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Fraser
2004-Mar-15, 06:05 PM
SUMMARY: A new object has been discovered in the Solar System; it's nearly as large as Pluto, but 13 billion kilometres away. Tentatively named Sedna, the Inuit goddess of the Sea, it's approximately 1,700 km in diameter, which makes it the largest Solar System object found since Pluto was located in 1930. Sedna is located in the Kuiper Belt, and follows a highly ecliptic orbit that takes 10,500 years to complete. The object was first discovered using the Gemini Observatory in Hawaii, and then confirmed with several other instruments, including the Spitzer Space Telescope.

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

zrice03
2004-Mar-15, 07:56 PM
This is really cool. Maybe there's an object bigger than Pluto lurking around out there?

Ithaca
2004-Mar-15, 10:35 PM
lots of scientists do think so, for statistical reasons

Tiny
2004-Mar-15, 11:21 PM
:lol: finally the size of our solar system has been increase to ~87 AU...? I bet there's an argument out there, which arguing about: Do we count that as the 10th planet? :lol:

don jennings
2004-Mar-15, 11:35 PM
One thing occured to me, Sedna (Andes spelled backwards if you hadn't already noticed), having a 10,000 year orbit that goes out over almost to the 1000 AU at max distance means it has repeatedly gone thru the heliopause/intersteller boundry over 300,000 times if it has been around since the early days of the solar system. So could the surface have been modified by repeated passages thru this region of space? For instance there are many kinds of charged particles, X-rays. gamma rays, chaotic magnetic fields, etc that the surface may contain traces of that passage. That may help explain puzzling data from Sedna.

jonfr
2004-Mar-16, 01:19 AM
I think it's old, really old...

zephyr46
2004-Mar-16, 03:14 AM
My first thought about Sedna was that it sounded like the first Oort Cloud object, then I saw this ;

http://images.spaceref.com/news/2004/ssc2004-05d_medium.jpg

SpaceRef.com story (http://www.spaceref.com/news/viewpr.html?pid=13841)

Meanwhile over at Caltec Sedna (http://www.gps.caltech.edu/~mbrown/sedna/), that same question is being asked, the compromise position being 'inner Oort Cloud Object'.

joshua page
2004-Mar-16, 04:26 AM
Sedna is the end. This planetoid is going to hit the earth and cause so much chaos...

Faulkner
2004-Mar-16, 04:33 AM
Crazy, dude! :P

Tiny
2004-Mar-16, 05:13 AM
I believe soon, they gonna run out of the Rome god or goddess name... :lol:

david Gray
2004-Mar-16, 05:32 AM
Originally posted by zrice03@Mar 15 2004, 07:56 PM
This is really cool. Maybe there's an object bigger than Pluto lurking around out there?
How can Sedna be so small in our solor sytem that is is the reddest object after Mars? :o

NotScientific
2004-Mar-16, 02:39 PM
BTW what's the Oort Cloud??

Spacemad
2004-Mar-16, 03:33 PM
Originally posted by fraser@Mar 15 2004, 06:05 PM
The object was first discovered using the Gemini Observatory in Hawaii, and then confirmed with several other instruments, including the Spitzer Space Telescope.


:) Apparently it was first discovered on November 14th last year. So why has NASA waited 4 months to announce the discovery to the general public? Were they afraid there was a mistake in the finding? Were 4 months investigation really necessary before making the announcement?

Nevertheless, itīs still an important find! Itīs the first major discovery in our Solar System since the discovery of Pluto! It seems that it is too close to the Sun to really be counted as a Oort Cloud object but too far away to be classed as a Kuiper Belt object - so they called it an "Inner Oort Cloud " object! :unsure:

Gorothbalion
2004-Mar-16, 03:51 PM
Hmmm.

If it took them this long to find this object (planetoid), it may be a while before we know for sure that it is the last planet/planetoid out there. I speculate that there are many more of these objects out there. Soon, I think that we will start hereing more about them.

First of, they need to get their classifications correct. What is really a planet? How great is a solar-system? Things like these must be classified. I think our solar-system is far greater than 87 Astronomical Units, one day it may be something like 1 parsec, or at least 1 light-year.

They are sending out a probe to the Kuiper Belt, and to Pluto, but it will reach the planet in over ten years if successful. That is a long time to wait. One thing is for certain, there is a lot more out there than we originally thought, and a lot more to discover as well.

antoniseb
2004-Mar-16, 04:01 PM
Originally posted by NotScientific@Mar 16 2004, 02:39 PM
BTW what's the Oort Cloud??
Hi NotScientific, welcome to the forum.

