Saturn’s bright satellite Enceladus is covered with water ice that reflects almost all the Sun’s light back into space.
The geologically active moon, discovered in 1789 by William Herschel, has craters, ridges and smooth plains. Most spectacularly, Enceladus has geysers that spew frozen water thousands of kilometres into space.
Stay curious. Learn more about Enceladus from this beautiful TED Talk by the Saturn-studying scientist (and project manager for the Cassini spacecraft) Carolyn Porco entitled "Could A Saturn Moon Harbor Life?" (3:27)
"Here on Earth we live on a planet that is in orbit around the Sun. The Sun itself is a star that is on fire and will someday burn up, leaving our solar system uninhabitable. Therefore we must build a bridge to the stars, because as far as we know, we are the only sentient creatures in the entire universe. When do we start building that bridge to the stars? We begin as soon as we are able, and this is that time. We must not fail in this obligation we have to keep alive the only meaningful life we know of."
Astronomers Surprised By Large Space Rock Less Dense Than Water
Kuiper belt object challenges planet-formation theories.
A planetary scientist has identified the largest-known solid object in the Solar System that could float in a bathtub. The rock-and-ice body, which circles well outside the orbits of the planets, is less dense than water — although a bathtub big enough to hold it would stretch from London to Frankfurt.
The body, dubbed 2002 UX25, lies in the Kuiper belt, a reservoir of dwarf planets, comets and smaller frozen bodies beyond the orbit of Neptune. The object’s low density and size — it is 650 kilometres wide — seem to conflict with a leading model for the formation of large solid bodies in the Kuiper belt and throughout the Solar System. Planetary scientist Michael Brown of the California Institute of Technology in Pasadena reports its density measurement in an upcoming issue of The Astrophysical Journal Letters, with a preprint available on the arXiv online repository.