Astronomer Biography

Allan Sandage

Allan Sandage was born on June 18, 1926. He was an American astronomer, best known for his work with Edwin Hubble.

            In 1948, Sandage graduated from the University of Illinois, and went on to receive a PhD from the California Institute of Technology in 1953, with astronomer Walter Baade as his mentor. Sandage worked as an assistant to cosmologist Edwin Hubble, and continued his research after Hubble’s death in 1953. In 1952, Sandage proved both prestigious astronomers to be mistaken in a study of Cepheid variable stars, showing that the brightest stars in galaxies were of approximately equal inherent intensity, and that Baade was mistaken in the case of H II regions which he found not to be stars and inherently brighter than the brightest stars in distant galaxies. Sandage then calculated the age of the universe to be approximately 5 and a half billion years, which was an increase of a factor of 1.5 from what was previously calculated.

            Allan Sandage then began working at the Palomar Observatory, and in 1958 published the first good estimate for the Hubble constant. He edited Hubble’s previous value of 250 km/s/Mpc to 75, which is close to the current accepted value. Sandage also did studies on globular clusters, calculating their age to be around 25 billion years. This calculation led him to think that the universe did not only expand, but it expanded and contracted at a period of 80 billion years. He co-wrote a paper with Donald Lynden-Bell and Olin J. Eggen during his studies on the formation of galaxies in the early universe. Sandage discovered jets erupting from the core of the M82 galaxy, likely caused by massive explosions in the core, and is noted for this discovery. In 1959, Sandage married fellow astronomer Mary Connelley. They had two sons.

During his career, Sandage published over five hundred papers. He won many awards over the course of his career for his work in astronomy, including the notable Bruce Medal in 1975. A main-belt asteroid was named after him, 9963 Sandage. He actively researched at the Carnegie Observatory until his death in 2010, at age 84.