The Oort 'cloud' is roughly ten trillion comets that were ejected from the inner solar system during the planet forming period [first 100 million years]. The comets have very long periods [millions of years] having their closest approaches to the sun somewhere between the orbits of Jupiter and Neptune for the most part. They spend the vast majority of their time in the outer reaches of the sun's gravity about 10 to 20% of the way to Alpha Centauri, the next nearest star system.

zephyr46
2004-Mar-16, 11:44 PM
BBC News article (http://news.bbc.co.uk/2/hi/science/nature/3514594.stm?from=astrowire.com#graphic) suggesting Sedna may have a moon. Seems to be pretty common out there, Minor Planet & Comet Connections Binary objects list (http://www.hohmanntransfer.com/topics.htm#binary).
It looks like the first Kuiper Belt object discovered may be Binary, so there is a fair chance the Sedna may have a moon as well.
In other news, Quaoar may have some notable surface features (if not a moon).
Can we really call these Binaries moons though ? It certainly scores points for calling them planets if we do.

Guest
2004-Mar-16, 11:53 PM
does anyone know where(if anywhere) that its actualy written down what a planet is and what isnt a planet??? cause if pluto is planet then why cant Charon be a 'sister(or brother)' planet. To the extent of my 8th grade scince(the grade im in) charon aint much smaller than pluto, right???

nerdman20
2004-Mar-16, 11:55 PM
i just registered i was the one that made that comment ^^^^^^^


i made it cause tommorro we are discussing extra terristial life and this new planetoid Sedna and stuff so i figured id start getting more info on the subject an

antoniseb
2004-Mar-17, 12:09 AM
Originally posted by Guest@Mar 16 2004, 11:53 PM
does anyone know where(if anywhere) that its actualy written down what a planet is and what isnt a planet??? cause if pluto is planet then why cant Charon be a 'sister(or brother)' planet. To the extent of my 8th grade scince(the grade im in) charon aint much smaller than pluto, right???
You're not going to like the answer: It isn't written down what is the limit that separates a small planet from a large asteroid [or planetoid], and even if it was, not everyone would agree.

That being said, one factor is that we don't want people to have to memorize hundreds of names of planets. Since we think there might be dozens or maybe hundreds of things like Sedna, eventually, if it were a planet, such memorization would become difficult.

As it is now, you can remember "My Very Educated Mother Just Served Us Nine Pizzas". You can easily change the end to be "Pizza Slices" to include Sedna. But with enough being loose about what's called a planet, you might end up with "My Very Educated Mother Can Just Serve Us Nine Pizzas 'Cause Very Smart Children Need Good Food When They Study, Especially In March And April Because When They Are Hungry Everything Seems So Dark And Dismal That They Just Want To Give Up."

A lot of people think the list of Planets shoud stay an exclusive club, and that we let Pluto in by mistake, but its a mistake we can live with.

John LaCour
2004-Mar-17, 04:46 AM
Originally posted by david Gray+Mar 16 2004, 05:32 AM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (david Gray @ Mar 16 2004, 05:32 AM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-zrice03@Mar 15 2004, 07:56 PM
This is really cool. Maybe there&#39;s an object bigger than Pluto lurking around out there?
How can Sedna be so small in our solor sytem that is is the reddest object after Mars? :o [/b][/quote]
There are two general types of objects known in the outer regions of the solar system. A lot of them seem to be fairly dark objects reflecting only about 6% - 9% of the sunlight that reaches them. Pluto&#39;s moon Charon, as well as many of the largest Kuiper Belt object are in this group. The others are reddish in color and can reflect as much or more than 50% of the sunlight that reaches them. Pluto happens to be in this group&#33; I don&#39;t remember what chemicals cause the reddish color, but there are many objects out there that are similar.

The Outer Solar System
There have been three groups of objects in the Kuiper Belt region until now. They were the Classical KBO&#39;s that orbit a little further out than Pluto in a fairly circular orbit near the ecliptic, the Scattered KBO&#39;s that orbit a little further out still in highly eliptical orbits sometimes many degrees off the ecpliptic, and the Plutino&#39;s that orbit in basically the same orbit as Pluto in a 3:2 resonance with Neptune. Now there are what some are calling the Inner Oort Cloud. This one seems to orbit from about twice the distance from the sun as Pluto out to 1/10th the distance to the Oort Cloud. The Oort cloud, as said in other posts, is a shell of cometary objects about 1/4 lightyear from the sun.

What is a Planet?
There have been arguements about what is a planet for several hundred years. In the mid-1800&#39;s telescopes had improved and proliferated to the point that the first (and largest) objects in the asteroid belt were discovered. The asteroids Ceres, Pallas, Vesta, and several others were discovered and at first were designated as planets. At one point Jupiter was considered the 10th planet and Saturn the 11th (nothing beyond Saturn had been discovered at that time). Now we find ourselves in the same situation. The brightest member of a group of bodies, Pluto, was discovered in 1930 and was designated a planet before we knew anything about its size. It wasn&#39;t until 40 years later that we discovered exactly how small Pluto was, but it wasn&#39;t for another 25 years before we discovered other large objects sharing its region of space. Now we have found Ixion, Varuna, Quaoar, 2004 DW, and Sedna. So what do we call these objects?

