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Use Cassiopeia to find Andromeda galaxy

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September 17, 2018

But what if 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.

View larger. Anthony Lynch Photography provided this beautiful shot of a Perseid meteor and the Andromeda galaxy. Thank you, Anthony!

Cassiopeia appears low in the northeast sky at nightfall and early evening, then swings upward as evening deepens into late night. In the wee hours after midnight, 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.

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. 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.

Andromeda_galaxy_from_Perseus_Cattleya_Flores_Viray — View larger. | Many people find the Andromeda galaxy from the two streams of stars extending from the Great Square (they are the constellation Andromeda). Or they find the galaxy via the constellation Cassiopeia. This photo via EarthSky Facebook friend Cattleya Flores Viray.

cass_andro_galaxy_600 — View larger. | 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: Some prefer the constellation Cassiopedia – which is easy to find, shaped like an M or W – as a jumping off point for locating the Andromeda galaxy.

More about M31: Great galaxy in Andromeda

Use the Great Square of Pegasus to find the Andromeda galaxy

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September 17, 2018

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Bruce McClure

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About the Author:

Bruce McClure served as lead writer for EarthSky's popular Tonight pages from 2004 to 2021, when he opted for a much-deserved retirement. He's a sundial aficionado, whose love for the heavens has taken him to Lake Titicaca in Bolivia and sailing in the North Atlantic, where he earned his celestial navigation certificate through the School of Ocean Sailing and Navigation. He also wrote and hosted public astronomy programs and planetarium programs in and around his home in upstate New York.