Sky ArchiveTonight

Cassiopeia points to the Andromeda galaxy

Star chart of constellations Cassiopeia and Andromeda with labeled Andromeda galaxy between them.
Most people use the M- or W-shaped constellation Cassiopeia to find the Andromeda galaxy. See how the star Schedar points to the galaxy?

Tonight, if you have a dark sky, try star-hopping to the Andromeda galaxy from the constellation Cassiopeia the Queen. If your sky is truly dark, you might even spot this hazy patch of light with no optical aid, as the ancient stargazers did before the days of light pollution.

What if your sky is more lit up, and you can’t find the Andromeda galaxy with the eyes alone? Some stargazers use binoculars and star-hop to the Andromeda galaxy via this W-shaped constellation.

Cassiopeia appears in the northeast sky at nightfall and early evening, then swings upward as evening deepens into late night. In the wee hours before dawn, Cassiopeia is found high over Polaris, the North Star. Note that one half of the W is more deeply notched than the other half. This deeper V is your “arrow” in the sky, pointing to the Andromeda galaxy.

The Andromeda galaxy is the nearest large spiral galaxy to our Milky Way. It’s about 2.5 million light-years away, teeming with hundreds of billions of stars.

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Fuzzy bright oblong with bright center at an angle against a star field.
View larger. | Josh Blash shot this in 2014. He wrote, “M31, the Andromeda Galaxy. I used 29 frames shot at 90mm and tracked for 60 seconds each, then stacked them using the DeepSkyStacker software.” See more photos by Josh Blash on Facebook.
Star chart of constellation Cassiopeia and arrow pointing to Andromeda Galaxy below it.
Draw an imaginary line from the star Kappa Cassiopeiae (abbreviated Kappa) through the star Schedar, then go about 3 times the Kappa-Schedar distance to locate the Andromeda galaxy (Messier 31).

Bottom line: You can find the Andromeda galaxy using the constellation Cassiopeia as a guide. Remember, on a dark night, this galaxy looks like a faint smudge of light. Once you’ve found it with the unaided eye or binoculars, try with a telescope if you have one.

Use the Great Square of Pegasus to find the Andromeda galaxy

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August 18, 2020
Sky Archive

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Bruce McClure

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