Another tenth planet

[geni]

This one is seems to be only slighlty smaller than Pluto.

Astronomers have discovered a new world circling the Sun farther away than other planets.
Found in an outer Solar System survey by the recently launched Spitzer Space Telescope, it has been called Sedna after the Inuit goddess of the ocean.

Observations show it is about 2,000 km across, and it may even be larger than Pluto which is 2,250 km across.

http://news.bbc.co.uk/1/hi/sci/tech/3511678.stm

There will be more detials when the date in the US catches up with the date here

[Reginald]

Originally posted by geni
This one is seems to be only slighlty smaller than Pluto.


http://news.bbc.co.uk/1/hi/sci/tech/3511678.stm

There will be more detials when the date in the US catches up with the date here

Well it's still possible it's larger than Pluto. If that's the case then it's a planet (if Pluto is).

[Yahweh]

Any chance we're going to find that planet where all the Mormons go after they die?

[neutrino_cannon]

As long as you define planet as any body that's spherical due to it's own gravity and orbits a sun (I like it because it's objective), then ceres is a planet too.

Of course, Titan Io company are all moons larger than several planets, including IIRC, mercury.

All very confusing.

Also, looking through my books on the subject, the phrase "planet x" has been used many times to describe hypothetical objects to explain irregularities in the orbits of the outermost planets.

[Cecil]

So now we have two or three tenth planets and no eleventh planets?

Someone needs to take kindergarten math again. :D

[geni]

Originally posted by Cecil
So now we have two or three tenth planets and no eleventh planets?

Someone needs to take kindergarten math again. :D

Well of course it could be argued (and I do) that this discovery means that there are only 8 planets.

[El Greco]

Gustav Holst should have composed 2-3 more pieces just in case....

[jj]

Originally posted by geni


Well of course it could be argued (and I do) that this discovery means that there are only 8 planets.

Io you one for that, you can't be Ceres, can you?

It is, however, a good question, what does count as a planet?

The moon would count under the standard used for Pluto, yes, except for the orbit (minor detail)

[geni]

Originally posted by jj
It is, however, a good question, what does count as a planet?

The moon would count under the standard used for Pluto, yes, except for the orbit (minor detail)

The problem with that aproach is that Jubiter's largest moon is bigger than Mecuary.

[jj]

Originally posted by geni


The problem with that aproach is that Jubiter's largest moon is bigger than Mecuary.

Why is that a problem? Either planets can orbit other planets ore they can't. If they can, then they are both planets, otherwise they are both moons. Can a moon be bigger than a planet? Well, good question. If they can't, what is Mercury, besides hot!

As far as all of these trans-pluto objects, do planets have to have close-to-circular orbits, does their orbit have to be "clear" (i.e. not have multiple objects in it, etc), and so on.

I'm not sure what might be Deimos important question, really.

[phildonnia]

What's the big deal whether its a planet or not.

What I'd like to know is, has anyone attempted yet to link the planet to the "Nemesis" hypothesis?

http://www.physics.louisville.edu/nineplanets/hypo.html#nemesis

[kookbreaker]

"LOOK OUT! ITS COMING RIGHT FOR US!"

[Ian Osborne]

And don't forget 'planet' is simply a label we've applied to the phenomenon. Whether a sufficiently-large celestial body which orbits another planet counts as a planet itself is a matter of semantics rather than science.