Harvard University astronomers and Smithsonian Institution astronomers explore the cosmos together. The combination of the Harvard College Observatory (HCO) and the Smithsonian Astrophysical Observatory (SAO) is known as the Harvard-Smithsonian Center for Astrophysics (CfA).

News Releases

November 13, 2018

A new discovery reported in the Astrophysical Journal Letters might lay claim to title of the most unusual extreme class of astronomical object: very high energy (VHE) gamma-ray emitting, neutron star-massive star binary pairs.

October 17, 2018

The single most important puzzle in today's cosmology (the study of the universe as a whole) can be summarized in one question: How old is it? For nearly a century -- since the discoveries by Einstein, Hubble, LeMaitre and others led to the big bang model of creation -- we have known the answer.

Latest Science Update

November 16, 2018

The path of light is bent by mass, an effect predicted by Einstein's theory of gravity, and when a massive galaxy or cluster lies along our line-of-sight to a more distant galaxy its matter will act as a lens to image the light from that object.

SI Specific Information

SI-specific information regarding the government shutdown may be found at alerts.si.edu. SAO staff are encouraged to review the website for updated information