IAU unveils definition of "planet" - and Pluto is off the list

[derby378]

According to the International Astronomical Union:

Planet: a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a ... nearly round shape, and has cleared the neighborhood around its orbit.

Pluto's orbit takes it into the same neighborhood as Neptune, so it's off the list. We are down to eight planets again.

http://www.chicagotribune.com/news/nationworld/sns-ap-pluto-demoted,0,5183551.story?coll=chi-newsbreaking-hed

[TimeChaser]

1. Nooooooo!

:cry:

[Marr]

2. I'd say that's a good definition.

"My Very Eager Mother Just Served Up Nachos".

[derby378]

5. My Very TALENTED Mother

Earth's "real" name is Terra.

:evilgrin:

[Marr]

8. I'm calling the IAU on your ass.

:D

[Bill McBlueState]

13. I'm also supporting the nacho resolution

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=102&topic_id=2472654&mesg_id=2472739

When does the IAU start debating that?

[Poll_Blind]

3. Yes! I was afraid for a second that Charon and Xenia had put a shiv...

...in Pluto's ear because I wasn't expecting them to go that way with the decision. I think this new model works fine. And it's not like Pluto's off the air- it'll be in syndication for millions of years more.

PB

[rman]

4. Doesn't that mean Neptune is also not a planet,

since Pluto is in the neighborhood of its orbit?

[derby378]

6. Neptune has a more predictable and regular orbit than Pluto, but...

...your question is very valid. What if Neptune's orbit was erractic instead of Pluto's? it would still look like a planet to me - ring, moons, and all.

[rman]

14. Both orbits are predictable, neither is erratic

It's just that Pluto's orbit is more elliptical. Also the kind of orbit is not a condition in the new definition.

It seems strange to me to disqualify Pluto as a planet on the basis that it hasn't cleared Neptune out of it's orbit, but not Neptune in spite of the fact that it has not cleared Pluto out of its orbit.
If either could clear the other out of its orbit, it is Neptune because it has much more mass than Pluto.

[derby378]

15. I tend to agree with you, and here's why

Sure, Pluto's orbit is unusual, especially since Pluto's orbit occasionally brings it closer to the sun than Neptune. But there's another planet orbiting the star Mu Arae, which is almost 50 light-years away and very similar to our own sun. This planet, currently labelled Mu Arae b, has at least one and a half times the mass of Jupiter (our largest and most massive planet), but it has an orbit even stranger than Pluto's. If Mu Arae b orbited our sun, it would cross the orbit of both Earth and Mars – and occasionally threaten to smash into Venus!

Orbit alone, no matter how weird it is, seems insufficient to disqualify Pluto as a planet. The astronomers may have spoken, but the real debate over Pluto is far from over.

[rman]

19. I understand Pluto is now classified as a dwarf planet,

which i think is appropriate.
Basically it's still a planet...

[xchrom]

7. son. of. a. bitch.

i can't believe they did that.
doggone it -- i loved our 9 planet scenario.

[soothsayer]

9. yeah, well EFF them! Pluto's still a planet to me. (don't mess with

pluto, dammit!)

BOO

[Cooley Hurd]

10. This pisses Pluto off...

[Crankie Avalon]

11. Next they'll move it under the Department of Homeland Security...

...and put some "Arabian Horse Foundation"-guy over it.

[FSogol]

12. First they took away the Brontosaurus and now the Planet Pluto

What will be next?

[Hosnon]

16. New Mnemonic Device for Solar System:

Upon Pluto's demotion, here is the new mnemonic device for memorizing our planets:

Max
Viewed
Eight
Martians
Jogging
Swiftly
Using
Nikes

Spread the word DUers (especially teachers)!!!!

[meldroc]

17. Would that mean Earth's no longer a planet?

After all, Earth's moon is a very large astronomical body in close proximity to Earth (so large that technically Earth and Luna are actually a double planet,) so by this definition, Earth can't have been said to cleared the neighborhood around its orbit...

[LeftCoast]

18. This wouldn't have happened if we'd had paper ballots!

:D