Ice on moons

Jupiter's moon Europa is slightly smaller than our own Moon and has a diameter of around 3000 km. This moon is covered by a several kilometer thick ice layer, dominated by beautiful ridges and cracks. This ice layer is probably lying on top of a deep water ocean, and due to the abundance of liquid water, this moon is a key place when searching for life in the solar system.

Enceladus is much smaller with a diameter of around 500 km. It also has an icy surface with various cracks and ridges, but the most intriguing feature is the geysers in the south polar area.



The icy surface of Jupiter's moon Europa is filled with beautiful ridges and cracks probably created by tidal stresses, maybe in connection with the subsurface ocean. (Picture credit: NASA)


The geysers are powered by so-called cryovolcanoes that work exactly as "real" volcanoes, just with ice instead of magma. In the cryovolcanoes, the ice deep below the surface is heated by tidal forces and turned into vapor that expands to form a geyser or an explosion. On Enceladus, these geysers eject large amounts of water almost 500 km into space.


Saturn's icy moon Enceladus has immense cryovolcanism which ejects ice particles 500 km into space. This can be seen on the lower left side of the moon. To the right, a picture describing how the cryovolcanism works. (Picture credit: NASA)

Read about ice on Mars