, the 20th century definition of Pluto as a planet will be regarded as an interesting historical blip that occurred due to our underdeveloped technological levels and lack of understanding of the broader Galactic system that we live in&#33; Nothing more&#33;


julesy,

I think we do need to have textbooks constantly changing, otherwise it would mean that the science has become static, perhaps stagnant; I think it would be a sad day when there is nothing more to be discovered or written.

Semantic arguments are not intended for the general community; they are for bored PhD&#39;s and enthusiastic amateurs (like us); but don&#39;t worry about the community being turned off - the apparent popularity of reality television and soap operas indicates that the general community is interested in any argument/controversy/slanging match.

If anything, this debate has raised Astronomy&#39;s profile, not lowered it.

And in 500 years? The 20th century definition of anything might be regarded as suspect, due to our lack of understanding...assuming, of course, that we don&#39;t wipe ourselves out in the meantime...

aeolus
2005-Aug-02, 10:59 AM
Originally posted by John L@Aug 1 2005, 10:55 PM
What are the astrologers going to do if they make Rupert a planet? Are we going to find out what happens when Rupert is rising in Leo? Will Virgos suddenly become distant and sullen rather than compasionate? How will Rupert in opposition to Saturn effect your choice of careers? And why the heck didn&#39;t the astrologers know about Rupert in the first place??? :P
That&#39;s if it ever rises in Leo at all... with an orbital inclination of 41 degrees, it might only pass through but 2 zodiac constellations.

Jakenorrish
2005-Aug-02, 12:29 PM
Hi again JohnL,

I think that Douglas Adams&#39; idea that the planet be named &#39;Rupert&#39; is a wonderful idea. We should lobby for it now&#33;

On the subject of Pluto, I still disagree. We&#39;re talking about an object that has been a planet for more than 70 years. Culturaly, it will remain a planet, no matter what the IAU decides. The general public, media etc, will still say its a planet. I think that the scientific community must realise that yes, Pluto may be a Kuiper Belt object, and &#39;Rupert&#39; also is a KBO. However, if we follow this train of thought, neither Pluto or &#39;Rupert&#39; are planets, they are KBO&#39;s.

I understand perfectly the logic in your argument though I don&#39;t agree with the asteroid point as the time frame was considerably less in that instance wasn&#39;t it? Mine has no logic to it whatsoever. However foolish I may be, I will continue to call Pluto a planet, and will no doubt refer to &#39;Rupert&#39; as a planet. Most of the world&#39;s population will too. The IAU can waste their time arguing this point when they could be discovering other wonderful objects&#33;

I also celebrate the fact that this will make Astrologers look even more foolish. Yippee&#33;&#33; :lol:

burmese
2005-Aug-02, 12:51 PM
New York Times editorial on the subject:

http://www.nytimes.com/2005/08/02/opinion/02tue4.html

I agree with them, although I would not be upset if the IAU &#39;grandfathered&#39; Pluto as a planet while letting it fall short of their upcoming definition of a planet.

Nereid
2005-Aug-02, 12:57 PM
Names, names, and classifications&#33;

Jewitt&#39;s Kuiper Belt website (http://www.ifa.hawaii.edu/faculty/jewitt/kb.html) has as good a compilation of material as any (except that he hasn&#39;t updated it yet, for the recently announced discoveries).

There are two terms which seem to me to be quite useful: KBO (Kuiper Belt Object) and SDO (Scattered Disk Object). They distinguish quite nicely between (likely) mechanism for giving them the orbits they have today, and also don&#39;t get too bogged down with trying to distinguish comets from other objects.

About the only thing that I think is a bit unfair is that poor old Edgeworth&#39;s name has been dropped, and is now largely forgotten; for historically accuracy at least, it should be the EKB (http://star.pst.qub.ac.uk/~scb/kuiper.html) (Edgeworth-Kuiper Belt).

Anyway, within the EKB, there are many KBOs in &#39;resonance orbits&#39;; one of these is 3:2 with Neptune, and there are several KBOs in these orbits. The largest of these &#39;plutinos&#39; is Pluto.

DXT
2005-Aug-02, 01:17 PM
According to ancient languages scholar Zecharia Sitchin,the Sumerians had advanced knowledge of astronomy. knowing the existance of Uranus, Neptune and Pluto thousands of years before being officially dicovered. they also new of a tenth planet with a elliptical, orbit they called this planet, NIBIRU.

antoniseb
2005-Aug-02, 01:21 PM
Originally posted by DXT@Aug 2 2005, 01:17 PM
According to ancient languages scholar Zecharia Sitchin,the Sumerians had advanced knowledge of astronomy. knowing the existance of Uranus, Neptune and Pluto thousands of years before being officially dicovered. they also new of a tenth planet with a elliptical, orbit they called this planet, NIBIRU.
Hmmm. That&#39;s interesting DXT. I have studied some of the ancient astronomy of the Sumarians, and never encountered these references. Can you point me to the cuneiform tablets, or perhaps some secondary source that shows that they were aware of Uranus, Neptune, and Pluto?

Jakenorrish
2005-Aug-02, 01:30 PM
"Our culture has fully embraced the idea that Pluto is a planet and scientists have for the most part not yet realised that the term planet no longer belongs to them," says Michael Brown, one of the astronomers who discovered 2003 UB313.

His conclusion is simple: "From now on, everyone should ignore the distracting debates of the scientists. Planets in our solar system should be defined not by some attempt at forcing a scientific definition on a thousands-of-years-old cultural term, but by simply embracing culture. Pluto is a planet because culture says it is."


The above comes from the following article:

http://news.bbc.co.uk/1/hi/magazine/4737647.stm

John L
2005-Aug-02, 02:01 PM
I think the IAU defining a planet will settle the debate, and could change the status of Pluto... in the long run. If they decide to demote Pluto down to only one of the largest KBO&#39;s, and the largest Plutino, then that will become the academic definition and text books will start to change. For 99.9% of the people in the world they will either not notice or not care for some time to come. One day, 40 years from now, some grandfather will be arguing with his young grandson as he asks the little one if he knows all of the planet&#39;s names and the grandson stops at Neptune. The grandfather will explain that in his day Pluto was considered a planet, too, and no astronomer was going to convince him otherwise. But the little grandson will think grandpa is off his rocker or forgot to take his pills and that will be that. When our generation has died off then Pluto will cease to be remembered as a planet and the world will think the planets stop at Neptune. The only thing that could change Neptune being the last planet would be finding something big enough and in an orbit that fits the new definition of a planet, probably out between 150-500AU, but we&#39;re not there, yet.

Jakenorrish
2005-Aug-02, 02:15 PM
Fair points as always JohnL.

I think that the fact that Pluto has an atmosphere (yes I know it freezes out for some time in its orbit&#33;) will be taken into account when the IAU announces its decision. I&#39;d be surprised if they decide to do something as radical as downgrading Pluto&#39;s planetary status.

After all they&#39;ll be busier dealing with all the protesters carrying their &#39;Call it Rupert&#39; banners won&#39;t they?&#33;

rahuldandekar
2005-Aug-02, 03:29 PM
I&#39;m for the term planet becoming a mere historical term. Basically, my argument is the same that I&#39;ve been posting throughout this thread. Calling Pluto and Rupert (I&#39;m for Rupert&#33; :D) planets will group them into a category they don&#39;t belong to, and separate them from KBOs, a category they DO belong to.

If IAU does late the revolutionary step of downgrading Pluto&#39;s status, Everything will be clearer - There will be 4 Gas giants, 4 terrestrial planets, 100s of satellites, thousands of asteroids and KBO and comets.

Calling pluto a planet was a modern step - it ain&#39;t culture, because according to culture, there are only 6 planets - and it was wrong step, since it&#39;s size was overestimated.

I&#39;m sorry if my posts are repititive. :) :ph34r: :unsure:

John L
2005-Aug-02, 04:32 PM
Originally posted by rahuldandekar@Aug 2 2005, 09:29 AM
Calling pluto a planet was a modern step - it ain&#39;t culture, because according to culture, there are only 6 planets - and it was wrong step, since it&#39;s size was overestimated.
GREAT POINT&#33; We should all also remember, as rahuldandekar points out that, that the real definition of the word planet is "wandering star." The only real planets therefore are those that are visible to the unaided eye - Mercury, Venus, Earth, Mars, Jupiter, and Saturn. All other objects in the solar system, except the occasional flaring of a comet, are only visible with the aid of a telescope. Perhaps, rather than deciding a scientific definition of the word &#39;planet,&#39; the IAU should either chose another word in the lexicon or create an entirely new one. Call them worlds (major and minor), or gravitationally spherical differentiated bodies (GSDB&#39;s), or odments (major, minor, and gaseous).

Rupert is a minor world in the Edgeworth-Kuiper scattered disk region of the solar system. Rupert is GSDB in the... Rupert is a minor odment in the... We could ask the aliens monitoring us from there, but they lost their memories in an accident.

Hurricane
2005-Aug-02, 05:23 PM
I just saw where IAU committee member Alan Stern was quoted as saying he favored a definition of a planet as an object that orbits a star that is large enough to be round due to self-gravity, and is small enough to not have nuclear fusion at its core. This would boost the number of our planets to about two dozen.

I have a suspicion the IAU somehow uses 2003UB313&#39;s whopping 44-degree inclination against naming it a planet. Pluto, while having a relatively large inclination to the solar system&#39;s plane, is still much closer to the rest.

BTW, I&#39;m a first-time poster to this forum, yet long-time fan of the site. :)

TheThorn
2005-Aug-02, 05:38 PM
Originally posted by John L@Aug 2 2005, 04:32 PM

GREAT POINT&#33; We should all also remember, as rahuldandekar points out that, that the real definition of the word planet is "wandering star." The only real planets therefore are those that are visible to the unaided eye - Mercury, Venus, Earth, Mars, Jupiter, and Saturn.
I may be mistaken (and stand to be corrected), but I believe that under that ancient definition, there were seven planets: the six you named, minus the earth (which is not a wandering star, after all), plus the sun and the moon.

Obviously, we&#39;ve already changed that definition, back in Copernican times, to exclude the sun and moon, and include the Earth. What&#39;s wrong with allowing the definition to evolve in meaningful ways over time?

jhwegener
2005-Aug-02, 05:54 PM
Some questions to the classification debate: Is not our classification (main types of objects:stars, planets, moons, comets, asteroids)hopelessly anacronistic, fit for a period where the observational "instruments" was human eyes?
Would astronomers have invented those categories at all, if they were to start from scratch?
Stars are really different types of objects too, especially these years, were new faint types of objects are discovered.
Perhaps one day we have a truly universal system(based not on our solar system, but general picture, also interstellar objects). But we may still only have a faint idea about that. Are solar sytems perhaps more accidental and temporary than we tend to think? Could not at least the objects far from the center easily change partner? Will a more fundamental order be discovered, or will reality turn out to be rather "caotic"?

TheThorn
2005-Aug-02, 07:29 PM
I monitor the MPML (Minor Planet Mailing List), where Ortiz announced the discovery of 2003 EL61. Shortly afterwards Dave Tholen (who did an interview for UT earlier this year) pointed out that this was probably the same object that Brown et al. were presenting papers about in September, and supplied links to the abstracts of those papers, where they refer to it as K40506A. Wondering if any major news service had picked up on the story at that point, I googled K40506A. I got two hits (4 actually, from two sites) but both were just lists of numbers and such, from observation logs of telescopes being used in the research.

I didn&#39;t realize at the time that I was looking at data that was going to become the nub of a controversy. Apparently, what I was doing was "hacking" in Brown&#39;s mind, (he referred to it that way in an interview), although he seems to have backed away from that at this point. You see, there is enough information in those telescope logs to identify and locate the object, and claim credit for discovering it, since Brown et al. had not anounced it.

At the bottom of his page on 2003 UB313 (http://www.gps.caltech.edu/~mbrown/planetlila/index.html), he recounts the story from his point of view, and, as far as I can tell, it is an accurate recounting (althoug the amateur members of the MPML would likely put a different "spin" on it, in the conflict between open dissemination of information vs secrecy).

Some people have pointed out that Ortiz and company are actually presenting a paper at the same conference, so they would have had their attention drawn to Brown et al.&#39;s abstracts. Their discovery of 2003 EL61 came several days after those abstracts were published. Any time in between, a simple google of that publically revealed internal designation would have given them, or anyone else, the positional information needed to find it in a number of publically available archives of sky images.

Brown has been very careful not to accuse them of doing that. In fact, he has repeatedly stated he believes the timing of their discovery was just co-incidence. And I tend to agree, given that the other two, including 2003 UB313, the only one bigger than Pluto, were also revealed in those archives for anyone who was looking. If someone had figured it out that way, I would have expected them to claim the big prize, not the little one, as Ortiz did.

But it is all very interesting, adding a little intrigue to the story.

aeolus
2005-Aug-02, 07:36 PM
Well let me be the first to welcome your input. Hope to see you around here often, hurricane.

