with a massive impactor striking the young Pluto in the Solar System's ancient past, thereby casting off a large field of ice and rock debris which subsequently coalesced into the proto-Charon.

Clyde Tombaugh discovered Pluto in 1930 at Lowell Observatory in Flagstaff. Here's how Pluto won - and lost - its planetary ...

However, some scientists argue that Pluto should be considered a planet based on geological activity rather than orbital mechanics. NASA’s New Horizons mission revealed ice mountains ...