Pluto's a Plutoid!

by Clifford Johnson     Department: Space

Ever wonder what Pluto is since it stopped being a planet? A dwarf planet, you say. Well, as of Tuesday, there's a new classification. It is a Plutoid. The IAU has announced in their press release:

Plutoids are celestial bodies in orbit around the Sun at a distance greater than that of Neptune that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (near-spherical) shape, and that have not cleared the neighbourhood around their orbit. Satellites of plutoids are not plutoids themselves, even if they are massive enough that their shape is dictated by self-gravity. The two known and named plutoids are Pluto and Eris. It is expected that more plutoids will be named as science progresses and new discoveries are made. The dwarf planet Ceres is not a plutoid as it is located in the asteroid belt between Mars and Jupiter. Current scientific knowledge lends credence to the belief that Ceres is the only object of its kind. Therefore, a separate category of Ceres-like dwarf planets will not be proposed at this time.

More of the background to this - such as what this all has to do with science - can be found at Asymptotia.

-cvj

Tags: pluto, plutoid