Sandage, Allan Rex (1926– )

US astronomer whose research has been in stellar astronomy and observational cosmology; with German-born US astronomer Martin Schwarzschild he determined ages and evolution of globular clusters in order to obtain the ages of the oldest objects known. He has calibrated all of the ‘standard candles’ to determine distances of remote galaxies and has several times presented revised estimates of the value of the Hubble constant.

Sandage became a senior researcher scientist at the Space Telescope Science Institute in 1987. In 1950 he deduced the universe's age – 10 billion years – and in 1960 he discovered quasars. He published The Hubble Atlas of Galaxies (1961) and compiled The Carnegie Atlas of Bright Galaxies. In 1991, he was awarded the prestigious Craford Prize. He also received the first award of the Cosmology Prize of the Peter Gruber Foundation (a new award of $150,000/£95,000 for achievements in cosmology), in August 2000.

Sandage was educated at the University of Illinois and the California Institute of Technology, where he earned his doctorate under Walter Baade. Since 1952 he has been on the staff of the Mount Wilson and Palomar Observatories, now the Observatories of the Carnegie Institution of Washington, where he began as a graduate student assistant to Edwin Hubble. After nearly half a century of observing with the Hale Telescope on Palomar Mountain, he now uses the Hubble Space Telescope to determine distances to galaxies using Cepheid variable stars.