Smithsonian Astrophysical Observatory

Science Updates


Supermassive black holes containing millions or even billions of solar-masses of material are found at the nuclei of galaxies. Our Milky Way, for example, has a nucleus with a black hole with about four million solar masses of material.


The solar chromosphere is the region between the Sun’s surface and its hot, million-degree corona. Within this complex interface zone, only a few thousand kilometers deep, the density of the gas drops by a factor of about one million and the temperature increases from about five thousand to one million kelvin.

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.