XR4-IT
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The nuts Androsynth
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So the planet debate has heated up again and in fact it looks like we will soon have a new planet definition…
See this http://www.msnbc.msn.com/id/14364833/?GT1=8404
The article describes the new planet definition and gives the names of new planets like Ceres (between Mars and Jupiter) Charon & Pluto as a bi-planet and Xena (2003 UB 313 beyond Pluto)
So what’s your opinions on the “new” planets.
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Lance_Vader
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Why Xena? Why not one of the Roman gods we haven't already used? I mean, it's not like we're going to run out of 'em or anything...
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Arne
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Wha? Their definition exludes any moons so why include Charon?
I'd say there are 8 planets, if it weren't for the fact that Pluto has a moon, which makes it rather planet like... but then again, Xena does also have a moon, doesn't she? Applying digital definitions on analog stuff is tricky business.
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Draxas
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I wonder where I can get a stuffed Cthulu from? 
See that? Reorganizing the solar system makes children cry, and then want to kill you.
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XR4-IT
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I have more on the question: why our moon Luna is not now considered a planet if Charon is now a planet?
Q: Is Pluto a planet?
A: Yes. In fact, Pluto’s large companion named Charon is also large enough and massive enough to satisfy the definition of “planet”. Because Pluto and Charon are gravitationally bound together, they are actually now considered to be a “double planet.”
So that still sounds like a contradiction of the definition.
Q: What is a “double planet”?
A: A pair of objects, which each independently satisfy the definition of “planet” are considered a “double planet” if they orbit each other around a common point in space that is technically known as the “barycentre”. In addition, the definition of “double planet” requires that this “barycentre” point must not be located within the interior of either body.
I have more on this in my blog…
http://volerum.blog.com/967795/
http://volerum.blog.com/984093/
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Arne
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The 'barycentre' in a tripple body system would require some sort of exception rule, such as adding masses together.
Mesklin is not round.
What are their rules for moons anyways?
A 'feel good' solution for me would be: Smaller than Mercury, it's a planetoid. Smaller than 'round', it's an asteroid.
Still, I'd be inclined to call an earth-like body around a gas giant a planet.
It seems we need a table with dimensions or the most important aspects of celestial bodies, then a word for each combination of these properties. Earth orbiting Jupiter would be a: Class 3 size body with atmosphere that orbits an orbiter. Our moon would then be a: Class 2 size body without (significant) atmosphere that orbits an orbiter orbiter.
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Death 999
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We did. You did. Yes we can. No.
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The best proposal I've seen is that a planet must dominate its orbit, such that everything else in the orbit is synchronized to it, be it as a moon, a lagrange point, or a harmonic relationship (such as between Neptune and Pluto).
Pluto hardly clears its orbit out, Ceres even less so; all the other planets do.
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Razorback
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We are all *happy campers*
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The biggest reason that the Moon is not considered part of a double-planet system is that the earth-moon barycenter is about 1/3 of the way from earth's crust to it's core.
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