I think the orbital inclination and eccentricity are definately the two things with which I have the most problems. I think regardless of WHAT a body is, no matter it&#39;s mass or shape or size, it&#39;s BEHAVIOR ought to also be a distinguishing factor in it&#39;s classification. To this extent, Pluto and "Rupert" don&#39;t fit.

But I still think it should get a name. Rupert&#39;s cool...

John L
2005-Aug-02, 08:27 PM
I agree that "hacking" was the wrong word. It was more a data mining thing than anything else. Brown also seems to be insinuating that for future projects they will use different designations for their telescope time than for their publications. That shouldn&#39;t be hard to do.

What Brown doesn&#39;t acknowledge, though, are the accusations that he as his fellow researchers like to announce their discoveries while they are on the opposite side of the sun from Earth so that no one else can go looking for them and then trove their archives for the objects. I think that when they intended to announce these that would have been the case, and was the case for previous objects they have identified.

Duane
2005-Aug-02, 08:33 PM
A name has been submitted the the IAO, they will agree or reject it in the next couple of weeks (probably shorter, given the interest in the object).

Guest
2005-Aug-02, 09:20 PM
WE don&#39;t need a new planet,We can&#39;t afford to keep the one we got.

TheThorn
2005-Aug-02, 11:25 PM
LOL guest, you definitely have a point.

John L., I agree with the sentiment of your post. To place it in historical context, consider the following quote from Clyde Tombaugh&#39;s announcement of the discovery of Pluto (as transcribed by G. Bell, and posted on MPML today):


-In the discovery announcement for Pluto, the following can be found:

"LOWELL OBSERVATORY"
"Observation Circular"

"THE DISCOVERY OF A SOLAR SYSTEM BODY APPARENTLY TRANS-NEPTUNIAN"
-------------------------------------------------------

-Note that there is no claim of a planet in this portion of the announcement
though the effort was to find the planet predicted by Lowell.
-The announcement does indicate that the object was found in approximately
the position predicted by Lowell for a 9th planet.

-The announcement also includes the following:

"... In brightness the object is only about 15th magnitude. Examination of
it in the large refractor - but without very good seeing conditions - has
not revealed certain indication of a planetary disk... Thus far our
knowledge of it is based largely upon its observed path and its determined
rates of motion. These with its position and distance appear to fit only
those of an object beyond Neptune, and one apparently fulfilling Lowell&#39;s
theoretical findings."
-------------------------------

-And the final paragraph is, in my opinion, particularly indicative of the
attitude of the Lowell crew:

"While it is thus too early to say much about this remarkable object and
much caution and concern are felt - because of the necessary interpretations
involved - in announcing its discovery before its status is fully
demonstrated; yet it has appeared a clear duty to science to make its
existence known in time to permit other astronomers to observe it while in
favorable position before it falls too low in the evening sky for effective
observation."

" -V. M. SLIPHER"
"Flagstaff, Arizona"
"March 13, 1930 "
-------------------------------

And the copy of a photocopy in my possession includes Clyde Tombaugh&#39;s
signature.

In my opinion, this was a very modest and humble announcement.

The quotes above were transcribed from the photocopy, and I apologize in
advance for any typos I may have introduced.

Graham Bell


So, they did not call it a planet, and they rushed to get the information out there (in spite of the fact that they were the only people looking and didn&#39;t have to worry about being "scooped"), so that others could observe it before it got lost in the sun&#39;s glare. Exactly the opposite of the current discoverer&#39;s behaviour. Apparently, some do not feel the same "clear duty to science" that Tombaugh did.

There has been much discussion recently on MPML on this point. ;)

Karen M.
2005-Aug-03, 02:15 AM
Has anyone come across a link in regards to what the orbit of this "10th planet" is in relation to the other Planets? I would also be interested in seeing the orbits of Quaoar and Sedna included.

Thanks,
Karen

aeolus
2005-Aug-03, 02:27 AM
http://www.gps.caltech.edu/~mbrown/planetl...lila/index.html (http://www.gps.caltech.edu/~mbrown/planetlila/index.html)

remember the orbit is inclined around 40-45 degrees.

and here&#39;s some on Sedna:

http://www.gps.caltech.edu/~mbrown/sedna/

Jakenorrish
2005-Aug-03, 08:43 AM
On the strength of the fact that we have discovered planets orbitting stars in five days which are five times the size of Jupiter, I propose that we must go one step further and downgrade the Earth&#39;s status as a planet. Only gas giants should be called planets from now on.

It seems obvious that anything which is smaller than say Uranus will now be designated as a &#39;Weighty Rocky Outcrop Near Gas giants&#39; or W.R.O.N.G. for short.

After that we should designate Pluto as a Planet Regarded As Too Small or P.R.A.T.S.

Maybe we shouldn&#39;t. You can&#39;t just rewrite 70 years of history....

:lol:

rahuldandekar
2005-Aug-03, 01:32 PM
Yes we can. We rewrote 1500 years of history when Galelio discovered the principle of inertia.

Funny acronyms, Jake. But we discovered big gas planets because our techniques only allowed that. And I doubt that the earth is too small to be a planet. :)
As for Pluto, It does seem to share a lot more charecteristics wth KBOs than it does with "Planets".

Or maybe we just live in a solar system with rather small planets, and most of the planets out there are gassy giants and not "rocky outcrops". Maybe we just live on a W.R.O.N.G. world&#33;

Beholder
2005-Aug-03, 01:47 PM
First of all, I think, JohnL&#39;s idea of introducing the term "world" into the astronomical vocabulary is a very good idea&#33; Didn&#39;t think of that myself&#33;

Regarding classification questions:
We can classify solar system bodies into the following categories:

a) size/mass (i don&#39;t differ between these two since the densities of all bodies in the solar system are within one order of magnitude, so size and mass are approximately proportional for all solar system bodies)

B) position (rather inward or rather outward)

c) orbital eccentricity

d) WHAT it orbits

e) composition

f) whether it possesses an atmosphere.

Re a): An object of high enough mass to fuse hydrogenium is called "star" if it fuses protium too (or used to), or "brown dwarf" if it fuses deuterium only. If it&#39;s too light for that, but still possesses star like (= gaseous) composition, it&#39;s called a gas giant. Since a gas giant is a non-fusor, but significantly larger than an asteroid, it&#39;s definitely a planet. The trouble shows up when it comes to bodies
too small for gas giants, so i&#39;ll return to that later.

Re B): This shouldn&#39;t have any effect on how do you call it. The KBOs (at least the smaller ones) are KBOs because they reside in the Kuiper belt, but the term "asteroid" still applies. If an earth-size object, or even larger, is found out there, would you refrain from calling it a planet just because it is farther out than neptune???

Re c): Small objects of icy composition with high orbital eccentricity are usually called comets. But the term "comet" rather refers to the phenomenon of severe outgasing from bodies of asteroid size. There are bodies known which possess close to circular orbits and still show periodic outgasings, and they are also called "comets". Actually there is no naming convention yet based on orbital eccentricity, and that&#39;s good. For example, let&#39;s say, a gas giant of Saturn mass would have e=0.5 and therefore the distance to it&#39;s sun would change between 1 AU and 3 AU. Would you refrain from calling it a planet?

Re d): Anything which orbits a non-fusor is a moon, no matter what size. I would advocate to call only objects of at least 1 km diameter moons, so this definition should not include ring particles, but this is the wrong thread to discuss that. It can only be a planet (or asteroid) if it orbits a fusor (star). (This is also the wrong thread to discuss whether an Earth-mass object orbiting a brown dwarf should
be called a moon or a planet.)

Re e): This is the difference between gas giants and terrestrial planets. One could argue to base the definition of planet on whether an object is composed primarily of rock, but while Pluto wpuldn&#39;t be a planet then, Ceres would be.

Re f): Seems a good idea: to call a body large enough to hold an atmosphere a planet, and to call a body too small for that an asteroid. The problem is, that Mercury has no atmosphere, and Pluto has one at perihelion, but not at aphelion, so this is a dangerous point I would like to exclude from the discussion.

So after all, it all comes back to the size/mass point.
I agree to the point, that Pluto, the new object and other yet undiscovered large KBOs differ largely from terrestrial planets like Earth and Mars. But i think they differ even more from those small, mostly non-spherical objects we call asteroids in our part of the solar system.
Since my opinion still is, that any size boundary between planets and asteroids would be deliberate anyway, I hereby call for good ideas where to place the boundary except the size of Pluto&#33;

Perhaps it also would be a good idea to introduce a new class of bodies, large enough to achieve spherical form, but smaller than what we call planets, including bodies like Pluto, Sedna, Quaoar, Varuna, and Ceres. I think it would make sense to use the already-known term "planetoid", in opposition to "asteroid", for this group. The lower size limit would be those 700 km diameter required to get spherical, the upper size limit, dividing them from the group of "planets", could for example be the approximate size of Earth&#39;s moon, respectively a diameter of
3000 km. (I suppose there would be no discussion about calling Luna a planet if it was orbiting the sun instead, since it&#39;s way larger than Pluto.)

So the definition could be the following:
Dust: Anything too small to see with the naked eye.
Meteoroids (the boundary between meteoroids and asteroids is also not yet definded, I think): Anything large enough to be seen, but, for example, too small to "stand on", which means an upper size limit of diameter of about 10 m, or "smaller than a human", which would mean a maximum diameter of about 2 m.
Asteroids: Anything larger than that but with a diameter smaller than 700 km.
Planetoids: Diameters of 700-3000 km.
Planets: Diameters larger than 3000 km, but less than 13 (or 17, whatever, so it&#39;s a non-fusor) Jupiter masses.
Brown dwarves: Massive enough to fuse or have fused deuterium, but not protium.
Stars: Massive enough to fuse or have fused protium (to include white dwarves and neutron stars).
(This would include black holes, but I think they should be an extra group.)

By the way: I wonder if Brown got some "donation" from any TV station to name it "Xena"? And will he name the next KBO his team discovers "Gabrielle"? :D

IAU&#39;s policy on naming (minor) planets:

"names of a purely or principally commercial nature are not allowed"

Also:

"Objects sufficiently outside Neptune&#39;s orbit that orbital stability is reasonably assured for a substantial fraction of the lifetime of the solar system (so called Cubewanos or "classical" TNOs) are given mythological names associated with creation."

I looked up the minor planet&#39;s name list; for example "Wotan" (germanic chief god)and "Ymir" (giant, first living being in Norse mythology) are still free. (I&#39;m not sure though if they called one small Saturn moon "Ymir".)

Beholder
2005-Aug-03, 01:48 PM
oops, sorry, the sunglasses simley was not intended, I meant the letter "b".

mark mclellan
2005-Aug-03, 02:12 PM
What is the definition of a planet? is it a body that in its own right orbits a star with or without companions (that orbit around it first, and not the star) Or does it become more of a size issue? or an atmosphere issue? or possible life holding qualities? One of you space wizards out there should know what the definition is lol :D

antoniseb
2005-Aug-03, 02:21 PM
Originally posted by mark mclellan@Aug 3 2005, 02:12 PM
One of you space wizards out there should know what the definition is
We do know. The word "Planet" is not precisely defined with specific limits. There is talk that the IAU will be creating such a definition soon, but as of today, the word "planet" is a folksy expression with a loose meaning. Is Pluto a planet? Is Xena a planet? Is Titan a planet? Is Ceres a planet? Can a Brown Dwarf be a planet? Does it matter how the object was formed? Does it matter whether it orbits a star?

We may have answers to all these questions in a few months.

Guest
2005-Aug-03, 02:33 PM
Well, as we&#39;re all scientists, and we all have our own ideas, then I would expect that this will be reflected within the members of the IAU as well. The only solution is to compromise, which means that you all have to agree I&#39;m right as always&#33;&#33;&#33;&#33;
:P

Jakenorrish
2005-Aug-03, 02:34 PM
That last post was me by the way&#33;

imported_alan
2005-Aug-03, 03:38 PM
Demoting a planet wouldn&#39;t be unprecedented. Ceres was considered a planet when first discovered along with three others discovered shortly afterwards. They were demoted after 40 years when it became apparent that they were the first of a large group.

aeolus
2005-Aug-03, 03:43 PM
I have thoroughly enjoyed this topic. It has been SO active, and so pertinent. Can we collect the arguments together, just to summarize? I&#39;ll try my best to start:

And in the left corner, wieghing in at 287 (x 10^20) pounds, fighting as one of the "Major Nine", PLANET Pluto&#33; :

-Big enough that its gravity renders it spherical
-Has an atmosphere (seasonal, at that)
-Has a satellite
-Tidally locked with said satellite
-orbits the Sun

And as for Pluto NOT BEING A PLANET

-high eccentricity
-high orbital inclination
-composition more similar to KBOs than GGs
-size unlike the GGs, more like large KBOs

--------------------------------

This is the summary I got so far. I&#39;m just wanting to sort of keep track. Please add more if I&#39;ve missed any arguments. Or correct them if they&#39;re wrong.

