Allan Rex Sandage's Observational Cosmologist

Allan Rex Sandage was an American observational cosmologist, who seen as one of the most influential astronomers of the 20th century. He rightfully earned the nicknames “Mr. Cosmology” and the “Super Hubble”, as continued and refined the work of Edwin Hubble and made many discoveries of his own along they way, including discovering the first quasar and producing the first reasonable estimate for the Hubble Constant (h0). Throughout his career, some of Sandage’s notable awards include the Helen B. Warner Prize for Astronomy (1957), the Eddington Medal (1963), the Gold Medal of the Royal Astronomical Society (1967), the Rittenhouse Medal (1968), the National Medal of Science (1970), the Elliot Cresson Medal (1973), the Bruce Medal (1975), the Crafoord Prize (1991), the Gruber Prize in Cosmology (200) and became a Fellow of the Royal Society. Born on 18 June 1936 in Iowa City, Iowa, Allan Sandage was the only child of business professor Charles Harold
Being trained in securing photometric data on globular clusters using the Mount Wilson 60-inch, Sandage, Halton Arp, and William Baum began searching for the main sequences of globular clusters, something that had not yet been discovered. Globular clusters are tightly packed groups of ancient stars which are typically located near the outer regions of the galaxy. Although Messier 92, located in the northern part of the constellation Hercules, was their first target, Sandage chose Messier 3, located in the northern constellation Canes Venatici, for his thesis. They discovered that the cluster ages were at least 3 billion years old, which can be used as an indicator for the age of the universe. This indicator was more consistent with geological time estimates for the earth’s age than the 1.8 billion derived through Hubble’s expansion value, as there is geological evidence on earth that suggests the earth is older than 1.8 billion years