Cygnus constellation. Cygnus, the swan, is a summer constellation in the northern hemisphere, although it is far north enough to be at least partly seen year-round from many northern parts. Its brightest star is Deneb (Alpha Cygni), at upper left. This is a blue supergiant which is the 20th brightest star in the sky as seen from Earth. It is thought to be some 1500 light years from Earth, and to appear this bright at such a vast distance means it must be one of the largest and brightest stars known. It represents the tail of the swan. The bill of the swan is represented by the star Albireo (Beta Cygni), at lower right. The constellation is also known as the Northern Cross.