Reina
2005-Aug-03, 06:14 PM
Originally posted by g-bomb@Aug 1 2005, 07:06 PM
<p.s> if we decide to name any new planets.. like the objects that are most similar to pluto and have orbits on the main plane.. we should name them after disney characters .. like goofy, donald, mickey, daffey.. that would be fitting i think
Iím not sure if youíre joking, but just in case you donít know the planets are named after roman gods, not cartoon characters.

Duane
2005-Aug-03, 06:25 PM
Excellent discussion guys&#33; My opinion is that Pluto should be demoted, as it was the first of a large class of objects, same as Ceres was some years ago. It is certainly not unprecedented that an object labelled a planet has been demoted, and the Kuiper Belt was only proposed by Kuiper and Edwards about 40 years ago. In other words, Tombaugh did not know there would be many more Pluto-type objects--in fact, maybe hundreds.

I think the discovery of this object is going to force the IAU&#39;s hand, and they are going to have to come up with an actual definition of "planet". Should be interesting to see what that description turns out to be.

Karen M.
2005-Aug-03, 06:27 PM
Thanks Aeolus&#33; Exactly what I was interested in&#33;

K

Hurricane
2005-Aug-03, 06:53 PM
Karen M. (and others),

Here&#39;s a nice graphic from Wikipedia showing the inclination:

http://en.wikipedia.org/wiki/Image:Orbit_o...0_July_2005.gif (http://en.wikipedia.org/wiki/Image:Orbit_of_2003_UB313_on_30_July_2005.gif)

If you click on the source NASA link you can manipulate the graphic for multiple perspectives&#33;

cheers

suitti
2005-Aug-03, 09:01 PM
Seen on a Bumper Sticker:

Good Planets Are Hard To Find

... probably environmentalist, but i came on it recently.

jules
2005-Aug-04, 12:10 AM
In regards to your contribution Beholder, i like your point about defining planetoid and planet. i like the concept, though not sure how easy it is to define a boundary between the two. i agree, any object that is large enough to form into a spherical shape should perhaps be distinguished from other lumps of rock floating around the Solar System, which are called Asteroids, and that objects large enough to form into spherical shapes, with of course the obvious examples of Ceres & Pluto, should be classified differently to these mere lumps.

In terms of defining a boundary between planetoids and planets though, using the moon as some sort of boundary is completely arbitrary, and in fact, i think any size you use to distinguish between planetoids and planets in the end becomes an arbitrary matter. thinking about the wider galactic continuum and the universe as a whole, it would seem likely that there are spherical shapes out there of every possible diameter going from 1000km across all the way up to the size of the earth, the size of jupiter, the size of some of the recently discovered gas giants discovered around other stars.

Because of that, any separation of planetoids or planets on the basis of diameter becomes arbitrary and pointless. i think in distinguishing the two you have to take into account all sorts of other factors, orbit, orbit eccentricity, what it orbits, uniqueness, maybe even atmosphere although i don&#39;t think that can really be used as a seperator given the number of moons that possess atmospheres makes that pretty much a useless differentiator.

i think the fact is, if Ceres was the only object orbiting in that region, in what is known as the Asteroid Belt, it wouldn&#39;t matter that&#39;s it&#39;s size is so diminished, it would be known as a planet even today, but the fact it shares that region with so many other objects of comparable sizes means it can&#39;t possibly be known as a planet as it&#39;s just part of a wider group.

As far as I can see, it&#39;s the same with Pluto. If it was the only object out there with a 2:3 resonance with Neptune, or the only object in the Kuiper Belt, then it would be known as a planet and i would support it remaining as a planet. Fact is though, there are many many objects out there with those characteristics, and we&#39;re only going to discover more and more of them over the coming years, and leaving Pluto classified as a planet when in fact it&#39;s just a member of another large group of objects makes little sense. in fact, makes absolutely no sense i would say.

So in terms of distinguishing planets from planetoids, i would argue that to be in fact classified as a planet as opposed to a planetoid, one of the key points is that the obect in question, as well as being spherical, has to have a unique orbit that is not shared with countless other objects of similar sizes.

That may sound like it mitigates against a double planet type system, and in a way it does. And in relation to Pluto, we are in fact talking about a double system are we not? Given that the centre of gravity between Pluto & Charon lies between each of those bodies, that is, as I understand it, a double system. That&#39;s not the issue with Pluto & Charon though, the issue is that there are countless other objects out there in 2:3 resonance orbits with Neptune which mean they are not particularly unique in their neck of the woods.

But, it does not mitigate against a double planet system at all. If Pluto & Charon were orbiting the sun in an orbit between the Earth & Mars for instance, then that would qualify as a double-planet system in my book, fact is, they don&#39;t though.

I guess this whole double-planet system area brings up another area for debate. If indeed the apologists for Pluto who are intent on it remaining as a planet are fair dinkum, shouldn&#39;t they also be arguing for Charon for instance to be upgraded to the status of a planet as well? Given the two are in a double-system out there, so doesn&#39;t that in fact mean that we already have 10 planets in our system as is?

Or am I wrong in assuming it&#39;s a double system? Someone please enlighten me?

thanks.

rocketblair
2005-Aug-04, 12:11 AM
Actually, it was Kuiper & Edgeworth. TNO (Trans-neptunian object) is often used instead of KBO, EBO or EKBO. Edgeworth proposed it first, but Kuiper more often gets the credit. I for one would prefer for the list of TNO&#39;s to grow as the objects are discovered, than for Pluto to be Left as a Planet and every new object at least as large as Pluto added as a new Planet. Other solar systems are bound to have diversity in their structure, so classifying the obects in those systems will have to wait until we have the technology to study them in detail. I think it&#39;s safe to say that TNO type (rock/ice) bodies won&#39;t be in close orbits around their stars, so our classifying them separate from the other bodies in our our system seems the right way to go in my opinion.

Sherlene Monique Williams
2005-Aug-04, 12:42 AM
[FONT=Arial][SIZE=7][COLOR=red][QUOTE]

You know what I think. I think pluto is a moon because of its size an orbit around the sun. It has a different angle orbit than the other planets. It also has a "moon" called Charon is Charon really a moon. Maybe pluto is one of neptune&#39;s moons or maybe pluto and charon is just debree from when the solar system was formed. And maybe this 10th planet is really the 9th planet. Think about it&#33;&#33;

rahuldandekar
2005-Aug-04, 02:13 AM
I agree with rocketblair. And I think we should let the word planet remain without a definition, because it is only one word, while there are many categories of objects in the solar system. And they two kinds of objects that would be grouped together in a definition would be completely diferent in composition: Gas Giants and Terestrial Planets. In fact, Some gas giants have terrestrial moons comparable in size to terrestrial planets.

So, I think Gas Giants and Terrestrials should be placed in different groups, instead of one group "planet". This will be particularly useful if we discover a very big planet (say, earth-sized) at 100-150 AU. We could call that "planet", as the word would not be rigid. And we could form a group within KBOs (If it is similar in compostition to a KBO) called "large KBOs" or something, and place it in that group.

rocketblair
2005-Aug-04, 02:54 AM
But where is the dividing line between Large KBO and Earth sized "planet" at 100-150 AU? An earth sized object out that far would surely be composed of mostly ices and some amount of rock. My opinion is that any object regardless of size outside the orbit of Neptune should be termed a KBO or TNO. The Rings of Saturn are made up of grains of dust up to house sized rocks, but they all are part of the ring system. All of the rock/ice bodies of the outer solar sytem would be part of the Kuiper belt or Ort Cloud. We have a lot to learn about what&#39;s out there, but there won&#39;t be any more gas giants or terrestrial type planets out there, or we&#39;ll have to scrap everything and start over&#33;&#33;&#33;&#33;

Josh
2005-Aug-04, 04:23 AM
This ~has~ been a great topic. Thoroughly good reading.

Does anyone know when the IAU will be announcing their definitive definitions?

For me on the one hand, Pluto should be removed from the planet list in light of these new findings. Otherwise, we&#39;ll soon have 30 planets. I&#39;m not sure if that would necessarily be a bad thing but we are, for some reason, sentimental towards the these planets we have at the moment.

It was mentioned earlier that Pluto was given a designation as a planet and an asteroid. Perhaps then all objects (that fit all other necessary criteria) that are bigger than Pluto should be designated as planets and all those smaller .. not planets. So Rupert (there you go JohnL ... it&#39;s catching on) is a planet and the other finds aren&#39;t.

I can&#39;t remember reading, but do these new objects have atmospheres?

cran
2005-Aug-04, 04:48 AM
Somewhere back there, jules raised the point about binary planets, citing Pluto and Charon (with the logical follow-on that Charon would then be the 10th planet, or perhaps, equal 9th?);

and just to throw a bit more muck into the fan - weren&#39;t there some who maintained that Terra and Luna are actually a binary system, rather than a planet/satellite system, based on mass ratios?

On another point, about reserving &#39;planet&#39; for only those objects we can see unaided; what are we calling those big round things orbiting other stars?

If an atmosphere is the decider (and I think Mercury was found to have a thin atmosphere of sodium), then wouldn&#39;t that make Saturn/Titan/Enceladus a triple planet system?

As for the point about stars; well, haven&#39;t we been learning a whole alphabet of stellar categories...O B A F G K M R N S . . .?

Why not a similar alphabet of sub-stellar catagories?

Don&#39;t mind me, I&#39;m just messin&#39; witcha&#33;

Josh
2005-Aug-04, 04:55 AM
Atmosphere alone wouldn&#39;t be the decider. There are a bunch of other criteria, not least of which would have to be that its main body of orbit is the sun. not another planet.

rocketblair
2005-Aug-04, 05:30 AM
Pluto would grow a tail just like a comet if it was somehow moved to the inner solar system, I can&#39;t fathom why it was ever given an asteroid number. Dual classification for Pluto just creates confusion and discord. I liken object class to the phrase "Birds of a feather flock together". The four inner planets although quite different in some ways, and the four gas giants, orbit basically in the same plane, in fairly circular orbits, I can&#39;t see why anyone would not want to call them Planets. Pluto has always been a misfit after the mass, composition and orbit were determined. For reasons stated repeatedly by many, it should be in the flock (TNO&#39;s) with the objects it shares the most characteristics with. Pluto is really the crux of this mess. Put it where it belongs, the beginning of the Kuiper belt, leave the 8 planets alone, they don&#39;t create any confusion. The discovery of objects in the KB and Ort Cloud will be exciting, but calling any of them "Planets", "Planetoids", "Planetesimals" or anything close to planet will not be conductive to the scientific community or the general public.

imported_alan
2005-Aug-04, 06:05 AM
Originally posted by Galactus@Jul 30 2005, 06:05 PM
Well, this discovery should certainly get the conspiracy theorists and alternate scientists going. Based on ancient Sumerian documents, etc., they have always maintained that another planet existed, one with a very large eccentricity and a very large period of revolution.

When Vesta reaches opposition near its perihelion it is visible to the naked eye. Maybe the Sumerians saw it.

imported_alan
2005-Aug-04, 06:08 AM
Originally posted by rocketblair@Aug 4 2005, 05:30 AM
Pluto would grow a tail just like a comet if it was somehow moved to the inner solar system, I can&#39;t fathom why it was ever given an asteroid number. Dual classification for Pluto just creates confusion and discord.
I don&#39;t believe Pluto has a number. There was some discussion of making it number 10000. It created so much uproar that they decided against it.

cran
2005-Aug-04, 06:17 AM
Originally posted by Josh@Aug 4 2005, 12:55 PM
Atmosphere alone wouldn&#39;t be the decider. There are a bunch of other criteria, not least of which would have to be that its main body of orbit is the sun. not another planet.
How does that work with binary or multiple planets which orbit a common centre of gravity whilst orbiting a star as a common group?

We could say that every object in the solar system is gravitationally bound to the sun, and therefore its main body of orbit is the sun...

The three largest terrestrial planets have &#39;tails&#39;, that doesn&#39;t make them comets.

Shoemaker-Levy 9 didn&#39;t have a tail, but it was no less a comet.

rocketblair
2005-Aug-04, 06:42 AM
Thanks Alan- My faith in the IAU is partially restored.

Cran- Venus Earth and Mars have tails? ones that stretch millions of miles like some Comets?

Shoemaker-Levy 9 had no tail because it never approched close enough to the Sun. I wasn&#39;t commenting on all cometary behavior.

I don&#39;t think you got the point of my post- If Pluto were to be moved to the inner solar system, it would look like a giant comet. This is just to illustrate the composition issue which adds to the other reasons why Pluto should be classified separately from the inner and gas giant planets.

Jakenorrish
2005-Aug-04, 08:12 AM
Yep, I&#39;m one of those who thinks Terra and Luna are a double planet system, which if Pluto remains a planet would probably also make it and Charon a double planet. There is an old thread in the forums where to sum it up we discussed about ratios.

