“which help piece together the timeline of the galaxy’s star formation and exchange of gas between star-forming clouds and the stars themselves,” says NASA. Named after astronomer Edwin ...

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 ...

Photo: Andromeda nebula plate with Hubble's handwritten circle around the variable star he discovered In 1919 American astronomer Edwin Hubble began work at the Mount Wilson Observatory in ...