Andromeda II [SEP] time of discovery
Andromeda II
Andromeda II (And II) is a dwarf spheroidal galaxy about 2.22 Mly away in the constellation Andromeda. While part of the Local Group, it is not quite clear if it is a satellite of the Andromeda Galaxy or the Triangulum Galaxy.
It was discovered by Sidney Van den Bergh in a survey of photographic plates taken with the Palomar 48-inch (1.2 m) Schmidt telescope in 1970 and 1971, together with Andromeda I, Andromeda III, and the presumable non- or background galaxy Andromeda IV.
Spectra
II, he took advantage of wartime blackout conditions (which reduced light pollution), to resolve stars in the center of the Andromeda Galaxy for the first time. These observations led him to define distinct "populations" for stars (Population I and Population II). The same observations led him to discover that there are two types of Cepheid variable stars. Using this discovery he recalculated the size of the known universe, doubling the previous calculation made by Hubble in 1929. He announced this finding to considerable astonishment at the 1952