Barbara J. Feldman

A group of stars that forms a picture is commonly called a constellation. Astronomers, however, call these star pictures asterisms, and have a slightly different definition of a constellation. Scientists divide the sky into eighty-eight official constellations, so that every point in the sky is contained within only one. As you peruse today’s crop of sites, keep both these definitions in mind, because some sites use the astronomer’s definition, and others do not.