Smithsonian Astrophysical Observatory

Science Updates


Stars frequently form in crowded environments. By combining the resources of multi-wavelength missions like Chandra in the X-ray and Spitzer in the infrared, astronomers are able to resolve ambiguities and assemble a much more complete census of cluster content and the individual properties of the population.


The North Star, Polaris, is a Cepheid variable: one whose mass, age and physical conditions generate periodic oscillations with a period proportional to the star's intrinsic luminosity. This extraordinarily useful property of Cepheid variables, discovered and calibrated at Harvard by Henrietta Leavitt starting in 1908, allows them to be used as cosmic distance calibrators.

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.