Look westward for the four stars of the Great Square. You’ll find them in the west at nightfall. The Great Square will sink toward the west-northwest horizon as evening deepens, but this famous pattern of stars will remain in view until around mid-evening (at mid-northern latitudes).
Keep in mind that our sky chart covers a larger portion of sky than our charts usually do. The Great Square is so large that your hand can slip in between any two Great Square stars. Hold your hand at arm’s length whenever measuring distances on the sky’s dome.
Focus on the top star of the Great Square on the above sky chart. If you look carefully, you’ll see the constellation Andromeda as two streamers of stars jutting up from this uppermost Great Square star. The two streamers mimic the shape of a cornucopia or a bugle.
Go to the second star upward on each streamer: Mirach and Mu Andromedae (abbreviated Mu on the sky chart). Draw an imaginary line from Mirach through Mu, going twice the Mirach/Mu distance. You’ve just landed on the Andromeda galaxy!
On a dark night, the Andromeda galaxy looks like a faint, blurry patch of light. If you can’t see it with the unaided eye, your sky might not be dark enough.
Bottom line: The four stars of the Great Square of Pegasus are easy to find, and they can help you locate the Andromeda galaxy. Ready? Let’s star-hop!