The Sky Today on Saturday, July 25: Great Square rising
Look for the Great Square of Pegasus in the east late this evening, bounded by four stars — including one in a neighboring constellation
Rising in the east around 10:30 P.M. is the Great Square of Pegasus, marked by four bright stars. Credit: Stellarium
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July 24: The Moon passes Antares
Rising in the east around 10:30 P.M. local daylight time is the Great Square of Pegasus, made up of four stars: Algenib, Markab, Scheat, and Alpheratz. But of these four, only the first three on the list are technically in the constellation Pegasus, cataloged as Gamma (γ), Alpha (α), and Beta (β) Pegasi. Alpheratz is cataloged as Alpha Andromedae, part of Andromeda the Princess.
Despite its location on modern charts, the late stellar expert Jim Kaler suggests Alpheratz was once part of Pegasus proper, as its ancient name can be translated to “the horse’s shoulder.” The constellations have undergone many changes throughout the millennia, and it is only in recent decades that we have come to use an established, universally accepted system of 88 constellations and their boundaries, created in 1928 by the International Astronomical Union.
Related: Who made the present-day constellations and why do they look the way they do?
Sunrise: 5:52 A.M.
Sunset: 8:20 P.M.
Moonrise: 5:59 P.M.
Moonset: 1:54 A.M.
Moon Phase: Waxing gibbous (89%)
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 10 P.M. local time from the same location.
Alison Klesman is senior editor of Astronomy magazine. She holds a Ph.D. in astronomy and has studied a variety of topics, from minor planets to supermassive black holes.
