Smithsonian Astrophysical Observatory

Science Updates


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.


Although thousands of exoplanets and hundreds of planetary systems (stars with multiple exoplanets) are now known, astronomers still don’t know whether our solar system is typical. The distributions of known planetary system parameters are strongly affected by observational biases that are not easy to disentangle from the true distributions.

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.