ABSTRACT
From the earliest days of astronomy, mankind has always been alone in the universe. As many as 5,000 more exoplanets have been discovered since then. Most are somewhere between Earth-sized and Neptune-sized planets, and all of them are probably uninhabitable by any form of life as we know it. The astronomers’ invasion of science fiction continues, as the scientific search intensifies for life elsewhere in our solar system. One of Jupiter’s moons, Europa is believed to have an underground ocean of liquid water that is larger than all of Earth’s oceans combined. Saturn’s largest moon has lakes of methane on its surface, and is the only body in our solar system other than Earth that contains any kind of liquid on its surface.
