A few days ago scientists confirmed that there is liquid water on Enceladus one of Saturn's 53 or so moons. The surface of Enceladus is covered in a thick sheet of ice but NASA's Cassini spacecraft which has been orbiting Saturn since 2004 has sent back images of geysers of ice, water vapor and organic compounds shooting out from cracks in the ice at the south pole of Enceladus. This was the first sign that there may be liquid water below the ice. Also, NASA noticed slight changes in Cassini's trajectory and the wavelength of it's radio signals which suggested that Enceladus has a greater mass at the south pole. In addition, it has long been known that Enceladus is flatter at the south pole than anywhere else. The best explanation for both phenomena is that there exists a large body of liquid water, which is both denser and has less volume than ice, underneath the south pole. This subterranean ocean is estimated to be about the size of lake superior and is particularly exciting because it is thought to sit above a layer of rock that could provide chemical reactions which when coupled with the organic molecules in the geysers could possibly produce simple organisms. Unfortunately Cassini doesn't have the instruments needed to properly test the makeup of the molecules in the geysers and the ice above the lake on Enceladus is somewhere around 20 miles thick so a much more sophisticated robot would need to be sent in order to search for life.

Below are a Cassini picture of the ice plumes at the south pole and a rendering of Enceladus's cross section.