4 - All-Sky Surveys in the Transition Years 1950–1975

Summary

Two new wide-field photographic survey telescopes were placed into operation soon after World War II, and two new nearly-all-sky galaxy surveys emerged: the Lick Observatory Shane and Wirtanen survey and the National Geographic Palomar Observatory Sky Survey. These made it possible for the first time to study the galaxy distribution in 2D as projected onto the sky. Both Shane and Abell found evidence for galaxy superclusters, but Zwicky remained steadfast in saying that superclusters do not exist. Starting in 1953, Gerard de Vaucouleurs studied the properties of the Local supercluster showing that only 10 percent of the local volume of space is occupied by groups of galaxies. Table 4.1 lists all known galaxy superclusters from this early era. The subject of cosmic voids did not arise in a formal sense, but Neyman and Scott devised a model of the galaxy distribution showing that all galaxies might all belong to groups or clusters of galaxies. Still, some cosmologists remained holdouts for homogeneity.