December 20: Walter Sydney Adams

Walter Sydney Adams

December 20, 1876 – May 11, 1956

Walter Sydney Adams was an American astronomer.

He was born in Antioch, Syria to missionary parents, and was brought to the U.S. in 1885. He graduated from Dartmouth College in 1898, then continued his education in Germany. After returning to the U.S., he began a career in Astronomy that culminated when he became director of the Mount Wilson Observatory.

His primary interest was the study of stellar spectra. He worked on solar spectroscopy and co-discovered a relationship between the relative intensities of certain spectral lines and the absolute magnitude of a star. He was able to demonstrate that spectra could be used to determine whether a star was a giant or a dwarf.

In 1915 he began a study of the companion of Sirius and found that despite a size only slightly larger than the Earth, the surface of the star was brighter per unit area than the Sun and it was about as massive. Such a star later came to be known as a white dwarf.

Along with Theodore Dunham, he discovered the strong presence of carbon dioxide in the infrared spectrum of Venus.

Adams received the Gold Medal of the Royal Astronomical Society (1917), the Henry Draper Medal (1918), the Bruce Medal (1928) and the Henry Norris Russell Lectureship (1947).

The asteroid 3145 Walter Adams and a crater on Mars are named in his honor. The crater Adams on the Moon is jointly named after him, John Couch Adams and Charles Hitchcock Adams.