Icy Charon

Astronomers have recently discovered that Pluto's moon Charon erupts in geysers of water ice. In fact, it looks as though Charon surface is covered in a new, thin sheet of water ise every 100,000 years.

Jupiter's moon, Europa, for example, also sports such geysers. In that case, however, scientists think the powerful gravity of Jupiyer, constantly pulling, squeezing, and flexing the interior of Europa, is the energy source for the geysers. Tiny Pluto-- now no lunger even a planet, according to the International Astronomical Union-- has no such fun with Charon. Some sientists speculate a source of radioactivity in the core of the moon could power the geysers.

When NASA's mission to Pluto and the Kuiper Belt finally arrives at Pluto in a few years, Charon might be the body putting on a show.