Pluto As A Planet or Not.....

Hello all,

As the designated "company astronomer" (as many of you also are),
whenever something astronomical creeps onto CNN, I usually field a
bunch of questions from colleagues.

I've been asked on more than one occasion about if Pluto is really a
planet or not. I tend to lean towards it not being a planet, but I
really don't know all the sides of the issue.

What I do know, which leads me to believe that it's not a planet:

Pluto isn't much bigger than our moon (but then again neither is
Mercury)
It has an inclined orbit around the Sun that is decidedly non-planetary

But then I'm a little confused about the atmosphere issue. Pluto does
have an atmosphere....sometimes....right? Doesn't it freeze and fall
to the surface depending on where it is in its orbit? Are there any
asteroids that have an atmosphere? How about any asteroids that are of
similar size that have a similar orbit to Pluto?

I just can't really make up my mind on the topic and was hoping those
of you more "in-the-know" could help out.




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