Twenty-five years ago, NASA launched one of the most ambitious experiments in the history of astronomy: the Hubble Space Telescope. In honor of Hubble's landmark anniversary, NOVA tells the ...

The two keys to Edwin Hubble's breakthrough discovery were forged by others in the 1910s. The first key, the period-luminosity scale discovered by Henrietta Leavitt, allowed astronomers to ...

NASA's Hubble Space Telescope has discovered that a system of asteroids in the distant Kuiper Belt may be triplets, not twins as previously suspected. If so, the stable trio of icy space rocks ...