Pegasus constellation. Optical image of Pegasus, a northern constellation that is named after the Winged Horse in Greek mythology. Only the top half of the horse is depicted in the constellation: the four bright stars in the great square of Pegasus are Alpha Pegasi (Markab), Beta Pegasi (Scheat), Gamma Pegasi (Algenib), and Alpha Andromeda (Alpheratz). The nose of Pegasus is marked by Enif (Epsilon Pegasi, on the right), the brightest star in the constellation at magnitude 2.38.