I think that eventually planets will have similar &#39;classings&#39; as stars do now. With the discovery of extrasolar planets, and the fact that we&#39;re finding completely different and unexpected types of planet, terms like &#39;Binary planet&#39; and &#39;Gas Giant planet&#39; will become the norm, though Gas Giant is very common today.

Pluto should also be a type of planet. Maybe &#39;Kuiper belt planet&#39; would be a nice compromise, which would mean &#39;Rupert&#39; will also get that clasification&#33;

cran
2005-Aug-04, 10:33 AM
Originally posted by rocketblair@Aug 4 2005, 02:42 PM
Thanks Alan- My faith in the IAU is partially restored.

Cran- Venus Earth and Mars have tails? ones that stretch millions of miles like some Comets?

Yes, they do - not as spectacularly bright as with some comets, but driven by the same solar wind - part of the outermost layer of the atmosphere (the exosphere) is pushed away from the sun; and &#39;tail&#39; is the word used - in the case of Venus (the densest atmosphere) the &#39;tail&#39; stretches almost to the orbit of the Earth (about 25 million miles - what&#39;s that? times 1.6 for km), so yes, millions of miles.

Comet tails (the gassy ones) form from volatiles released from the body of the comet; planet &#39;tails&#39; form from the thin volatiles in the outer atmosphere - which, according to some (if not most) models, formed from degassing of the planet during, or shortly after, mantle differentiation; so they are really not that different.


Shoemaker-Levy 9 had no tail because it never approched close enough to the Sun. I wasn&#39;t commenting on all cometary behavior.

No, Shoemaker-Levy9 was well and truly close enough to form a tail - I was being a little bit unfair, there - in its earlier, single phase, SL9 would have had a normal comet tail; but when it broke up (and formed the &#39;string of beads&#39;) it lost most of its lighter volatiles; my point was that here was a defined comet which had lost its tail, but was no less a comet because of that...and it was still referred to as one comet, even though it was about a dozen pieces of dusty ice when it finally took the plunge.



I don&#39;t think you got the point of my post- If Pluto were to be moved to the inner solar system, it would look like a giant comet. This is just to illustrate the composition issue which adds to the other reasons why Pluto should be classified separately from the inner and gas giant planets.

No, I took the point about what Pluto would look like if moved close enough to the sun; and assuming that it is composed entirely of volatiles, it would certainly look like a rather spectacular (if diminishing) stable comet for a good few millenia. If, however, Pluto proved to have, for example, a silicate, or carbonsulfide, or ferrosilicate core, would that change things?

And if the cores of the ice giants (sorry... smaller gas giants) turn out to be the same composition as the KBOs, would that then preclude their status as planets?

Jakenorrish,

think that eventually planets will have similar &#39;classings&#39; as stars do now. With the discovery of extrasolar planets, and the fact that we&#39;re finding completely different and unexpected types of planet, terms like &#39;Binary planet&#39; and &#39;Gas Giant planet&#39; will become the norm, though Gas Giant is very common today.

I think you may be right; it already happens to a limited extent with planets (remember when it was &#39;inner&#39; and &#39;outer&#39;?, now it is more commonly &#39;terrestrial&#39; and &#39;giant&#39; or &#39;gas giant/ice giant&#39;) - even more so with asteroids (by location), and with &#39;zen&#39; meteors (those which choose to become &#39;one with the Earth&#39;), by location type and composition.

I would like to see a classification scheme for planets, perhaps based primarily on density/dominant chemistry, with secondary modifiers based on orbital regime (distance, inclination, eccentricity) - under such a scheme, Pluto, Rupert, and any others which may yet make themselves known, would be identifiable as planets made mostly of ice, and oddballs within (or even beyond) the KB (or its equivalent in another system), which may be important if we want to use the larger, more stable KBOs (like Pluto, Rupert, Sedna, etc) as stepping stones or communication relays on our way out of this system, and into another one.

Indeed, &#39;hot-jupiters&#39;, &#39;super-earths&#39;, terrestrial planets, gas giants, ice giants, carbon planets, whatever...would be readily identifiable (exo-planets may need a further modifier based on stellar type, if we want to know immediately whether the planet might fall within that system&#39;s &#39;habitable zone&#39;)


Yep, I&#39;m one of those who thinks Terra and Luna are a double planet system, which if Pluto remains a planet would probably also make it and Charon a double planet.

Let&#39;s hear it, then for Sol3a and Sol3b, and Sol9a and Sol9b&#33;
&#39;binaries rule, ok&#33;&#39;

burmese
2005-Aug-04, 12:31 PM
Well, if we are going to classify planet types, why not use the old Star Trek terminology "Class M" for very Earth-like planets, etc...I don&#39;t have the list but someone once made up nice definitions for all the letters of the alphabet, with planets assigned letters that are further and further away from M being less and less Earth-like.

John L
2005-Aug-04, 02:20 PM
Originally posted by cran@Aug 3 2005, 10:48 PM
And just to throw a bit more muck into the fan - weren&#39;t there some who maintained that Terra and Luna are actually a binary system, rather than a planet/satellite system, based on mass ratios?
The mass ratio is not what makes two objects a double system. In the Earth-Moon system the center (or foci) of the Moon&#39;s orbit are within the planet Earth itself. The Moon orbits around the Earth. In the Pluto-Charon system the center (or foci) of Charon&#39;s orbit is outside of the planet Pluto, and Pluto co-orbits Charon. Size has nothing to do with it. It&#39;s all orbital mechanics.

ToSeek
2005-Aug-04, 02:49 PM
Originally posted by John L+Aug 4 2005, 02:20 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (John L @ Aug 4 2005, 02:20 PM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-cran@Aug 3 2005, 10:48 PM
And just to throw a bit more muck into the fan - weren&#39;t there some who maintained that Terra and Luna are actually a binary system, rather than a planet/satellite system, based on mass ratios?
The mass ratio is not what makes two objects a double system. In the Earth-Moon system the center (or foci) of the Moon&#39;s orbit are within the planet Earth itself. The Moon orbits around the Earth. In the Pluto-Charon system the center (or foci) of Charon&#39;s orbit is outside of the planet Pluto, and Pluto co-orbits Charon. Size has nothing to do with it. It&#39;s all orbital mechanics. [/b][/quote]
On the other hand, isn&#39;t it the case that the Sun&#39;s gravitational influence on the Moon is greater than the Earth&#39;s, and that the Moon&#39;s track with respect to the Sun is always concave? One could make a case for Moon-is-planet that way.

John L
2005-Aug-04, 03:45 PM
Originally posted by ToSeek+Aug 4 2005, 08:49 AM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (ToSeek @ Aug 4 2005, 08:49 AM)</td></tr><tr><td id='QUOTE'>
Originally posted by John L@Aug 4 2005, 02:20 PM
<!--QuoteBegin-cran@Aug 3 2005, 10:48 PM
And just to throw a bit more muck into the fan - weren&#39;t there some who maintained that Terra and Luna are actually a binary system, rather than a planet/satellite system, based on mass ratios?
The mass ratio is not what makes two objects a double system. In the Earth-Moon system the center (or foci) of the Moon&#39;s orbit are within the planet Earth itself. The Moon orbits around the Earth. In the Pluto-Charon system the center (or foci) of Charon&#39;s orbit is outside of the planet Pluto, and Pluto co-orbits Charon. Size has nothing to do with it. It&#39;s all orbital mechanics.
On the other hand, isn&#39;t it the case that the Sun&#39;s gravitational influence on the Moon is greater than the Earth&#39;s, and that the Moon&#39;s track with respect to the Sun is always concave? One could make a case for Moon-is-planet that way. [/b][/quote]
The Sun&#39;s gravitational influence is the greatest of any object in the solar system, but No, the Moon is not a planet. The center of the Moon&#39;s orbit is within the Earth. That makes it a Moon. The only reason the Moon goes around the Sun is because the Earth does.

Karen M.
2005-Aug-04, 05:17 PM
Hurricane -

The link - the one for the NASA source - is completely awesome&#33; Just as a hint to anyone who wants to play with it, speed up time to "1 year" and click forward, backward, rotate the orbital plane, zoom in, zoom out... Oh, it&#39;s so wonderfully awesome&#33; I suggest anyone check it out&#33;

Thanks for the link&#33;

K

rocketblair
2005-Aug-04, 06:22 PM
Ok Cran- I guess I&#39;m spoiled when it comes to tails, I always think of Hale-Bopp and Hyakutake.

John L
2005-Aug-04, 06:29 PM
The IAU Working Group on Extrasolar Planets posted in 2001 and amended in 2003 their working definition of a planet, which you can see here (http://www.dtm.ciw.edu/boss/IAU/div3/wgesp/definition.html). Basically they say:

Originally posted by Working Group on Extrasolar Planets
Objects with true masses below the limiting mass for thermonuclear fusion of deuterium (currently calculated to be 13 Jupiter masses for objects of solar metallicity) that orbit stars or stellar remnants are "planets" (no matter how they formed). The minimum mass/size required for an extrasolar object to be considered a planet should be the same as that used in our Solar System.Well, the minimum used in our solar system is Pluto, so according to this working definition, regardless of orbits, formation, or eccentricity, anything that has more mass than Pluto and has not reached the mass of a brown dwarf is a planet, which would include Rupert (2003UB313).

The working group also says:

These statements are a compromise between definitions based purely on the deuterium-burning mass or on the formation mechanism, and as such do not fully satisfy anyone on the WGESP. However, the WGESP agrees that these statements constitute the basis for a reasonable working definition of a "planet" at this time. We can expect this definition to evolve as our knowledge improves.

John L
2005-Aug-04, 06:45 PM
Geoff Marcy and Paul Butler have their own definition of a planet (http://exoplanets.org/defn.html) out there, too.

A ``planet&#39;&#39; is an object that has a mass between that of Pluto and the Deuterium-burning threshold* and that forms in orbit around an object that can generate energy by nuclear reactions.

They also include some of the IAU&#39;s definition attempts and addendums...

aeolus
2005-Aug-04, 06:53 PM
That&#39;s a reasonable definition, but if they&#39;re gonna keep it like that, I&#39;ll only be happy if we start to introduce classes of planets. Venus, Jupiter, Ceres, and Rupert are all too different from each other to have the same classification. Sure, they fall under the same umbrella, but not enough to ignore being more specific.

GOURDHEAD
2005-Aug-04, 09:51 PM
Here (http://space.com/scienceastronomy/050802_planet_definition.html) is a discussion of planet definition. I hope their definition is able to handle the discovery of a Neptune sized object orbiting beyond 70AUs in a plane more than 23 degrees to the ecliptic.

John L
2005-Aug-04, 10:15 PM
I don&#39;t think an ice giant would present us with too much of a problem. They&#39;re only having issues with the grey areas - the little things the share their orbit with a whole bunch of other little things; the ones that border on brown dwarf mass; the free-floaters that don&#39;t even orbit a star. For some the 23 degree thing might throw them off, but I don&#39;t think it should. I mean, why is it required that all planets form in and remain along some sort of ecliptic. Someone else pointed out that it would be wrong to make a too restrictive definition based only on our own solar system until we get a bigger and better sample from the rest of the star systems.

rocketblair
2005-Aug-04, 11:19 PM
Originally posted by rocketblair@Aug 4 2005, 12:11 AM
Other solar systems are bound to have diversity in their structure, so classifying the obects in those systems will have to wait until we have the technology to study them in detail. I think it&#39;s safe to say that TNO type (rock/ice) bodies won&#39;t be in close orbits around their stars, so our classifying them separate from the other bodies in our our system seems the right way to go in my opinion.
John L- I hope you were refering to one of my earlier posts. While there will likely be many objects found orbiting other stars that differ significantly from the ones orbiting ours, we should also expect some that will be similar. My opinion is that the new obects being discovered should be included in a class that associates them with the other objects that they share the most characteristics with. Whatever that turns out to be. I like TNO just to avoid the kuiper/Edgeworth controversy. Other systems may have objects like these without a belt or cloud, but in any case, it will be quite a while before we can even study them. Classes of objects will need to be tweaked from time to time, but too many dual/cross classifications seems counterproductive to me.

cran
2005-Aug-05, 01:05 AM
Someone else pointed out that it would be wrong to make a too restrictive definition based only on our own solar system until we get a bigger and better sample from the rest of the star systems.
Good point, JohnL

TheThorn
2005-Aug-05, 02:55 AM
I don&#39;t think we&#39;ll be finding many "ice giants". All four gas giants are far enough from the sun to freeze the stuff they&#39;re made of, just check out their moons. If you get enough icy material together to make a giant, it will generate enough heat internally to be a gas giant.

