What makes a planet? Pluto insights....

[Greebe]

Hit that on the nail head CJ

Doc you're right and so am I. Only added to their reasoning behind the change, something you left out.

Perhaps it should be taught in Astronomy 102

[KvHagedorn]

You know, we already have the "gas giant" classification. Clearly Jupiter, Saturn, Uranus, and Neptune are all much larger than the Earth and inner planets, and of totally different composition, so they are in a class by themselves. Go ahead and call Pluto and Ceres planets, just append "dwarf" to the beginning and be done with it. There we have it.. three pretty distinct classes of planet.

[dbdg]

How do you feel about dog breeds!?

I think there should be one, 'dog' make it much easier for me to cope.

Classification doesn't worry me at all just wondered what would happen in a few years when we find them.

[cjolley]

Classification doesn't worry me at all just wondered what would happen in a few years when we find them.

All the textbooks ever printed about planets would explode in a massive atomic blast that would destroy the Earth.
But that's another story.

[Nowhere]

I'm not really bothered about the distictionion of Pluto either way but I do have a question.

What if we discover some planets (may already have) that are 100 times larger then Jupiter, will we then classify them as Giant planets, if so that seems a little silly as we would end up with three types of planets.

Also what if out of the next 5000 planets we discover, they all have orbits like Pluto and not like Earth, how will that alter things?

Hey, if we discover things that make current rules look unfit (that's why there are new rules - we are most probably starting to discover dozens Pluto - like objects in our system), we change the rules, that's the thing about science...

And BTW, something 100 times larger then Jupiter could only be a star. (when it comes to mass; when it comes to size Jupiter is around as big as object of its type can be)

[Dr Mordrid]

And BTW, something 100 times larger then Jupiter could only be a star. (when it comes to mass; when it comes to size Jupiter is around as big as object of its type can be)

At ~13 Jupiter masses a Jupiter-like body is dense enough to fuse deuterium (hydrogen with both a proton and a neutron) and become a brown dwarf. Below that it's considered a planet, at least until the next IAU meeting

The full-blown star ignition point is ~75 Jupiter masses.