On this moonlit night, we present the four stars of the Great Square of Pegasus, which should be bright enough to withstand tonight’s moonlit glare. The Great Square is your ticket to finding the galaxy’s south window. Around 9:00 p.m. this evening, the Great Square is high in the south to overhead, depending on your latitude in the northern hemisphere. This celestial signpost really does look like a large square pattern, with four medium-bright stars marking the corners.

You can be sure you’ve found the Great Square if you draw a line through its two westernmost (or right-hand stars) and extend that line southward to the bright star Fomalhaut in the constellation Piscis Austrinus the Southern Fish. When you look at Fomalhaut, you are looking some 90 degrees from the plane of the galactic equator.

Our Milky Way galaxy is round and flat, like a pancake. When you look toward Fomalhaut, you’re looking away from the pancake, and out the south window of the galaxy. In other words, we’re looking away from the star-packed disk of the galaxy, into extragalactic space and the realm of galaxies. The south galactic pole lies east of Fomalhaut, in the faint constellation Sculptor.

Don’t mistake the planet Jupiter (outside of our sky chart) for Fomalhaut. Jupiter, the brightest celestial point of light in the evening sky, outshines Fomalhaut by leaps and bounds. Fomalhaut is that solitary star about 25 degrees (over two fist-widths) to the lower left of Jupiter.

Written by Bruce McClure

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