So, let&#39;s take a look at the biggest objects in the solar system, by mass (excluding the one star):

Object Percentage of next larger
Jupiter
Saturn 30%
Neptune 18%
Uranus 85%
Earth 7%
Venus 82%
Mars 13%
Mercury 52%
2003UB313 5%
Pluto 71%
2004 DW 31%
Sedna 82%
(Many TNOs go here)
Ceres 23%
Pallas 40%
Vesta 90%
etc

There appear to be two "gaps" in this chain: One betweeen Uranus and Earth, and one between Mercury and Rupert. But the difference between giants and dwarfs is more obvious if you sort them into two groups, the ones mostly made of rock and the ones mostly made of volatiles. I&#39;ll just show the ratios this time:

Volatile Objects

Jupiter
Saturn 30%
Neptune 18%
Uranus 85%
UB313 0.02%
Pluto 71%
2004 DW 31%
Sedna 82%

Rocky Objects

Earth
Venus 82%
Mars 13%
Mercury 52%
Ceres 0.2%
Palas 40%
Vesta 90%

It&#39;s just a co-incidence that there are 4 of each type of giant (rocky and volatile) in our system, but the difference between a giant and a dwarf object is so blindingly obvious in both groups that the gap must be a real indication of a difference in kind, not just a difference in degree. Asteroids are not terrestrial planets, and KBO&#39;s are not gas giant planets.

That last sentence sounds so obvious to me that it is embarassing to type it. But it&#39;s the nub of this discussion. As soon as you realize that there are two types of planets, not just one, the line between planet and not planet becomes so obvious that you just can&#39;t miss it.

And it must indicate something about the way these objects develop.

GOURDHEAD
2005-Aug-05, 03:38 AM
I tried to help in another thread with:

The word "planet" means wanderer. Any object orbiting any star as seen from another object orbiting that same star will appear to wander against the background of stars.* I&#39;m willing to let comets retain their special category. but asteroids, even at the micro-gram mass level, become planets as noted. We could consider eliminating objects with masses at or below what would be totally consumed in the atmospheres of objects with equal to or greater than one earth atmosphere to simplify the bookkeeping.

For those who are interested in whether a stellar orbiting body is a planet or not I suggest categories of planets with earth as a standard as follows:

Hyper planet* * Above 10 jovian masses and below 100 jovian masses or the mass at which sustained fusion of hydrogen begins

Super planet* * one to <10 jovian masses

Large planet* * 10 earth masses to < 1 jovian mass

Planet* * * * * * * 0.5 to < 10 earth masses

Hypo-planet* * * 0.01 earth mass to < 0.5 earth mass

Micro-planet* * * < 0.01 earth mass

The above categories will provide a useful set of handles and preserve the meaning of the word planet as wanderer which each stellar orbiting object satisfies.

Asteroids would become non-stellar objects in their own galactic orbit.*
Micro planet should have a lower limit such as 10,000 KG and items with less mass would be planetesmals.

rahuldandekar
2005-Aug-05, 03:54 AM
Actually, if you make arbitary boundaries, it&#39;ll be difficult, because GOURDHEAD, Saturn and Jupiter will fall in different categories. And mass will be a problem too, because Pluto may have more mass than Rupert...

I think we should group similar composition planets within the same size range (like Uranus to Jupiter, but no Earth) together. That will be better.

rocketblair
2005-Aug-05, 03:56 AM
I&#39;m a Dust Speck but I orbit our Sun and would wander against the background of stars, can I please be promoted to Planet? Thanks&#33;

cran
2005-Aug-05, 04:20 AM
I don&#39;t think we&#39;ll be finding many "ice giants". All four gas giants are far enough from the sun to freeze the stuff they&#39;re made of, just check out their moons. If you get enough icy material together to make a giant, it will generate enough heat internally to be a gas giant.

Does anyone know a first reference to &#39;ice giants&#39;? I first encountered the term when astronomers were discussing Uranus and Neptune - there&#39;s a few mentions in that BBC series &#39;The Planets&#39; (C 1999); Unlike Jupiter and Saturn, Uranus and Neptune don&#39;t seem to be generating much internal heat - the lack of internal heat (and therefore less turbulence) allows for faster winds.

Sure, the difference is in the accumulated mass...

I think we will find plenty of &#39;ice giants&#39; (Urani and Neptunes), eventually.

The progessive percentage lists you provided probably do tell us something about the process of accretion in planetary discs (I note that a few satellites should probably rate in there, somewhere) - along the lines of Hal Levison&#39;s "it&#39;s a race, to eat up all the little guys&#33;"

It&#39;s just a co-incidence that there are 4 of each type of giant (rocky and volatile) in our system, but the difference between a giant and a dwarf object is so blindingly obvious in both groups that the gap must be a real indication of a difference in kind, not just a difference in degree. Asteroids are not terrestrial planets, and KBO&#39;s are not gas giant planets.
Agreed. The evidence so far seems to point to a difference in kind, or formational regime. Asteroids are, however, thought to be part of the remains of the stuff that accreted to form the terrestrial planets, and KBOs likewise for the gas/ice giants.

Jupiter and Saturn formed in a different kind of &#39;goldilocks&#39; zone - far enough from the sun for substantial bodies of volitile ices to remain solid, but close enough for lots of solar orbits (they had many more &#39;sweeps&#39; of the disc compared with the more distant protoplanets) - enough to accumulate sufficient mass to then draw a fair bit of the primordial hydrogen, causing them to swell quite rapidly, and to effect what was available for/happening to their neighbours.

Gourdhead, my understanding of &#39;planetesimals&#39; means objects which are pre-cursors to planets; part of the process of planetary accretion - larger, differentiating, planetesimals which accumulate smaller objects are sometimes called &#39;protoplanets&#39;, and if they don&#39;t do something silly (like crash into another protoplanet; get tossed into the star; or get flung out of the system altogether), they are considered planets.

cran
2005-Aug-05, 04:21 AM
Originally posted by rocketblair@Aug 5 2005, 11:56 AM
I&#39;m a Dust Speck but I orbit our Sun and would wander against the background of stars, can I please be promoted to Planet? Thanks&#33;
you just keep doing what you are doing...you&#39;ll be a planet before you know it&#33; :D

rocketblair
2005-Aug-05, 04:35 AM
I&#39;m sure I read somewhere that Saturn&#39;s winds are tops at around 1000 mph, however that may change (something about the planet&#39;s axial tilt) in a few years.

cran
2005-Aug-05, 06:16 AM
Originally posted by rocketblair@Aug 5 2005, 12:35 PM
I&#39;m sure I read somewhere that Saturn&#39;s winds are tops at around 1000 mph, however that may change (something about the planet&#39;s axial tilt) in a few years.
Again, the easiest reference I can point back to is the scientists on &#39;The Planets&#39; talking about their findings from the Voyager experience. One said, &#39;Saturn&#39;s winds were already going at 1000 (miles? or kilometres?) per hour; but instead of finding slower winds as we went further out, the winds got faster&#39; He went on to explain about the internal heat in Jupiter and (less so) in Saturn created turbulence which actually slowed the winds down; with even less internal heat and turbulence in Uranus and Neptune, there was nothing to slow the atmosphere, and the winds just kept getting faster and faster, with Neptune having the fastest (but not necessarily the strongest) winds of all.

PS- See, you&#39;re an asteroid already&#33; :D

rocketblair
2005-Aug-05, 11:13 AM
Cran- I found a site that compares wind speeds of the gas giants

Neptune 2000 k/hr
Saturn 1800 k/hr
Uranus 600 k/hr
Jupiter 450 k/hr

Why U and J are slower they don&#39;t say. Jupiter has the greatest internal heat but the slowest winds, whazzup with that? I&#39;ll do some more surfing later, maybe I can get the answer.

rocketblair
2005-Aug-05, 11:15 AM
Oops, Disregard the last part of my post, I need some sleep. Later

cran
2005-Aug-05, 12:18 PM
Originally posted by rocketblair@Aug 5 2005, 07:13 PM
Cran- I found a site that compares wind speeds of the gas giants

Neptune 2000 k/hr
Saturn 1800 k/hr
Uranus 600 k/hr
Jupiter 450 k/hr

Why U and J are slower they don&#39;t say. Jupiter has the greatest internal heat but the slowest winds, whazzup with that? I&#39;ll do some more surfing later, maybe I can get the answer.
thank you, rocketblair, and sleep well...you&#39;ll most likely be a planet tomorrow&#33; :)

Well, the figures there suggest something else is happening - it almost looks the values for Saturn and Uranus have been switched, but even that wouldn&#39;t be quite right; Jupiter and Neptune are close to values I&#39;ve come across before (but couldn&#39;t retrieve when I needed them - typical&#33;)

Of course, average windspeeds on these planets vary according to rotational latitude...diminishing towards the poles...that might explain Uranus...ah well, sooner or later, one of us will find some widely accepted results....

BUT - casting my eyes up to the title, we do seem to have wandered somewhat off-topic <_<

Tenth planet discoveries.....please (and sorry for the side-trip :ph34r: )

aeolus
2005-Aug-05, 01:24 PM
Its always neat looking back on things to see what people thought of something before it got controversial or big in the news. In all the hype of Rupert, some may be looking at the situation too specifically in regards to Rupert. Let&#39;s look at the planet argument before all this happened, when it was just a hypothesis that there would be a body more massive than Pluto discovered further out:

http://science.nasa.gov/newhome/headlines/...st17feb99_1.htm (http://science.nasa.gov/newhome/headlines/ast17feb99_1.htm)

John L
2005-Aug-05, 01:47 PM
Originally posted by cran@Aug 5 2005, 06:18 AM
BUT - casting my eyes up to the title, we do seem to have wandered somewhat off-topic <_<
Actually we&#39;re right no topic. Whether Rupert should be considered the 10th planet is a big part of this discussion. Right now, its just the largest known KBO/TNO. It is very valid to discuss whether its being larger than Pluto should qualify it for official planethood.

And I did mean your post rocketblair. Cheers&#33;

rocketblair
2005-Aug-06, 12:23 AM
Cran- Going off topic can be wind aided :lol:

Can&#39;t wait to see how this 10th Planet thing comes out as far as the IAU. One thing is for sure, you can&#39;t please everyone. My guess is they will decide on dual classification, which bothers me a lot, but may satisfy the most people. I guess that way it avoids the shock of suddeness and leaves a way to regress without as much embarassment.

cran
2005-Aug-06, 01:19 AM
Originally posted by aeolus@Aug 5 2005, 09:24 PM
Its always neat looking back on things to see what people thought of something before it got controversial or big in the news. In all the hype of Rupert, some may be looking at the situation too specifically in regards to Rupert. Let&#39;s look at the planet argument before all this happened, when it was just a hypothesis that there would be a body more massive than Pluto discovered further out:

http://science.nasa.gov/newhome/headlines/...st17feb99_1.htm (http://science.nasa.gov/newhome/headlines/ast17feb99_1.htm)

It has been proposed to assign Pluto a number in a technical catalogue or list of such Trans-Neptunian Objects (TNOs) so that observations and computations concerning these objects can be conveniently collated. This process was explicitly designed to not change Pluto&#39;s status as a planet." - from the article.

Thanks, aeolus. I don&#39;t really see any problem with objects having multiple status - eg, Pluto; planet Sol9a, TNO-001a, &#39;oddball&#39;, etc...

Depending upon how fine one makes the distinctions, it can be argued that every planet/satellite/&#39;big roundish thing&#39; we know about, is unique in some way...after all, Sol3a, Terra, Earth is the only one we know that has this massive infection called life...

Ah, JohnL, that&#39;s exactly what I meant (and part of the fault was mine) - we had strayed from &#39;whether Rupert is Sol10&#39; or not, and if not, why not? And the concurrent issue of whether Pluto ever should have been Sol9 (or Sol9a) at all - perhaps Pluto gets dropped, and Rupert becomes Sol9?

rocketblair, you&#39;re right - but we must be careful to distinguish &#39;a breath of fresh air&#39; from &#39;a lot of hot air&#39; :)

rocketblair
2005-Aug-06, 01:47 AM
Originally posted by cran@Aug 6 2005, 01:19 AM
And the concurrent issue of whether Pluto ever should have been Sol9 (or Sol9a) at all - perhaps Pluto gets dropped, and Rupert becomes Sol9?


Cran- If Pluto is dropped, then wouldn&#39;t Rupert face the same fate when an even larger body is found? Sol 9 or whatever could wind up changing many times, that would be a unfortunate chain of events.

I&#39;ve always thought Pluto deserved 9th planet status even though it seemed a misfit in the outer solar system, until 1992 when other obects smaller but similar in most other ways started to be found.

Just my opinion, always like hearing opposing views :rolleyes:

cran
2005-Aug-06, 04:15 AM
Originally posted by rocketblair+Aug 6 2005, 09:47 AM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (rocketblair &#064; Aug 6 2005, 09:47 AM)</td></tr><tr><td id='QUOTE'><!--QuoteBegin-cran@Aug 6 2005, 01:19 AM
And the concurrent issue of whether Pluto ever should have been Sol9 (or Sol9a) at all - perhaps Pluto gets dropped, and Rupert becomes Sol9?


