So, are we in a 12 planet Solor System?

[Winner]

Yeah but then they'll take a vote and call it a 'differently sized planet of color'.

Well, if Nemesis existed, it would have to be very, very large.

 

[Gelion]

Why not keep things status quo?

 

[Bozo Erectus]

Why not keep things status quo?

Because theres no point in belonging to the oh so prestigious International Astronomical Union if you cant tell billions of people to throw out all of their science books.

 

[Perfection]

Why not keep things status quo?

Well, having to classify an object larger then Pluto sort of throws a wrench in the works

I'm not an astronomist but doesn't (a) implies (d) ?

Not exactly

You can see here that both moon paths (purple) go around the orbit of its planet but in the case of the latter it appears from an observer stationary relatvie to the sun to be going mostly in a circular orbit around the sun with some swaying back and forth across the planet's orbital path (this is the case with our moon). So in a way you can think of it as mostly orbiting the sun from that perspective. However no perspective makes it not a satellite of the planet.

 

[Winner]

Why not keep things status quo?

Because the status quo is not good?

 

[Gelion]

Because the status quo is not good?

"Stable in not sexy" - Mr. Garibaldy, Babylon 5, last episode


Thanks Perfection, although having to rewrite the astronomy books is more of pain than including one little line on "history of exploration". How big are the other two objects?

 

[Winner]

I think kids won't mind it, they won't have to remember one name! Also, the change of textbooks will boost the printing industry

 

[Marla_Singer]

Not exactly

You can see here that both moon paths (purple) go around the orbit of its planet but in the case of the latter it appears from an observer stationary relatvie to the sun to be going mostly in a circular orbit around the sun with some swaying back and forth across the planet's orbital path (this is the case with our moon). So in a way you can think of it as mostly orbiting the sun from that perspective. However no perspective makes it not a satellite of the planet.

So is a soccer ball a planet ? After all, it's round and is in orbit around the sun...

j/k

 

[Winner]

So is a soccer ball a planet ? After all, it's round and is in orbit around the sun...

j/k

And with some bad luck, it also cleared all windows in the neigborhood

 

[Perfection]

Thanks Perfection, although having to rewrite the astronomy books is more of pain than including one little line on "history of exploration". How big are the other two objects?

Xena is a smidge larger then Pluto, the other two objects in the propoed were Ceres which is rather small compared to Pluto (about 1/10 the mass and 1/12 the volume) and Charon (Pluto's "Moon") which is about 1/5 the mass/volume of Pluto.

What is important to note is that there are numerous bodies between Pluto and Ceres that probobly would've been considered planets shortly after adopting the first resolution.

Luckily they came to thier senses and decided that was not the way to go.

 

[steviejay]

I'm glad they did, I had a feeling they would bottle it and count everything as a planet.... the number of 'planets' would jump up every few months when they point a telescope at another bit of sky and see what's there

 

[Sims2789]

Why is Earth a planet? The differences between it and the Jovians are than that between Earth and the Plutonian planets?

Why not just call Pluto, 2003 UB313, etc. "dwarf planets", like Wikipedia's doing?

Ceres shouldn't even cut it as a dwarf planet, though.

EDIT: This is what the IAU has decided, except Ceres is also a dwarf planet.

 

[Perfection]

Why is Earth a planet? The differences between it and the Jovians are than that between Earth and the Plutonian planets?

Earth is master of its orbital domain, Pluto is not. Earth keeps the swath of space it orbits around nice tidy and free of debris, Pluto wallows in the filth of other objects.

Why not just call Pluto, 2003 UB313, etc. "dwarf planets", like Wikipedia's doing?

That's the plan. These things are called "dwarf planet" the important thing is that a "dwarf planet" is not a "planet". "Dwarf planets" according to the IAU (and then shown on wikipedia) are bodies that aren't "planets" because they aren't masters of thier orbital domain but retain the other features (direct solar orbit, rounded by gravity)

Ceres shouldn't even cut it as a dwarf planet, though.

It does in there definition because it has been rounded by gravity.

 

[Gogf]

Ceres shouldn't even cut it as a dwarf planet, though.

Why not? What makes Pluto worthy of dwarf planetness and not Ceres?

 

[croxis]

Can we just go back to studying these things instead of arguing what to call them? =P

 

[Perfection]

Can we just go back to studying these things instead of arguing what to call them? =P

Hey, we never stopped! This is just a PR stunt to get more attention so we can study them even more! KBO= Kick-Butt Objects!

 

[The Last Conformist]

Why is Earth a planet? The differences between it and the Jovians are than that between Earth and the Plutonian planets?

The chief reason is sheer gravitational clout. As Perf says, the terrestrials and jovians dominate their orbital regions in a way no other objects in the solar system can. Another similarity is that both have (or are believed to have) large amounts of metal in their cores, whereas the plutonians are made up chiefly of ices and silicates.

From a pragmatic viewpoint, the fact that plutonians grade seemlessly into undeniably non-planetary objects while jovians and terrestrials do not makes the present definition much easier to use than the proposed one.


Incidentally, assuming that Xena's density isn't much above Pluto's, the size gap between the largest (known) plutonian and the smallest terrestrial is bigger than that between the largest terrestrial and the smallest jovian. We've become used to thinking of Xena as "large", because it outsizes Pluto, but it's a pebble compared to the real planets.

 

[kryszcztov]

Yeah, that's why my definition which is a little more complex I view is better, but it's a small quibble as any planet will remove just about everything in its orbital path except at it's L4 and L5 points.

Can you tell me what does "remove everything in its orbital path" mean ? For instance, the Earth has the Moon around it... I feel there is something that isn't said but is very important to understand. L4 and L5 are Lagrange points at -120° and +120° on the orbital path, like for some Jovian asteroids ??

 

[Chairman Meow]

Mary Virginia eats many jam sandwiches under Ned's Porch.
Now it has to be...
Mary Virginia eats many jam sandwiches under Ned

My very educated mother just said "Uh, no."

And don't forget the most useful of all the mnemonics: mvemjsun.

 

[Perfection]

Can you tell me what does "remove everything in its orbital path" mean ? For instance, the Earth has the Moon around it... I feel there is something that isn't said but is very important to understand. L4 and L5 are Lagrange points at -120° and +120° on the orbital path, like for some Jovian asteroids ??

Well take the asteroid belt for instance, it's a whole bunch of small bodies all over the place within a certain distance from the sun. The orbits of the planets are different, there are not small bodies all over the orbital locus. Rather, all but a small amount of bodies in unstable orbits have either been ejected from the area or given some special stable orbital relationship with the planet, these include orbiting with the planet at the L4 or L5 points, becoming a captured moon, going into a resonance orbit or going into a horseshoe orbit.