A

David

Darling

pluton

In geology, a pluton is any body of igneous rock that solidified below the Earth's surface.

 

In planetary astronomy, pluton was a proposed category of planetary object, of which Pluto would have been the prototype, consisting of planets that takes at least 200 yr to complete one orbit of the Sun. Astronomers instead adopted the term "dwarf planet" to distinguish smaller planetary objects from the eight "classical planets," Mercury through Neptune.