Images: Ocean on Titan, and salt on Mars

Also this week, on a planet labeled as a "hot Jupiter," the Hubble Space Telescope discovered the first organic compound outside our solar system. The discovery of methane on planet HD 189733b, which is 63 light-years away from Earth shows that organic compounds can be detected in extra-solar worlds. It's another step toward finding out whether or not we are alone in the universe.

Photo by NASA, GSA, and G. Bacon (STSCl)