Smithsonian Astrophysical Observatory

Science Updates

04/18/2014

Atomic hydrogen is the lightest and by far most abundant element in the universe. When it is exposed to ultraviolet light, its single electron can be stripped from the atom, a situation that arises near stars that are hot.

04/11/2014

Galaxy clusters are groupings of several to thousands of galaxies. Most galaxies are members of a cluster. In our own case, the Milky Way is a member of the "Local Group," a band of about fifty galaxies whose other large member is the Andromeda galaxy about 2.3 million light-years away.

The Smithsonian Astrophysical Observatory (SAO) is a "research institute" of the Smithsonian Institution. It is joined with the Harvard College Observatory (HCO) to form the Harvard-Smithsonian Center for Astrophysics (CfA). Because these research activities share Harvard and Smithsonian staff and resources, the links at this website will take you to information posted on the "CfA" pages.