The Passing of Allan Sandage

Earlier today I learned of the passing of Allan Sandage. Allan was a tremendously broad astronomer, who had a lasting impact on fields of astronomy stretching from stellar evolution to the largest cosmological issues. He is perhaps best known for his work on the distance scale, and measurements of the Hubble Constant, but he had equally significant contributions to our understanding of stars. The prominence of his work on the Hubble Constant is in part due to the rather contentious history of this subject over much of the 90's and early 2000's. Allan was at heart a stellar astronomer, but one who found himself tied to Hubble's legacy by virtue of being Hubble's telescope assistant in the years leading up to Hubble's unexpected death in 1953. As one of the earliest pioneers (with Martin Schwarzschild) of the technique of using main sequence turnoffs to assign ages to globular clusters, Allan ...