Cran- If Pluto is dropped, then wouldn&#39;t Rupert face the same fate when an even larger body is found? Sol 9 or whatever could wind up changing many times, that would be a unfortunate chain of events...
Just my opinion, always like hearing opposing views :rolleyes:[/b][/quote]

:D Nailed it in one&#33; rocketblair, well done&#33; :D

milly
2005-Aug-06, 06:32 AM
hey why don&#39;t we call it "PLANET X"??? It is the tenth planet and during "GENERATION X"&#33;&#33;&#33; I thought the scientist who found it got to name it after himself so you know he&#39;s not going to name it goofy... darn I wish it was Dr. X that found it...

pooria
2005-Aug-08, 07:11 AM
Hello,
What is the name of the tenth planet?




Religious reference removed. -Matthew

cran
2005-Aug-08, 08:21 AM
Officially? Not decided or announced yet...
In some of the discussions going on here at UT - it&#39;s Rupert&#33; :)

Jakenorrish
2005-Aug-08, 08:50 AM
Any news from the IAU on this yet? Thought they were deciding by the end of last week whether Pluto stays a planet....

John L
2005-Aug-08, 04:26 PM
No IAU announcement that I can find. I guess they still haven&#39;t gotten enough members to agree on the dirty details, yet...

cran
2005-Aug-08, 11:52 PM
Originally posted by John L@Aug 9 2005, 12:26 AM
No IAU announcement that I can find. I guess they still haven&#39;t gotten enough members to agree on the dirty details, yet...
What are the odds that such a decision will be deferred until the probe ( :blink: what&#39;s its name?) gets there in a few years and sends back some yummy data and images? :mellow:

rocketblair
2005-Aug-09, 02:55 AM
The New Horizons mission is to launch from mid January to mid February 2006 and get to Pluto in July 2015. By then there will have been so many new objects discovered and looked at by better telescopes, hopefully we will have the classes and names all worked out long before the probe gets there. Nothing like a close flyby for the yummy stuff though...Right on :P

aeolus
2005-Aug-09, 04:54 AM
Originally posted by cran@Aug 8 2005, 11:52 PM
What are the odds that such a decision will be deferred until the probe ( :blink: what&#39;s its name?) gets there in a few years and sends back some yummy data and images? :mellow:
Odds are pretty good against that. New Horizons get to Pluto around 1015, and the KBOs around 2020. Im sure they&#39;ll have worked this out by then

cran
2005-Aug-09, 08:05 AM
New Horizons&#33; >smack forehead< :wacko: that&#39;s the one&#33;....er, I knew that... :unsure:

So, long odds on a long deferral, huh? Okay.

Jakenorrish
2005-Aug-09, 08:32 AM
No IAU announcement that I can find. I guess they still haven&#39;t gotten enough members to agree on the dirty details, yet...

I expect they are awaiting the outcome of our debate before they make a decision JohnL&#33;&#33;&#33;&#33; :P

Planetwatcher
2005-Aug-09, 09:58 AM
I kind of like GOURDHEADs idea of catagories, but perhaps fewer in the interest of having less confusion. So perhaps a few alterations, because as rahuldandekar correctly pointed out, Jupiter and Saturn would be placed in seperate catagories.
Mars and Mercury would become hypo-planets, and Ruppert, and Pluto microplanets.

That makes 6 catagories just in our Solar System. It&#39;s enough work getting school kids to even learn the planets names, much less all these catagories.
I would like to suggest the following...

Super planet Above 2 jovian masses and below the mass at which sustained fusion of hydrogen begins (in theory about 13 to 15 jovian masses)

Large planet 2 earth masses to < 2 jovian masses

Planet 0.02 to < 2 earth masses

Micro-planet < 0.02 earth mass

This comfortably covers most known exo-planets in the large or super catagories.
All four of our gas giants are in the large catagory.
Earth down to at least Mercury are planets. I think Pluto, and Rupert will barely make it too.
Sedna and smaller (I think) will all fit into the micro catagory.

But this reduces our known Solar system planets from 6 to 3, and perhaps even 2 catagories. A lot easier to remember and teach to others.

rocketblair
2005-Aug-09, 10:26 AM
Originally posted by Planetwatcher@Aug 9 2005, 09:58 AM

Mars and Mercury would become hypo-planets, and Ruppert, and Pluto microplanets.


Earth down to at least Mercury are planets. I think Pluto, and Rupert will barely make it too.

Ok, so Mercury is both a hypo-planet and planet, and pluto is both a micro-planet and planet. I hate dual classification, but it looks like I&#39;ll have to live with it.

rocketblair
2005-Aug-09, 10:29 AM
Oops- after more careful reading, those are two different proposals- my bad :wacko:

aeolus
2005-Aug-09, 01:42 PM
You think this is confusing? Wait until TPF, etc start bringing back pictures of crazy planetary systems we&#39;ve never dreamed of.

I think classifying the planets specific to our system is fine. In this whole "mass based " system you&#39;re propsosing, you&#39;re saying Jupiter and a 6-Jupiter mass Hot Jupiter orbiting some other star at 0.04 AU have the same last name? They might be related, but I&#39;d say they couldn&#39;t be more than step-siblings. There&#39;s too much different with them.

I like our system now - Terrestrial Planets, Inner minor planets (asteroids), Jovian / GGs, KBOs, etc... Makes sense to me, we&#39;ll just have to say Pluto isn&#39;t a scientific planet now. I don&#39;t know the big fuss - I still eat tomatoes as one of my 5-10 vegetables a day, even though the biologists tell me it&#39;s a fruit.

John L
2005-Aug-09, 02:59 PM
New Scientist on their website has a Name the 10th Planet (http://www.newscientistspace.com/article/dn7811) link with a list of the top 10 names so far offered, and RUPERT is listed as #5&#33;&#33;&#33; Persephone, the real name of Rupert, is listed as the #1 choice and Bob comes in at #6. :P


5. Rupert

It might seem like an unlikely name for a planet, and it probably would be. But in the fourth book of the Hitch-hikers Guide to the Galaxy ďtrilogyĒ - Mostly Harmless - author Douglas Adams describes a tenth planet around the Sun: ďThe planet was named Persephone, but rapidly nicknamed Rupert after some astronomer&#39;s parrot - there was some tediously heart-warming story attached to this - and that was all very wonderful and lovely.Ē

Tinaa
2005-Aug-09, 03:29 PM
9. Cerberus

Cerberus is the three-headed beast that guarded the gates of Hades (the Greek underworld). Alex Ijzerman, of the Netherlands, says: ďIn mythology Cerberus is the guard-dog of the Greek underworld. Heís the solar system&#39;s guard dog, you could say. Beyond it lies undiscovered country into which we are unable to pass at this moment.Ē

I like this one keeping with mythology.

Or...

Terminus - god of boundaries

Janus - god of gates

Lima - goddess of thresholds

Necessitas - goddess of destiny

aeolus
2005-Aug-09, 04:02 PM
We can compromise. How about Rupertus ?

cran
2005-Aug-09, 11:11 PM
Originally posted by aeolus@Aug 9 2005, 09:42 PM
You think this is confusing? Wait until TPF, etc start bringing back pictures of crazy planetary systems we&#39;ve never dreamed of.

I think classifying the planets specific to our system is fine. In this whole "mass based " system you&#39;re propsosing, you&#39;re saying Jupiter and a 6-Jupiter mass Hot Jupiter orbiting some other star at 0.04 AU have the same last name? They might be related, but I&#39;d say they couldn&#39;t be more than step-siblings. There&#39;s too much different with them.

I like our system now - Terrestrial Planets, Inner minor planets (asteroids), Jovian / GGs, KBOs, etc... Makes sense to me, we&#39;ll just have to say Pluto isn&#39;t a scientific planet now. I don&#39;t know the big fuss - I still eat tomatoes as one of my 5-10 vegetables a day, even though the biologists tell me it&#39;s a fruit.
UGTR*&#33;, aeolus...what was it..."stranger than we can imagine.."?
I&#39;d still like to see something based on mass/dominant chemistry with modifiers based on orbital regime...then by it&#39;s classification, we&#39;ll know if it&#39;s a &#39;hot jupiter&#39; or a &#39;super-earth&#39;....or whether it&#39;s a small icy outer planet or big round KBO...maybe. <_<

Jakenorrish
2005-Aug-10, 08:24 AM
Well its with a heavy heart and after much soul searching that I must concede defeat in the &#39;Is Pluto a planet&#39; debate. I will give my reasons for my complete u turn&#33;

I think that the thing that I (perhaps foolishly) overlooked in my original arguement is the orbit. The easiest way to tell the difference between our planets and other objects is their orbit. Pluto and Rupert (It may be no.5 in New Scientist, but I reckon its got to be no.1 on Universe today&#33;) have highly erratic orbits when you compare them to the other planets in our solar system. It is fairly easy to use this as the deciding factor when choosing if something is a planet or not.

Sentimentality has no place in science and the advancement of knowledge, so I own up, I was wrong&#33;&#33;

cran
2005-Aug-10, 09:22 AM
Originally posted by Jakenorrish@Aug 10 2005, 04:24 PM
Well its with a heavy heart and after much soul searching that I must concede defeat in the &#39;Is Pluto a planet&#39; debate. I will give my reasons for my complete u turn&#33;




:o No&#33; Don&#39;t do it, Jakenorrish&#33; If you make a complete U turn at this speed, the g-force will overwhelm you&#33; :o


I think that the thing that I (perhaps foolishly) overlooked in my original arguement is the orbit. The easiest way to tell the difference between our planets and other objects is their orbit. Pluto and Rupert (It may be no.5 in New Scientist, but I reckon its got to be no.1 on Universe today&#33;) have highly erratic orbits when you compare them to the other planets in our solar system. :blink: erratic?
eccentric, perhaps :wacko: .... &#39;inclined&#39; to see the whole system a bit differently, perhaps (on their own &#39;plane of existence&#39;, perhaps) B)...but erratic? :blink: that, I didn&#39;t know... :unsure:
It is fairly easy to use this as the deciding factor when choosing if something is a planet or not. Well....maybe :unsure:
...until some of those really big round things turn up somewhere (around another star, perhaps) with really wild orbits (like rotation in 2 axes - or tumbling) :lol: ...eccentric, inclined, or even "off the planet" - so to speak...
Sentimentality has no place in science and the advancement of knowledge, so I own up, I was wrong&#33;&#33; :( Damn&#33;, and I was really getting to like Rupert, too... :(

Wait a minute...isn&#39;t Mercury kind of &#39;inclined&#39; much more (like an OOM) than the other terrestrial planets? <_<
Doesn&#39;t Uranus rotate at something like 85 degrees to the ecliptic? <_<
Doesn&#39;t Venus rotate backwards (and way too slowly)? <_<
Doesn&#39;t Saturn have an average density less than water? <_<
Doesn&#39;t Terra have a moon that seems way too big for it&#39;s size? <_< and an amazing variety of self-replicating thingies all over it? <_<
So, can&#39;t we cut some slack to the &#39;erratic&#39; little guys? :huh:

Come back, Jakenorrish&#33; All is forgiven&#33; :(

rahuldandekar
2005-Aug-10, 11:19 AM
Oh no, Rain of smileys&#33;&#33;&#33;&#33;

Well, Cran&#39;s right, we should cut some slack to the "erratic". But if an object is in the KBO or not can be decided by it&#39;s orbit, itf it&#39;s "erratic", it&#39;s probably in the KB. Because almost all objects in the KB have highly eccentric orbits.

aeolus
2005-Aug-10, 11:27 AM
Everyone remember that the controversy/debate is about the scientific meaning of a planet. Pluto, no matter what IAU says in the coming weeks, will no change Pluto being a planet in most people&#39;s minds. For most, a planet is a big round rock orbiting the sun that astronomers look at. It won&#39;t have such the dramatic impact that some think it might.

Most people won&#39;t give much thought to it. No one, after all, cares about how bacteria and viruses come from two totally different domains of life. All they care about is how they now have to go buy some chicken soup and call their boss in the morning.

And for those that do, they&#39;ll take their sides. Most of those will have a loyalty to planetness or non-planetness of Pluto, just like I cheer for my home team. But it doesn&#39;t make a difference, cause in the end I just enjoy seeing a game of football, and spending a night stargazing.

Then there might be a few fanatics that go and "start the riots" after the game of planet classification, but less harm will be done; they&#39;ll only ever say some nasty things on a forum and eventually get banned.

Its still called Rupert though.

Jakenorrish
2005-Aug-10, 12:03 PM
Exactly rahuldandekar, which is in the main why I have changed my mind. Plus Sir Patrick Moore has changed his mind which is always an influence on my fickle brain&#33;

Seriously though. Looking at the models of our solar system, it is quite obvious that Pluto, Rupert et al are Kuiper belt objects and should be labelled as such. I earlier suggested the compromise of &#39;Kuiper Belt Planet&#39; and think this would suit us all.

