How is a star born? Helping scientists find out is the mission of the Galaxy Evolution Explorer spacecraft, or GALEX. GALEX orbits Earth looking out into space. Way out!

GALEX sees almost to the very edge of the universe! It is especially looking for star nurseries. These are places where new stars are forming inside galaxies. Galaxies are clusters of gas, dust, stars, planets, moons, and various strange objects such as black holes. Our own Milky Way galaxy contains over 200 billion stars. The entire universe probably contains over 100 billion galaxies.

GALEX can see these hot, baby stars quite well, because they shine brightly in ultraviolet, or UV, light. UV light is invisible to us. Very little of it can get through the atmosphere to Earth's surface. But GALEX, high above Earth's atmosphere, is especially made to detect this kind of light. By studying galaxies near and far away, especially those that glow strongly in UV, scientists can understand better where and how stars are formed, how galaxies come to be, and how galaxies change over cosmic time.

GALEX can detect stars and galaxies that are more than a million times fainter than ones we can see with our eyes from even the darkest skies here on Earth. It will be the first mission to map most of the sky and look beyond our own galaxy. Its all-sky map will also help astronomers find the most interesting looking galaxies for future study in detail using other telescopes.