Transcript: Jupiter's Europa is one of the Galilean satellites. At 3,100 kilometers in diameter it's similar in size to Io and similar to the Earth's moon. Europa looks completely different from Earth's moon however. It has an uncratered, bright surface of frozen water. In 1996 the Galileo space probe took detailed pictures of the surface of Europa and showed that the surface is covered with a jostling icepack constantly breaking and reforming. The icepack’s thickness ranges from a few hundred meters to a few kilometers, and underneath the icepack is probably several kilometers of depth of liquid oceans. That far from the Sun the water is kept liquid by tidal heating which creates heat in the Europan interior which then melts the water under the icepack. This exciting discovery is the confirmation that the oceans of the Earth are not unique even in the solar system.