I wonder if there&#39;s an even bigger KBP than Rupert out there? Yes it is definitely called Rupert&#33;&#33;

John L
2005-Aug-10, 02:30 PM
Jakenorrish,

You&#39;re allowing your provincial nature to overcome our intelect&#33; We are used to planets basically sticking close to the ecliptic, but that doesn&#39;t make it the natural order of the universe. The various influences that affect the formation of planets can cause many changes in their orbits relative to the disk from which they formed. As has been said, the definition of the word planet should not be limited to just what we see here in our own solar system, but should encompass all of the possibilities we may encounter throughout the rest of the galaxy as well. And highly vary orbit inclinations is one that should not preculde planet-hood, and neither in my opinion should high eccentricity. Remember that all of the planets have some eccentricity and inclination to the ecliptic because we provincially measure it from Earth&#39;s perspective. Measure it from Rupert and the Earth&#39;s orbit looks very odd indeed&#33; B)

cran
2005-Aug-10, 05:21 PM
rahuldandekar:
Oh no, Rain of smileys&#33;&#33;&#33;&#33;
Sorry... -_-

aeolus:
No one, after all, cares about how bacteria and viruses come from two totally different domains of life. All they care about is how they now have to go buy some chicken soup and call their boss in the morning...Its still called Rupert though.
Jakenorrish:
I earlier suggested the compromise of &#39;Kuiper Belt Planet&#39; and think this would suit us all. I wonder if there&#39;s an even bigger KBP than Rupert out there? Yes it is definitely called Rupert&#33;&#33;
John L:
Measure it from Rupert and the Earth&#39;s orbit looks very odd indeed&#33;

Right on, guys&#33; :D

Duane
2005-Aug-10, 09:23 PM
The planet is currently called Xena by the people who discovered it, but I understand the IAU is considering what its name should be.

rocketblair
2005-Aug-10, 10:52 PM
Originally posted by John L@Aug 10 2005, 02:30 PM
As has been said, the definition of the word planet should not be limited to just what we see here in our own solar system, but should encompass all of the possibilities we may encounter throughout the rest of the galaxy as well.
Of course, we can&#39;t be THAT patient in working out a definition. I just think using too many modifiers to the word planet would cause unneeded confusion, as would too many other new class names that might better decribe the characteristics of the object. If someone wants to know what "kind" of object it is (detailed description) they can always look it up. As I said before, with the rate of discovery speeding up, we need reasonable simplicity to avoid being overwhelmed with yearly (or even perhaps monthly) changes that we might be faced with later when we can study other solar system&#39;s objects with greater detail. While the configurations of other systems will most likely be pretty varied, the compositions of the planets themselves should be similar to ours (rocky w/or w/o atmospheres, gas, ice) the main difference being the type of gas, ice, etc. As Carl Sagan said, we&#39;re made of star stuff, and so are the other systems, so it&#39;s basically the same elements, just different amounts coming together by the forces involved in formation. On a trip to NY recently, I stopped by the Hayden Planetarium to see the Hall of Planets, that I learned left Pluto off of the list of Planets. I sent an e-mail to Dr Neil DeGrasse Tyson, famous Astrophysicist and Director of the Planetarium, and got a response from him concerning Pluto&#39;s status. His words only strengthend my opinion that the icy bodies beyond Neptune should not be called Planets. Yes, if they all were called planets it would be simpler, but the designation TNO would not be too much for even the general public to understand, and does the trick scientifically to distinguish them from the other 8 planets, which are called that with no confusion. YES, there may be some tweaking in the nomenclature later, but for now this seems simple enough and won&#39;t require a complete overhaul like a super complicated scheme with dual classifications and the like. OK, sorry about the length... can you tell I&#39;m passionate about this subject? :D

TheThorn
2005-Aug-11, 12:18 AM
Originally posted by rahuldandekar@Aug 10 2005, 11:19 AM
Well, Cran&#39;s right, we should cut some slack to the "erratic". But if an object is in the KBO or not can be decided by it&#39;s orbit, itf it&#39;s "erratic", it&#39;s probably in the KB. Because almost all objects in the KB have highly eccentric orbits.
"Because almost all objects in the KB have highly eccentric orbits."

Actually, this is not correct. TNOs come in a variety of "flavours", and the ones known as Classical KBOs, (or Cubewanos, after 1992 QB1, the first KBO discovered) have orbits that are relatively circular, and near the ecliptic. QB1 itself, for instance, has an inclination of 2.2 degrees, and an eccentricity of 6%.

The ones known as Scattered Disk Objects, and the Plutinos tend to have eccentric, inclined orbits (these latest discoveries are all SDOs).

Sedna appears to be in a class by itself, orbit wise. Some are referring to it as a "detached" TNO.

See Dave Jewett&#39;s page (http://www.ifa.hawaii.edu/faculty/jewitt/kb-nonframe.html) for more details. Or the list of all TNOs found here (http://cfa-www.harvard.edu/cfa/ps/lists/TNOs.html).

There are some interesting patterns in this data. The 2:3 resonance with Neptune, at about 39AU is chock full of objects (the Plutinos). But the 1:2 resonance at about 50 AU is empty, and the only things farther out are SDOs.

But when you look into the details of the swarm of objects out there, it becomes clearer and clearer that Pluto is nothing more than one of the bigger members of a large family.

rocketblair
2005-Aug-11, 12:26 AM
The term TNO obviously won&#39;t work for similar objects in other solar systems, so a more generic term will be needed for them, but calling the rocky and gas bodies of other systems planets shouldn&#39;t be a problem. If fusion is going on of course it becomes something else, that&#39;s a whole &#39;nuther thing.

TheThorn
2005-Aug-11, 03:50 AM
Actually, all objects around other stars are by definition, "Trans-Neptunian".

;)

cran
2005-Aug-11, 04:17 AM
So, Pluto/Charon, Sedna, Rupert...and the exoplanets become &#39;tinos&#39;? :)

&#39;planets&#39;...meet &#39;tinos&#39; :)

rocketblair
2005-Aug-11, 05:41 AM
TheThorn- If I&#39;m not mistaken, all the planets (exo) that have been detected are all under 6 AU from the stars they orbit, compared to about 30 AU for Neptune around Sol. Calling them all TNO&#39;s makes no sense at all, unless every planet in the universe is a TNO because they all are beyond Neptune. I think the definition of TNO/KBO requires them to orbit our sun, but if I&#39;m wrong, I&#39;ll take my lumps :huh:

Planetwatcher
2005-Aug-11, 07:27 AM
Actually, all objects around other stars are by definition, "Trans-Neptunian".
Could you please supply the source for that definition?
As I have some real problems with it. Namely everything, meaning all other stars, exoplanets, quazars, galaxies, black holes, and more would by that definition be considered "Trans-Neptunian". I really don&#39;t think so.

More realisticly "Trans-Neptunian" would apply to our Solar System and all objects out to the helopause, and perhaps even the Orrt Cloud. But beyond that is considered "intersteller space". It always has been.

[QUOTE] If I&#39;m not mistaken, all the planets (exo) that have been detected are all under 6 AU from the stars they orbit, compared to about 30 AU for Neptune around Sol.

Not quite, but close. The vast majority of exo-planets are with in 6 AU from their parent stars, but in at least a couple of the multi-planet systems, (I don&#39;t know which ones off hand) have an outer giant planet compairible to Neptune in orbital distance.
But that doesn&#39;t make them "Trans-Neptunian" either. However they can be considered the "Trans-Neptunian" equavalant for the system(s) they are in.

But Pluto/Charon, Sedna, Rupert, Quaar, 2005FY9, 2003EL61, Ixion, Varuna,
2004 DW, and 2002 AW197, are all "Trans-Neptunian" objects.
They are also considered KBOs as well.
And now, at least officially Pluto and Rupert are considered PLANETS.

IMHO 2003EL61, Sedna, and 2004 DW, should also be considered planets as well.
All three are nearly the same size, with 2003EL61 the smallest, but it&#39;s also the one with the moon.

We then would have 5 objects very close in size, in the same type of orbits but very different distances from the Sun, made essentually of the same stuff, simular magnitudes, and simular behavior patterns. It will give us a very nice 3rd grouping.

Then we would have
1, the inner terrestrial like rocky planets,
2, the middle gas giant planets,
3, the outer Kupier planets,

What is so hard about that?

Planetwatcher
2005-Aug-11, 07:28 AM
Actually, all objects around other stars are by definition, "Trans-Neptunian".
Could you please supply the source for that definition?
As I have some real problems with it. Namely everything, meaning all other stars, exoplanets, quazars, galaxies, black holes, and more would by that definition be considered "Trans-Neptunian". I really don&#39;t think so.

More realisticly "Trans-Neptunian" would apply to our Solar System and all objects out to the helopause, and perhaps even the Orrt Cloud. But beyond that is considered "intersteller space". It always has been.

If I&#39;m not mistaken, all the planets (exo) that have been detected are all under 6 AU from the stars they orbit, compared to about 30 AU for Neptune around Sol.


Not quite, but close. The vast majority of exo-planets are with in 6 AU from their parent stars, but in at least a couple of the multi-planet systems, (I don&#39;t know which ones off hand) have an outer giant planet compairible to Neptune in orbital distance.
But that doesn&#39;t make them "Trans-Neptunian" either. However they can be considered the "Trans-Neptunian" equavalant for the system(s) they are in.

But Pluto/Charon, Sedna, Rupert, Quaar, 2005FY9, 2003EL61, Ixion, Varuna,
2004 DW, and 2002 AW197, are all "Trans-Neptunian" objects.
They are also considered KBOs as well.
And now, at least officially Pluto and Rupert are considered PLANETS.

IMHO 2003EL61, Sedna, and 2004 DW, should also be considered planets as well.
All three are nearly the same size, with 2003EL61 the smallest, but it&#39;s also the one with the moon.

We then would have 5 objects very close in size, in the same type of orbits but very different distances from the Sun, made essentually of the same stuff, simular magnitudes, and simular behavior patterns. It will give us a very nice 3rd grouping.

Then we would have
1, the inner terrestrial like rocky planets,
2, the middle gas giant planets,
3, the outer Kupier planets,

What is so hard about that?

cran
2005-Aug-11, 07:49 AM
you don&#39;t like &#39;tinos&#39; for Rupert et al? :(

rahuldandekar
2005-Aug-11, 02:56 PM
Sorry about the mistake, Thorn. Thanks for correcting me. :) Actually, I thought that since most of the hyped KBOs have eccentric orbits, almost all of them have. But yes, it&#39;s pretty clear that Pluto and Rupert are large KBOs.

&#39;Tino&#39;s, Cran? It seems good... :)

John L
2005-Aug-11, 03:08 PM
John&#39;s Map of the Solar System

The Sun

Terrestrial Planets:
Mercury
Venus
Earth
Mars

Inner Minor Planets and Asteroid Belts:
Ceres
Vesta
Pallas
Juno

Gas and Ice Giants:
Jupiter
Saturn
Uranus
Neptune

Outer Minor Planets and Edgeworth-Kuiper Belts:
Rupert
Pluto
Quaoar
Varuna
Ixion
Orcus
Sedna
etc, etc, etc...

TheThorn
2005-Aug-11, 03:19 PM
Originally posted by rocketblair@Aug 11 2005, 05:41 AM
TheThorn- If I&#39;m not mistaken, all the planets (exo) that have been detected are all under 6 AU from the stars they orbit, compared to about 30 AU for Neptune around Sol. Calling them all TNO&#39;s makes no sense at all, unless every planet in the universe is a TNO because they all are beyond Neptune. I think the definition of TNO/KBO requires them to orbit our sun, but if I&#39;m wrong, I&#39;ll take my lumps :huh:

I was making a joke, Rock. The ;) should have been a giveaway.

Definition: Trans = beyond. Neptune = the 8th planet in our solar system, located about 30 AU from the sun.

So of course exoplanets are all "trans Neptune", they&#39;re light years away&#33;

Obviously we need another word for small objects distant from their host star if we&#39;re going to start talking about stars other than our own. Unless we have some reason to believe that every solar system has a last planet named Neptune. ;)

John L
2005-Aug-11, 04:28 PM
Mike Brown has made a few updates to his website. (http://www.gps.caltech.edu/%7Embrown/planetlila/index.html#name) The first is more information about the naming of the planet and the debate over whether it is a planet and its name. The kicker is that until the IAU decides how to classify Rupert they will not make a decision on its name...


We have recently discussed the status of the object and of the name with members of the IAU who decide such things. As far as we can determine several activities are taking place:

A special committee of the International Astronomical Union (IAU)is trying to decide precisely what to classify this as.

