Smithsonian Astrophysical Observatory

Science Updates


Most galaxies lie in clusters containing from a few to thousands of objects. Our Milky Way, for example, belongs to the Local Group, a cluster of about fifty galaxies whose other large member is the Andromeda galaxy about 2.3 million light-years away.


Life on Earth is dominated by photosynthesis, the process by which green plants and some organisms use sunlight at visible wavelengths to synthesize carbon-based nutrients from carbon dioxide gas and water. Photosynthesis arose relatively early in Earth's evolutionary history, perhaps as long ago as three billion years.

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.