The CfA is a collaboration of Harvard College Observatory (HCO) and Smithsonian Astrophysical Observatory (SAO) and home to Harvard's Department of Astronomy.

News Releases

October 16, 2014

Why is the Sun's million-degree corona, or outermost atmosphere, so much hotter than the Sun's surface? This question has baffled astronomers for decades.

September 22, 2014

What is a planet? For generations of kids the answer was easy. A big ball of rock or gas that orbited our Sun, and there were nine of them in our solar system. But then astronomers started finding more Pluto-sized objects orbiting beyond Neptune.

Latest Science Update

October 17, 2014

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.

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