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Reacher
2003-Apr-15, 03:53 PM
A while ago there was lots of talk on the boards about Pluto being defined as a KBO. whats the latest? Has it happened?

ToSeek
2003-Apr-15, 04:16 PM
I think Pluto right now has dual citizenship: It is definitely a KBO, but the IAU is maintaining its status as a planet as well. But, as the article below suggests, if we ever find a KBO larger than Pluto, things could get interesting.

NASA article on topic (http://science.nasa.gov/newhome/headlines/ast17feb99_1.htm)

tracer
2003-Apr-16, 12:20 AM
From the Internet Stellar Database entry on the Sol system (http://www.stellar-database.com/Scripts/search_star.exe?Name=Sol):

The "8" in the Detected Planets entry is not an error. Pluto is not a "planet," but a huge, close-orbiting, low-eccentricity Kuiper Belt object. With a big moon. Of course, some die-hards out there still insist that it really is a planet, more for sentimental reasons than anything else. They're welcome to live in their little fantasy world. Neener neener.

kilopi
2003-Apr-16, 01:51 AM
I think Pluto right now has dual citizenship: It is definitely a KBO, but the IAU is maintaining its status as a planet as well. But, as the article below suggests, if we ever find a KBO larger than Pluto, things could get interesting.

NASA article on topic (http://science.nasa.gov/newhome/headlines/ast17feb99_1.htm)
Hey, now. How many times are we going to do this?

According to that link, Pluto has only one status at the present time: planet.

RickNZ
2003-Apr-16, 04:00 AM
The copernbicus model wasnt dropped over night nor will the mis naming of pluto.
Lets just say if pulto was just discovered today you and I both know how it would be labled.

kilopi
2003-Apr-16, 05:51 AM
Well, if Jupiter and the gas giants were discovered today, they wouldn't be called a planet either. They'd be compact nebula or something. :)

tracer
2003-Apr-18, 12:33 AM
Compact nebula? Nah. Low-mass, low-eccentricity, cool brown dwarfs! ;)

nebularain
2003-Apr-19, 01:57 AM
Well, well, well. I was looking up some info on space probes, and found this one from NASA (http://solarsystem.nasa.gov/missions/profile.cfm?Sort=Planet&Object=Pluto) on the future mission to Pluto. It says, and I quote:

"In recent years, scientists have recognized that Pluto, is actually a Kuiper belt Object, . . . ."

:D :P :lol:

kilopi
2003-Apr-19, 03:36 PM
Well, well, well. I was looking up some info on space probes, and found this one from NASA (http://solarsystem.nasa.gov/missions/profile.cfm?Sort=Planet&Object=Pluto) on the future mission to Pluto. It says, and I quote:

"In recent years, scientists have recognized that Pluto, is actually a Kuiper belt Object, . . . ."
Obviously written by a committee. The first sentence says "Pluto, the smallest planet, is the only planet not yet visited by a spacecraft."

Somebody there is wrong, right? I wonder who?

Remember, "planet" is just a designation.

This Is Your Brain On FOX
2003-Apr-20, 04:56 AM
I really don't understand this entire Pluto\KBO argument.

Pluto is a pretty substantial distance from the Kuiper belt, at times Neptune is closer to the Kuiper belt than Pluto is, I don't hear anyone suggesting that Neptune is a KBO.

Kaptain K
2003-Apr-20, 10:52 AM
I really don't understand this entire Pluto\KBO argument.

Pluto is a pretty substantial distance from the Kuiper belt, at times Neptune is closer to the Kuiper belt than Pluto is, I don't hear anyone suggesting that Neptune is a KBO.
Neptune is the fifth largest object in the solar system. Pluto is smaller than several moons (including our own) and only slightly larger than some of the (so far discovered) KBO's.

kilopi
2003-Apr-20, 04:47 PM
Pluto is smaller than several moons (including our own) and only slightly larger than some of the (so far discovered) KBO's.
Slightly being almost one order of magnitude, right?

aurorae
2003-Apr-20, 06:13 PM
Slightly being almost one order of magnitude, right?

An "order of magnitude", IIRC, is 10x. Certainly the diameters are not 10x different. I've forgotten the formula for the volume of a sphere...