Another committee of the IAU which vets names for asteroids and Kuiper belt objects is mulling over the name that we suggested upon discovery.
Yet another committee of the IAU which approves names for features on major planets and satellites has suggested that* if the object is declared a major planet the naming falls strictly to them, and they have suggested that the name should continue the Greco-Roman tradition of the previous planets. We have a couple of interesting choices in mind in that case.

It appears that with the dead* month of August rolling around no one will be making decision anytime soon, though the IAU has recently made an offical pronouncement (http://www.iau.org/IAU/FAQ/2003_UB313.html).

The second is that the failure of Spitzer to see Rupert was because it was pointing in the wrong direction. The guys at Spitzer figured it out and have scheduled time for new images to be taken by the end of this month. They are also going to get a little Hubble time and on another infrared telescope to try to nail down the size of Rupert.

Lainie121
2005-Aug-11, 04:30 PM
I am removing the link. Please review Rule 6 (http://www.universetoday.com/forum/index.php?showtopic=1134)

How do you feel about the contraversey
about the so-called 10th Planet? :rolleyes: [COLOR=blue]

StarLab
2005-Aug-11, 05:22 PM
This has been discussed in previous threads already, Lainie. I&#39;m sure one of the mods will join this string with one of those threads.


Though just for the record, I&#39;m in agreement with the general interpretation - that this object should remain a KBO, but Pluto should be kept with planet status for Old Time&#39;s Sake - y&#39;know, tradition.

John L
2005-Aug-11, 07:05 PM
IS that the general concensus, Starlab? I don&#39;t think so&#33; Maybe you should read the thread on Rupert a little more closely. :P

StarLab
2005-Aug-11, 07:24 PM
Tee-hee. <_< :P :rolleyes:

rocketblair
2005-Aug-11, 08:55 PM
Originally posted by TheThorn@Aug 11 2005, 03:50 AM
Actually, all objects around other stars are by definition, "Trans-Neptunian".

;)
You got me on that one, I didn&#39;t notice the smiley all by itself on the last line. :)

John L- What if an outer minor planet is found that is bigger than mercury?
that means minor can be bigger than terrestrial. This is why I don&#39;t like modifying planet. you have to backtrack or revamp everytime a new exception is discovered.

John L
2005-Aug-11, 09:25 PM
Minor Planets, by my system, share their orbits with other minor planets of small bodies. Everything in the Asteroid Belt that is big and round is a minor planet, and the rest are asteroids. Everything in the Edgeworth-Kuiper Belt that is big and round is a minor planet, and the rest are EKBO&#39;s.

Duane
2005-Aug-11, 09:42 PM
I have merged these topics.

rocketblair
2005-Aug-12, 12:20 AM
Originally posted by John L@Aug 11 2005, 09:25 PM
Everything in the Edgeworth-Kuiper Belt that is big and round is a minor planet, and the rest are EKBO&#39;s.
John L- Let me rephrase the question. If a HUGE and round object is found in the EK belt, larger than planet Mercury, does it make scientific sense to describe it with the term Minor planet? Remember, minor used in this way is an adjective which means inferior in number, size or scope. Of course this assumes an obect that size is discovered.

TheThorn
2005-Aug-12, 01:13 AM
An interesting question, Rocket.

I&#39;d say something the size of Mercury in the orbit Pluto is in (or Rupert) would be a minor planet, assuming it&#39;s composition is similar to the other objects in that area.

If Rupert had Mercury&#39;s diameter, it would have a mass of about 0.1 x 10^24 kg, about ten times Pluto&#39;s mass, but only one thousandth of Uranus&#39; mass. So which is it more like, Uranus, or Pluto?

It&#39;s not at all like a terrestrial planet, so those comparisons are meaningless.

Indeed, an icy Earth sized object in the Kuiper Belt (if one existed) would be a minor planet. The fact that none exist, IMHO, has something to do with the way these things form.

Duane
2005-Aug-12, 01:40 AM
Originally posted by TheThorn@Aug 11 2005, 06:13 PM
Indeed, an icy Earth sized object in the Kuiper Belt (if one existed) would be a minor planet. The fact that none exist, IMHO, has something to do with the way these things form.
None is a strong word in this discussion Thorn. That we haven&#39;t seen one "yet" does not necessarily imply that there aren&#39;t any. ;)

Are you serious in suggesting an Earth-massed object in the Kuiper Belt or Oort cloud shouldn&#39;t be considered a planet? I guess it really depends on your definition of planet.

Co&#39;mon IAU lets get a definition already&#33;&#33;

cran
2005-Aug-12, 02:20 AM
Originally posted by TheThorn@Aug 11 2005, 11:19 PM
Obviously we need another word for small objects distant from their host star if we&#39;re going to start talking about stars other than our own. Unless we have some reason to believe that every solar system has a last planet named Neptune. ;)
Alright, hands up all you &#39;Neptunes&#39; out there&#33; :)

rocketblair
2005-Aug-12, 02:45 AM
Originally posted by TheThorn@Aug 12 2005, 01:13 AM


I&#39;d say something the size of Mercury in the orbit Pluto is in (or Rupert) would be a minor planet, assuming it&#39;s composition is similar to the other objects in that area.

If Rupert had Mercury&#39;s diameter, it would have a mass of about 0.1 x 10^24 kg, about ten times Pluto&#39;s mass, but only one thousandth of Uranus&#39; mass. So which is it more like, Uranus, or Pluto?


Your definition of minor planet differs from John L&#39;s, which includes the four largest asteroids which would differ in composition from an object larger than Mercury around Rupert&#39;s orbit. By the way, I found several good images of them, and only Ceres is close to round.

I would say Rupert is much more like Pluto than Uranus, which is why I have a problem with it being called any kind of planet. To me it seems ALL the objects past Neptune, regardless of size should be classified at least for now as TNO&#39;s or KBO&#39;s until we can study the bodies around other stars with greater detail. The system I concur with goes like this

Planets: Mercury through Neptune (Rocky and Gas bodies like these of other systems would also be planets, and the mention of the stars they orbit would help in describing their location and other details

Asteroids: No change needed, they come in many sizes, shapes, and composition. Sub classes are already in place for those who wish to study them, but the general classification of these bodies is fine the way it is. Other systems may have multiple Asteroid belts, or no belt at all but we could still call them Asteroids.

Ort Cloud- No Opinion except maybe OCO for Ort Cloud Object (fancy, huh? :D )

TNO/KBO&#39;s: Rupert is the King for now, but for how long? These bodies also come in various sizes, they belong in a seperate group for obvious reasons, and why confuse the issue by calling them any kind of planet. We do need to hang on to SOME historical part of what we have known that will not be completely blown away by the awesome discoveries were are bound to make in the not too distant future. Ok, had my say... JMHO as always :)

TheThorn
2005-Aug-12, 04:59 PM
Originally posted by Duane+Aug 12 2005, 01:40 AM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Duane @ Aug 12 2005, 01:40 AM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-TheThorn@Aug 11 2005, 06:13 PM
Indeed, an icy Earth sized object in the Kuiper Belt (if one existed) would be a minor planet. The fact that none exist, IMHO, has something to do with the way these things form.
None is a strong word in this discussion Thorn. That we haven&#39;t seen one "yet" does not necessarily imply that there aren&#39;t any. ;)

Are you serious in suggesting an Earth-massed object in the Kuiper Belt or Oort cloud shouldn&#39;t be considered a planet? I guess it really depends on your definition of planet.

Co&#39;mon IAU lets get a definition already&#33;&#33; [/b][/quote]
I think "none" is pretty well demonstrated, Duane. If there were an Earth sized object in the Kuiper Belt (i.e. 30-50 AU from the sun) we would have seen it by now, without any question. That&#39;s demonstrated by the fact that the surveys are picking up much smaller objects, much farther out, by the bucketful.

OTOH, it is possible that there might be an Earth sized object that we have missed in the Scattered Disk, or the Oort Cloud, (i.e. farther out than the Kuiper Belt) but, since all those objects originated in the Kuiper Belt (or farther in, in the area currently inhabited by Neptune, Uranus, and co.) I think we&#39;ll probably find that their sizes match what we see in the Kuiper Belt - i.e. the upper limit is a couple of orders of magnitude smaller than the earth.

And I may have overstepped a touch, saying that such an object (if it existed) would not be a planet. It would be such an anomaly that it would land pretty close to the line.

There&#39;s a huge gap between Mercury and Ceres, as I pointed out above, so there&#39;s no problem telling a major terrestrial from a minor terrestrial. And there&#39;s a huge gap between Uranus and Rupert, so there&#39;s no problem telling a major icy from a minor icy (or whatever name you wish to use for the outer objects) either. An Earth sized icy object would fall on the minor side, but close enough to the middle of the gap to be questionable. But this is all academic, because it appears quite unlikely that such an object exists.

Planetwatcher
2005-Aug-13, 08:37 AM
I like John&#39;s map. By chance is Orcus 2004 DW?

rocketblair
2005-Aug-13, 10:38 PM
90482 Orcus was 2004 DW.

Discovery Date Feb 17, 2004
Images of it have been found back to 1951

Co-discoverer Chad Trujillo estimates it to be ~1600 km,
slightly smaller than Sedna ~1800

Planetwatcher
2005-Aug-14, 11:35 PM
90482 Orcus was 2004 DW.

Discovery Date Feb 17, 2004
Images of it have been found back to 1951

Co-discoverer Chad Trujillo estimates it to be ~1600 km,
slightly smaller than Sedna ~1800
That is what I thought. Now if only I can remember it.

rocketblair
2005-Aug-15, 01:51 AM
Originally posted by Planetwatcher@Aug 14 2005, 11:35 PM
Now if only I can remember it.
One way to remember would be to think of Orcas, the (D)olphin (W)hale. :)

John L
2005-Aug-15, 06:42 PM
We won&#39;t find any big planets in the Edgeworth-Kuiper Belt. Why can I say that definitively? Because a BIG Planet of Earth size or bigger would have swept up or ejected all of the other objects in the belts. Although Jupiter has a small group of trojans, it has otherwise swept its orbit clean. The same with the other "planets." That is why I think there may be something bigger than what we&#39;ve been seeing out past 100AU. The EK Belts cut off out there and I see that as the best sign that there is something sweeping up that orbital space.

So regardless of how big an object we find in the EK Belt it will still be small and too small for most people to be anything more than a minor planet.

rocketblair
2005-Aug-16, 01:33 AM
Originally posted by John L@Aug 15 2005, 06:42 PM
We won&#39;t find any big planets in the Edgeworth-Kuiper Belt.

So regardless of how big an object we find in the EK Belt it will still be small and too small for most people to be anything more than a minor planet.
John L- My question (for the 3rd time) concerns a HYPOTHETCAL object, a little larger than MERCURY, not an EARTH or bigger object. Why Mercury? Because it is the smallest MAJOR Planet that is not in danger of being demoted like Pluto is. I think it&#39;s quite possible one or more may be found, as surveys continue to look in places for these dim objects where they not expected to be. I read somewhere that only 15% of the sky had been studied for these objects. Many Astronomers think there may be Earth sized obects out there, sorry, I can&#39;t quote them but I&#39;m sure you have read it too.

I just have a hard time with the word "minor" used to classify a new object that would be larger than a major, regular, terrestrial, or just good old fashioned Planet, whatever the preference. Again, this is all hypothectical, I&#39;m just looking ahead to see possible problems with classification.

John L
2005-Aug-16, 06:54 PM
As I said, Rocketblair, I don&#39;t think we will, not in the Kuiper Belt anyway. But, to answer your question, the IAU is working on an official definition that will include an absolute minimum for major planet status. Anything smaller will be a minor planet, asteroid, or comet, and everything bigger will be a planet up to the brown dwarf minimum.

rocketblair
2005-Aug-17, 03:34 AM
John L- OK, I give up. The IAU&#39;s minimum size for major planethood won&#39;t be greater than Mercury, but It could be smaller than Pluto if they want to keep it as a major planet. In the latter case it wouldn&#39;t jive with your "map of the solar system" with "outer MINOR planets" Pluto, Rupert, and my hypothetical object which would also be "big and round" and in the EK belt.

Whatever :rolleyes:

John L
2005-Aug-17, 02:19 PM
My map was assuming that Pluto will be demoted. My idea was, Pluto is not a major planet, but its not just another KBO, and the same could be said of Orcus, Ixion, Varuna, Quaoar, and Rupert. Furthermore, if we go by that then Ceres, and some of the biggest asteroids should get a slightly higher classification, too. therefore, we have the eight planets (4 terrestrial, 2 gas giants, and 2 ice giants) with the belts (the Asteroid belts and Kuiper belts) and the minor planets orbiting within those belts.

As I was trying to say, once a planet gets up to Major Planet size, they tend to sweep their orbit clean so a major planet would not share its orbit with lots of other little objects. A minor planet is too small to sweep its orbit clear and therefore will share it with lots of little objects

cran
2005-Aug-17, 03:39 PM
that could work... :unsure: