Tonight … November 18, 2014. The Andromeda galaxy is out all night long at this time of year, and last week we told you how to use the constellation Cassiopeia to find it. There’s another way to find the Andromeda galaxy, though; you can also locate it using the Great Square of Pegasus. This post is about how to do that. Plus we wanted to point to a close pairing of the moon and star Spica in the predawn sky on Wednesday, November 19.
Moon and Spica first! The chart below shows how they’ll look as seen in Wednesday morning’s predawn sky. Although their orientation will change depending on your latitude, the moon and Spica – which is the constellation Virgo’s brightest star – can be seen across Earth now.
Okay, back to the Andromeda galaxy. You can see it at this time of year … simply by looking eastward at nightfall. That’s assuming you’re looking into a dark, moon-free sky that isn’t drowned by city lights. And it’s also assuming you’re in the Northern Hemisphere. The Andromeda galaxy is located rather far to the north on the sky’s dome, and can’t be seen as well (or at all) from the Southern Hemisphere. From Northern Hemisphere latitudes, by mid-evening, this galaxy will climb almost straight overhead, so you might want to enjoy the comfort of a reclining lawn chair for viewing this deep-sky treasure.
This neighboring spiral galaxy appears in our sky as a large hazy patch – bigger than a full moon. It’s very noticeable in a star-filled sky, far from city lights, on a night when the moon is down.
Can’t find it? Look at the chart at the top of this post. One way to find the galaxy is by finding the Great Square in the constellation Pegasus. The Great Square consists of a large square pattern of stars in the east at nightfall. By mid-evening, the Great Square swings way up high in your southern sky.
Extending from the Square, you’ll find two graceful streams of stars – another constellation, Andromeda. I learned to find the Andromeda galaxy by “star-hopping” from the star Alpheratz in Great Square to the two stars marked here – first Mirach, then Mu Andromedae.
An imaginary line drawn through these two stars points to the Andromeda galaxy. If you can’t see the Andromeda galaxy with the unaided eye, try binoculars.
Bottom line: Here’s how to use the Great Square in the constellation Pegasus to find the Andromeda galaxy. Also, be sure to see the waning crescent moon and star Spica in the east before dawn on Wednesday, November 19, 2014.