tenth planet?

from cnn.com

http://www.cnn.com/2004/TECH/space/03/15/distant.object/index.html

Scientists:

Most distant object in solar system found

Monday, March 15, 2004 Posted: 2:37 PM EST (1937 GMT

(CNN) -- Scientists may have discovered the solar system's most distant object, more than three times farther away from Earth than Pluto.

"The sun appears so small from that distance that you could completely block it out with the head of a pin," said Dr. Mike Brown of the California Institute of Technology, who helped in the discovery.

The object -- about 8 billion miles (12.8 billion kilometers) from Earth -- has been given the provisional name of Sedna, after the Inuit goddess who created sea creatures of the Arctic.

Brown and his team of astronomers, using Caltech's Palomar Observatory, found Sedna in November as part of an ongoing three-year outer solar system project. Days later, the high power Spitzer Space Telescope focused on the object.

Initial details indicated Sedna to be made of ice and rock, with temperatures never rising above -400 degrees Fahrenheit (-240 degrees Celsius), according to researchers.

Sedna is likely the largest object to be found circling the sun since the discovery of Pluto in 1930. It is still smaller than the ninth planet, though, with a diameter of more than 1,000 miles (1,700 kilometers).

The finding has sparked debate over what constitutes a planet.

Many astronomers say Pluto, with a diameter of just under 1,500 miles (2,300 kilometers), is too small to be a termed a planet and is just one of many minor objects in the outer reaches of the solar system.

But those who argue Pluto is a planet are likely to push the assertion for Sedna to become the 10th planet in the solar system.

This asks for a debate about what constitutes a planet. Well, what constitutes a planet? I'm rather undecided on this matter and I would like to hear your thoughts.

Humn, what about the asteroid/planet I thought they discovered in orbit around the sun beyond Pluto? Did they forget about that one when counting or is it perhaps the same object?

I think an agreed minimum size should be adopted. It gets silly if we add any natural object in orbit around the sun to the list.

I'm not too bothered about Pluto because it's pretty darn big by the standards of most asteroids but the line has to be drawn somewhere.

But the solar system always needs more planets! We must have MORE!

Why do we even use the world "planet"? Why not just call everything an asteroid, some bigger than others?

[I edited this post out]

Originally posted by WillJ
Why do we even use the world "planet"? Why not just call everything an asteroid, some bigger than others?

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You would call Jupiter an asteroid?

Pluto and Sedna are so small, I don't know what makes them planets. Why aren't they refered to as asteroids?
Could someone with knowledge on this educate me?

Some astronomers already question the fact Pluto is a planet. However, if Sedna is really the 10th planet, then the chosen name sucks. Something like "Juno" or "Janus" was better according to me.

I've mentionned Juno because I consider it's unfair only one of the 8 other planet than earth is named as a Goddess and not as a God.

However, I've also mentionned "Janus" because, as the God of the Doors, it we could consider that planet as a link between our solar system and the outter space.

Sedna, what kind of crap name is that, I say stick to greco-roman.

The object (...) has been given the provisional name of Sedna, after the Inuit goddess who created sea creatures of the Arctic.

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That sounds good to me.
And...Janus? Don't we have enough stupid puns about Uranus?

Pluto got grandfathered in.

Seriously, at the time it was first proposed that something existed, out beyond Neptune, no one yet had any idea that there might be many decent-sized bodies in that region; anything hypothesize to be there was therefore automatically assumed to be a full-fledged planet. It was only later, after Pluto was actually found, that it was realized how extremely eccentric its orbit was and how small it was, and by that time it was already categorized.

Now that it's clear that Pluto is only one of the largest and nearest (maybe the largest, who knows) of many similar bodies out beyond the orbit of Neptune, should it still be considered a planet? Who knows -- take your pick.

(By the way, the previously-discovered body stormbind mentioned was named Quouar or something like that; Sedna is yet another one.)

Ren

Originally posted by Renata
(By the way, the previously-discovered body stormbind mentioned was named Quouar or something like that; Sedna is yet another one.

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We should create an academy in charge of giving names to stars, asteroids, comets and things as such. Seriously, astronomers are really awful at it. Quouar ? Are you serious ? That sounds like coward in french !

The term "planet" is rather abitrary. Thousands of objects circle (or should I say : "ellipsle" ) around the Sun : the ordinary planets, tons of asteroids (many between Mars and Jupiter), many comets, far objects we call TNOs (Trans-Neptunian Objects), and now those really far objects that might come from the Oort Cloud ?...

My personal opinion tells me I consider 8 real planets : Mercury to Neptune. Those 8 objects have a decent size, are rather spherical, have a low orbit eccentricity around the Sun, and have their orbits located in the rather same plan (little angle). As for Pluto, this thingie is rather small, has such an eccentricity (ellipsoidal) that it crosses Neptune's orbit once in a while (happened 1979-1999), and its orbit plan has a large angle compared to the other planets. All of this making Pluto a rather strange planet... And we know it has a rather big (in comparison) companion, called Charon, quite close to Pluto, which is somewhat unusual for a planet. Maybe Pluto came from somewhere else than the close Solar proto-disk...?

Now this thing, Sedna, nice name but no, it's not a planet in my standards. And I don't think there will be a 10th planet (if there even is a 9th one ! ). Nothing prevents you from setting up a new category of objects, though. Asteroid ? no, asteroids aren't spherical and are smaller than that. There is a limit in size above which an object HAS to be spherical (can't remember exactly how much from memory).

This news is cool anyway, just look at its eccentricity, man ! Now at 13 billion kms, but going as far as 130 billion kms !! That's incredibly far away.

If you deny the status of Pluto as a planet (which is something perfectly understandable), I guess we can't do it only because of the size. Indeed, Pluto is bigger than Mercury... it's even bigger than Mars.

Interesting, yet I wonder why it wasnt found earlier.

I just call 'em all worlds!

Originally posted by Marla_Singer
If you deny the status of Pluto as a planet (which is something perfectly understandable), I guess we can't do it only because of the size. Indeed, Pluto is bigger than Mercury... it's even bigger than Mars.

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Pluto's diameter is considerably smaller than both Mercury and Mars (as well as seven satellites in the solar system, our moon included). The only reason it is included as a planet is because it was discovered in 1930, whereas other Kupier Belt objects didn't even start to be discovered until 1992. As it is, it is almost certain that Sedna will not be classified as a planet. I imagine that if a Pluto-sized body is found, there will be more of a debate over whether to declassify Pluto as a planet than to classify that object as one. I do have to wonder though, what if a body the size of Mercury or larger is discovered? The chances of one of those being in the Kupier Belt or inner Oort cloud are fairly good from what I can tell.

Originally posted by CivCube
But the solar system always needs more planets! We must have MORE!

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Why don't we take a trip to Alpha Centauri and bring back some planets, eh?

Originally posted by Marla_Singer
If you deny the status of Pluto as a planet (which is something perfectly understandable), I guess we can't do it only because of the size. Indeed, Pluto is bigger than Mercury... it's even bigger than Mars.

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I believe you confused Pluto and Ganymede, the largest moon in the solar system.