Pluto

Pluto

Pluto doesn't orbit particularly closely to the plane of the other planets - that alone should make one suspicious that it isn't. Strike 1.

Then there's it's very high orbital eccentricity - it even *crosses* the orbit of Neptune. If it was in an orbit that was rather more in the plane of the other planets, Neptune might have sucked it up long ago, barring their mutual 3:2 orbital-period resonance. Strike 2.

Finally, there's the fact that its origin is clearly as a Kuiper Belt Object that strayed too far inward toward the Sun and begin interacting gravitationally with Neptune - so it's a KBO. Strike 3 and yer out.

Terry (astrotrf)

The designation of "planet" is a linguistic, social, even political matter of little or no scientific importance, which is precisely why so many people care. If it were a useful scientific designation there would be little basis for debate. But I was happy to see Pluto reclassified because otherwise it would eventually be necessary to admit dozens of other objects as planets, which I think would be more socially disruptive. I reject the idea of grandfathering. Scientists have no business arbitrarily "grandfathering" Pluto whilest excluding larger, equally qualified objects as planets. Unfortunately, I found the earlier efforts to contrive a definition which supported Pluto's inclusion transparent. On the other hand, the definition chosen was even more contrived and disappointing.
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Mike

I know only 3 definitions for Pluto:
1) Mickey mouse's pet dog.
2) Pluto the Roman God of the Underworld.
3)The 9th Planet of our Solar System.

Kevin

Brian Staples said:

...I'm to damn old and set in my ways to change what I learned a half a century or so ago...

Brian, I'm 63 and I still think Pluto is a planet--a dwarf planet. We have dwarf galaxies and dwarf stars and no one objects to the classification. What's the problem?

Bob Schmall

I've been watching this voting with some level of fascination. I would have expected a group
composed primarily of interested amateur astronomers to be more in tune with the idea that
Pluto is *not* a planet. As I write this, the voting is about 58% is, 42% isn't - that's a sur-
prise to me.

Even as a kid in the '60s, I recall thinking that Pluto should not be classified as a planet;
its orbital parameters alone clearly pointed towards a different origin than the other 8.

As someone else pointed out, "planet" is merely whatever we define the word to mean. But I
would have expected, here, more satisfaction with a definition that excludes Pluto.

Terry (astrotrf)

Michael Sutherland said:
Most of the "classic" planets wouldn't pass the cleaning out their neighborhood requirement.

On the other hand, I think most folks would agree that such a requirement neatly
excludes the largest asteroids, such as Ceres.

And I'm sure it's understood that "cleaning out" doesn't mean devoiding the neigh-
borhood of every last rock.

Terry (astrotrf)

It just feels right that Pluto is.If not-it would be like losing a friend!

It depends on your definition of "is".

Is or isn't what?
Herb didn't say, but he did use a Disney Pluto image in the classified for this. Are we talking dogs or planets? (Now if he asks about Goofy, we know what the question was! 8) )

I personally liked the different planet classifications (terrestial, gaseous etc), we have been using these for years already, simple to add another class that would allow other objects in.

Brian