Planet question is finally solved!

[ckam]

A committee of the International Astronomical Union... voted unanimously Tuesday to add three worlds to our solar system's planetary population. More planets will be added later, astronomers said... The IAU committee recognised two other plutons – Pluto's smaller companion, Charon, and Xena, an icy body bigger than Pluto that was discovered in 2003. In addition, Ceres, the biggest asteroid between Mars and Jupiter, will regain the planetary status it enjoyed in the 19th century.

[cosmo_uk]

Put this in your textbooks!

http://www.iau2006.org/mirror/www.iau.o ... u0601a.jpg

[Chef StiX]

What no love for Sedna?

[BMAONE23]

By the very definition provided though, Charon wouldn't / shouldn't be a planet. It is a moon of Pluto. Granted it may be large enough to exert a greater influence on the orbit of Pluto than most moons do on their host planets but it still directly orbits Pluto and not the sun. Or else our moon would be a planet as it to orbits the sun indirectly and is significantly larger than Charon.
http://www.space.com/scienceastronomy/0 ... ition.html

[iamlucky13]

Because the barycenter (common orbit point) of the Pluto-Charon group is outside of either body's radius, neither one is considered to genuinely dominate the other gravitationally, so it's considered a binary system.

I've got mixed feelings about the definition, but my objections are mostly knee-jerk or historical. Kids will still learn about the nine original planets with Roman names for a while, but it's not a closed set. I guess it's no more confounding ultimately than extra-solar planets, but it really takes a lot of the glamour out of the recognition. At the risk of being politically incorrect, calling a body that probably formed in the Kuiper belt and has an extreme inclination like 2003UB-313 or Sedna a planet is kind of like calling an immigrant who doesn't speak English an American. He's here and he's got his papers, but he still doesn't fit in.

[orin stepanek]

I like the new rules defining a planet. After all they were formed pretty much the same as the other planets; not their fault that we are finally able to find them. Maybe some day there will be 200 or more, so what?! If we grew up with them we wouldn't think anything about it. They are all a part of Sol's family. You shouldn't disown a son just because he's a runt. 8) We can always put an * around the first 9.
Orin

[BMAONE23]

Because the barycenter (common orbit point) of the Pluto-Charon group is outside of either body's radius, neither one is considered to genuinely dominate the other gravitationally, so it's considered a binary system.

The other two moons though, appear to orbit pluto in nearly circlar orbits that seem to be in the same geometric center as Charon's orbit. At least every graphic I've seen to date shows the Pluto system as 1 main body planet with three moons in circular orbits that center on Pluto. It would be interesting to see if the other two moons in fact orbit the barycenter or the main body. I would agree with the binary idea if they orbit the barycenter.

I think they should name the two new moons Goofey moon and Minnie moon.

[ckam]

I like the new rules defining a planet.

which are:

A planet is a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet.

[harry]

Hello All

As chef said,,,,,,,,,,,,,,,,,,,,what about Sedna?

As the song goes,,,,,,,,,,,,,,What about me,,,,,

Link: Sedna
http://antwrp.gsfc.nasa.gov/apod/ap040827.html
http://antwrp.gsfc.nasa.gov/apod/ap040316.html


Solar System Object Larger than Pluto Discovered
http://antwrp.gsfc.nasa.gov/apod/ap050731.html


Solar System Extrema
http://seds.lpl.arizona.edu/nineplanets ... ml#largest

Image Archive: Solar System
http://www.spacetelescope.org/images/ar ... r+system//

The Solar System and its bodies.
http://www.nineplanets.org/

Voyager at 90 AU
http://antwrp.gsfc.nasa.gov/apod/ap031120.html

[Qev]

As the song goes,,,,,,,,,,,,,,What about me,,,,,

Not a Nihilist Spasm fan, are you Harry?

[Orca]

If this decision holds, the word "planet" doesn't have much meaning anymore.

Personally, I think that only the major bodies orbiting the sun within the plane of the system should be "planets" and everything else should be considered "planetoids." Yes, Pluto should be demoted.

Well, that's my two bits of copper.

[harry]

Hello Orca

I think planets should be defined by size (limit) and their function, as in moon or not.

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smile,,,,,,,,,,,,,,,,,I thought size did not matter


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What about solar system of stars?

What about solar system of galaxies? as in the milkyway and its small galaxies rotating around. ooops that would be a galaxy system.

[orin stepanek]

Watch list for possible planets!
http://en.wikipedia.org/wiki/Candidate_planets
Orin

[cosmo_uk]

update: the votes have been cast at the IAU, proposal rejected

http://news.bbc.co.uk/1/hi/world/5282440.stm

Pluto demoted, no others promoted. We've now only got 8 planets

[orin stepanek]

It's sad; but a decision had to be made. It was exciting for a while. What about mercury? Mercury is smaller than Titan; but I guess it has a cleared orbit.
Orin

[orin stepanek]

http://en.wikipedia.org/wiki/Talk:2006_ ... t#Petition
Maybe the fat lady hasn't sung yet.
Orin