Quaoar probably has a diameter of 1300km (and a nearly circular orbit).

http://www.solarviews.com/eng/quaoar.htm

There are two other KBO's with diameters of about 900km.

Pluto's diameter is 2274km.

http://www.solarviews.com/eng/pluto.htm#stats

Just as Ceres was the first asteroid detected, and it turned out to be the largerst, it may very well be that Pluto is the largest KBO.

David Hall
2003-Apr-20, 06:28 PM
I really don't understand this entire Pluto\KBO argument.

Pluto is a pretty substantial distance from the Kuiper belt, at times Neptune is closer to the Kuiper belt than Pluto is, I don't hear anyone suggesting that Neptune is a KBO.

??? Pluto is smack-dab in the middle of the Kuiper belt. At about 40AU, it falls neatly within the 30-100AU belt. (Data from The Nine Planets (http://seds.lpl.arizona.edu/nineplanets/nineplanets/kboc.html))

In addition, the composition appears to be similar to KBO's, and the size is only about double that of the largest known KBO. There's a lot we still don't know though, such as the exact composition and why it has such a large moon, but the arguments for KBO status are pretty strong. Not decisive yet, IMO, but strong.

Neptune of course could never be a KBO because it is very different from them in every aspect. It's a large gas/ice giant with it's own system of rings and moons. It's also closer to the Sun. In fact, an alternate name for the Kuiper Belt is "Trans-Neptunian Object", that is objects outside of the orbit of Neptune, so the orbit of Neptune itself is kind of a defining point for KBO's. Objects between Jupiter and Neptune are called Centaurs, and generally have unstable orbits, as stated by TNP (http://seds.lpl.arizona.edu/nineplanets/nineplanets/asteroids.html).

As for the odd 20 year period when Pluto crosses inside Neptune's orbit, that's not a big problem. Many objects have eccentric orbits, and the fact that Pluto goes outside of the main KB range occasionally doesn't exclude it from the KBO group. It's the average orbit and other similarities that make an object part of a certain group, not the exceptions

kilopi
2003-Apr-20, 07:15 PM
Slightly being almost one order of magnitude, right?

An "order of magnitude", IIRC, is 10x. Certainly the diameters are not 10x different. I've forgotten the formula for the volume of a sphere....
That's no excuse...you have the entire internet at your fingertips, all that seconds away. :)

It's the mass that's important.

aurorae
2003-Apr-21, 12:06 AM
It's the mass that's important.

Is there a web site that says the Pluto's mass is 10 times more than any other KBO? I didn't find one.

Regarding Pluto's uniqueness, I suspect that, compositionally, Pluto is very close to Triton.

It would be interesting to learn more about Chiron, and whether it was formed next to Pluto or was captured, and, if captured, how that could have happened. Maybe a mission to Pluto could reveal enough to give clues to the answers.

David Hall
2003-Apr-21, 03:17 AM
It would be interesting to learn more about Chiron, and whether it was formed next to Pluto or was captured...

Careful. That's Charon. Chiron is one of the Centaur bodies.

(I used to get them confused too, so don't feel bad.)

kilopi
2003-Apr-21, 03:36 AM
It's the mass that's important.

Is there a web site that says the Pluto's mass is 10 times more than any other KBO? I didn't find one.

Regarding Pluto's uniqueness, I suspect that, compositionally, Pluto is very close to Triton.
They do have nearly the same density, but that density is more than twice that of water, whereas comets are often less than water. I think SL was around .6 g/cc. And of course Saturn itself has a density less than water.

Quaoar isn't much more than 10% the mass of Pluto. I don't think they actually know what the mass of Quaoar is, which may explain why you didn't find a reference. Pluto's mass seems to be well-documented. However, Quaoar's radius is about 1250km, measured with radio scopes and the Hubble, so even if it were as dense as Pluto (which it may not be), it would still be only (1250/2274)^3, or 16% of the mass of Pluto. All the other KBOs are some smaller I believe.

