Constellations were officially designated in the 1930s. Boundaries were drawn along the then current celestial right ascensions and declinations. Today these boundaries have processed a small amount but the constellations still have their 1930's shape.

At one time stars were frequently located in two or more constellations, simultaneously. Sometimes the star bore two names which depended on which constellation you were considering. For example, Alpheratz Alpha Andromedae was a corner of the Great Square in Pegasus as well as the top of Andromeda's head. Today Alpheratz belongs to entirely in Andromeda.

In addition to the 88 recognized constellations, there are many asterisms which are so famous that people think of them as constellations. The Summer Triangle Lyra, Cygnus and Aquila portions, the Praesepe Beehive, the Pleiades Seven Sisters and the Hyades are common examples. -[Les Coleman]