Quote - The problem with this planet, non-planet thing is that Pluto, although actually a pluton, won't be downgraded, because it is one of the "traditional" planets, i.e., members of the public have gotten used to it being called a planet, so they will probably not remove its planet sttatus. As one of the articles on the subject said, pluto will probably be "grandfathered in as a traditional planet".

Ceres was at one time considered a planet, so if the proposed change goes into effect, it will simpley be regaining the planet status it originally had and lost about a century ago.

The moon can't be upgraded to a planet because it is clearly a sattelite of a larger body and not a planet in its own right. They might, however, invent a new category, planet-type sattelites, i.e., moons that would be considered planets if they weren't sattelites (as opposed to the majority of moons which would be asteroids or plutons). This category would include the Moon, Io, Titan, etc.

The reason Charon is being considerd for planet status, is that Pluto and Charon are so close in size, that they appear to be a bibary planet (2 planets gravitiationally bound to each other) rahter than a planet and its moon. (that status has also been proposed for the earth and the moon in the past, because of how unusually large the moon is in relation to the size of the earth - most moons are tiny by comparison to their parent planet. Even the moons like Io and tatan, which are larger than the earth, are tiny by comparison to their enormous parent palnets.

 

 

I thought anything greater that Pluto's characteristics will be a Pluton. I thought they set it so Pluto was the upper limit for a Planet (or lower limit for a Pluton).?  I may have read that wrong....

 

ratscloset
aka John