CalabashCorolla
2003-Apr-22, 01:03 AM
I heard that the Rose Center for Earth & Space in NYC (the space museum that resembles an enormous glass Rubik's Cube) omitted Pluto from its model of the planets of the solar system, which apparently caused a huge stir among astronomers....has anyone been there and seen this display? Do they mention Pluto at all?

kilopi
2003-Apr-22, 01:15 AM
That omission by the Rose Center a couple years ago pretty much jumpstarted the Pluto debate. They do mention Pluto (http://wildcat.arizona.edu/papers/94/87/01_95_m.html).

SollyLama
2003-Apr-22, 09:13 PM
This points out a huge failure in the defining of celestial objects.
They can't call Pluto a planet because there is no definition of planet. It's obviously a KBO, and as our detection capailites grow, we're going to run into more objects that may outsize Pluto. Then what?
Is Charon a moon? Moons generally orbit a larger object. But Pluto and Charon orbit a common point between them.
Somewhere else in the galaxy we might call Jupiter a brown dwarf.
There are moons in the solar system bigger than 'planet' Pluto.
Space.com recently had an interesting article on the topic and how there is very few hard and fast definitions for objects. They don't know what criteria to apply.
At some point the astronomical community are going to have to apply a lower limit for what we want to call a moon. Jupiter's collection of rocks is growing as our detection equipment gets better and eventually we're going to be calling pebbles 'moons'.
One more issue:
Under the criteria of being in orbit around a larger object, shouldn't every pebble in Saturn's rings be considered an individual 'moon'? Better break out the big book of names.......
So what criteria do you learned folk think should be applied?

Reacher
2003-Apr-22, 10:20 PM
You cant call anything a planet unless there's a definition. I mean, without definithion, what've we got? bunch of rocks, couple brown dwarfs, a few belts, all circling a fire.

I dislike the name Quaoar. Cant we call it something cool, inspiring, majestic, pronouncable?

Are there ant celestial objects called Mjolnir? Now, thats a cool name

David Hall
2003-Apr-22, 10:43 PM
I don't know. Quaoar has kind of grown on me. Hard to remember how to spell though.

There doesn't seem to be a Mjolnir asteroid (http://cfa-www.harvard.edu/iau/lists/MPNames.html), but there is a Mjolnir (http://antwrp.gsfc.nasa.gov/apod/ap990610.html) impact crater.

Glom
2003-Apr-22, 11:02 PM
Are there ant celestial objects called Mjolnir? Now, thats a cool name

Wasn't that the Tok'ra that took Carter as a host in 'In the Line of Duty'?

kilopi
2003-Apr-23, 10:07 AM
This points out a huge failure in the defining of celestial objects.
All good points. We have discussed it some before (http://www.badastronomy.com/phpBB/viewtopic.php?p=34053&highlight=ceres#34053) in other threads, and the professionals are hard at work at it too, now that it has received a lot of publicity. :)


Is Charon a moon? Moons generally orbit a larger object. But Pluto and Charon orbit a common point between them.
Somewhere else in the galaxy we might call Jupiter a brown dwarf.
I'd just like to point out here that in that sense Jupiter doesn't orbit the Sun either.

QuagmaPhage
2003-Apr-23, 10:24 AM
I hope that astronomers will soon discover 1 or 2 Pluto sized KBO's which will be classified as planets. Then watch the astrologers try to come up with ideas for what impact the new planets will have on horoscopes. And watch their feeble explanations when more Pluto sized objects are discovered and IAU declassifies them all, including Pluto, as KBO's. :D

dgruss23
2003-Apr-23, 11:12 AM
QuagmaPhage wrote: Then watch the astrologers try to come up with ideas for what impact the new planets will have on horoscopes. And watch their feeble explanations when more Pluto sized objects are discovered and IAU declassifies them all, including Pluto, as KBO's.


Shouldn't the astrologers be able to predict when all that will happen. That would certainly affect them and that's what they do ... right - predict how astronomical events affect human lives.

kilopi
2003-Apr-23, 11:55 AM
Based upon my long years as an astrologer (and my familiarity with the future), I predict...that it won't happen.

Update (23 Apr 2003 12:07 EDT)
I'd just like to point out that as of now, I am still right.

gethen
2003-Apr-23, 02:46 PM
I think Mjolnir is Thor's hammer, isn't it? Cool name.