This constellation heralds the return of fall for observers in the northern hemisphere. Look for its trademark square of stars in the eastern sky around 10 p.m. Each night, as the month progresses, it will make its way higher and westward. The southernmost star of the Great Square—and brightest in the constellation—is Markab (Arabic for “saddle”). About midway between Markab and Altair (in the constellation Aquila) is the star Enif, which is almost as bright as Markab. Enif marks the nose of Pegasus, the horse, and it is actually a double star system. One of the most impressive globular clusters in the sky lies just up and to the right of Enif—M15. Use binoculars or a telescope to zoom in and resolve individual stars.