I&#39;ve seen two good definitions for what is a planet. The first is the a "planet" is any object that is spherical due to the force of its own gravity, differentiated (core, mantel, crust), and orbits a star (rather than a planet). The problem with this definition is that not only would Pluto be a planet, but Ceres, Vesta, Pallas, Varuna, Ixion, Quaoar, Sedna, 2004 DW, and possibly thousands of other objects in the dark outer reaches of the solar system would qualify, too. Imagine learning the names of 1,000 planets in grade school science class&#33;

The alternative to this defintion is the same as above plus one additional qualification: the object should not share its orbit with other similar sized objects. With that qualification, none of the asteroids or Kuiper Belt Objects qualify (including Pluto) because they share their orbit with other similarly sized objects. Jupiter and Saturn also share their orbits with small "Trojan" asteroids that preceed and follow each planet at their L4 and L5 Lagrangian points, but since they are no where near as large as a gas giant planet, Jupiter and Saturn still qualify.

So what else is out there
Astronomers have estimated between a few dozen to several hundred more large objects beyond Neptune. They also estimate that Pluto is probably not the biggest with maybe 6 as yet undiscovered worlds larger than Pluto. Beyond that, at an incredible distance of about 1/4 lightyear, is the Oort Cloud. The Oort Cloud is technically in interstellar space, outside of the heliosphere, but is gravitationally bound to our star. At one time there was the Nemesis theory, which theorized that a large gas giant or brown dwarf orbited the sun between the Kuiper Belt and Oort Cloud. Based on some old orbital calculations, it was believed that unusual motions in Neptune&#39;s orbit could only be explained by a large body somewhere out there. Currently, though, it has been shown that some of the older observations included in Neptune&#39;s orbital calculations could not be relied on, and, after their exclusion, the supposed Nemesis disappeared from the equations.

John LaCour
2004-Mar-17, 04:54 AM
Originally posted by Guest@Mar 16 2004, 11:53 PM
does anyone know where(if anywhere) that its actualy written down what a planet is and what isnt a planet??? cause if pluto is planet then why cant Charon be a &#39;sister(or brother)&#39; planet. To the extent of my 8th grade scince(the grade im in) charon aint much smaller than pluto, right???
Pluto and Charon are considered by some to be a "dounle planet." The reason is the doubly resonant orbit that they share. Because of the similarity in size, the center of gravity between the two is actually outside of Pluto in the space between them, the point about which they both orbit. Just like our Moon, Charon&#39;s day is the same length as the time it takes it to orbit Pluto (or the mutual center of gravity) so that the same side of Charon always faces Pluto - just like our Moon. But Pluto&#39;s day is also the same amount of time as a Charon "month" so that Charon not only shows the same face to Pluto, it also stays over the exact same point of Pluto as it orbits. Each have the same length of day and period of orbit around each other is what they call them doubly resonant. This creates an interesting effect. Because Charon is always over the same place on Pluto, from one side of Pluto Charon will always be high overhead while from the other side of Pluto you would never even know Pluto had a moon.

Peter Canuck
2004-Mar-18, 10:19 PM
Does anyone recall us having this discussion about a month ago.

Feb 20th or 21st, we had a posting and discussion about a new Kuiper Belt object called 2004DW or something like that.
I am going to assume this is a different Kuiper Belt object and not the same one.

I also recall then the forum posters saying their could be many more larger objects in the Kuiper belt waiting for discovery. Guess we were all right. The fact this one was found 4 months ago doesn&#39;t seem to change what we talked of then.

That led to the &#39;Whats a planet?&#39; discussion and if I recall the words correctly, it had to do with maintaining orbit, mass, and alot of other stuff.

Go back in the discussions and see if you can find it. I think it was Feb 20 or 21.

antoniseb
2004-Mar-18, 11:20 PM
Originally posted by Peter Canuck@Mar 18 2004, 10:19 PM
... we had a posting and discussion about a new Kuiper Belt object called 2004DW or something like that. I am going to assume this is a different Kuiper Belt object and not the same one.
2004DW is a different KBO, but it is mentioned in the recent paper that also discusses Sedna as evidence that a sun sized star passed through the solar system with a closest approach of about 800AU, about 100 Myears after the planet forming period began.

2004DW has aphelion and perihelion distances about half that of Sedna.

Nick4
2004-Mar-20, 05:23 PM
Thats cool another one. So if you lived on that planet you would be very old seeing is that it takes 10,500 years for one year on that planet WOW.

damienpaul
2004-Mar-20, 11:45 PM
What is the size of 2004DW? does it also have a &#39;red&#39; surface?

Tiny
2004-Mar-21, 03:07 AM
I believe this website can answer your question :lol: :
http://www.gps.caltech.edu/~chad/2004dw/

Hope this help

Cheers

Duane
2004-Mar-22, 07:00 PM
Heh, like your new sig Tiny :)