Four planets?

[redbird]

I don't care much whether Pluto is called a planet, though it's nice seeing people actually talk about the Solar System.

But any definition of a planet that excludes Earth and Jupiter is worthless. "Sweeps out its orbit" is a kludgy phrasing to deal with the Neptune:Pluto 3:2 resonance, but no matter how you phrase it, Pluto is still there, crossing Neptune's orbit, and half the planets in the system have associated asteroids.

Comments

[purplecthulhu.livejournal.com]

'Sweeps out its orbit' may be a simplified description of a more technical concept. I've not seen the details of the resolution though, but its meant to have been influenced by dynamicists who would be a bit more detailed than this description.

Pluto

[minnehaha.livejournal.com]

http://www.worth1000.com/emailthis.asp?entry=312604

B

[beginning.livejournal.com]

Our IT guy studied astronomy and is one of the people circulating the "re-planet Pluto" petition. This is all we talked about at work the past few days.

[barberio.livejournal.com]

"Sweeps it's orbit clear" is actualy a mistaken rephrasing of the requirement.

The requirment is "has cleared the neighbourhood around its orbit."

And further to this, 'cleared the neighbourhood', has a more specific meaning in IAU terminology. It refers to objects that share the *same* orbit as each other, not cross each others orbit.