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Peer out our galaxy’s south window


Tonight for November 15, 2015

Tonight, or any clear November evening, try using the Great Square of Pegasus to star-hop your way to a view out our galaxy’s south window. In other words, you’ll be looking away from the flat plane of our Milky Way – where most of our galaxy’s stars reside – and toward intergalactic space. You can do this no matter what part of Earth you’re standing on, by the way.

From the Northern Hemisphere: The Great Square of Pegasus appears high in the south to overhead each November, by about 8 p.m. This large asterism really does look like a large square pattern, with four medium-bright stars marking the corners. Draw a line through the Great Square’s two westernmost (or right-hand stars), and extend that line southward to land on the bright star Fomalhaut in the constellation Piscis Austrinus the Southern Fish.

From the Southern Hemisphere: Follow the directions above, but – instead of looking southward to overhead for the Great Square – you’ll be looking low in the north. You’ll still draw your line southward, but, in your sky – starting at the Great Square – that means you’ll draw the line upwards to Fomalhaut. Just take the chart at the top of this post, and turn it upside-down!

Why find Fomalhaut? When you look at this star – sometimes called the Loneliest Star – you are looking some 90 degrees from the plane of our galaxy’s 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.

Want the exact location of the south galactic pole? It lies east of Fomalhaut, in the faint constellation Sculptor.

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The south galactic pole lies in the direction of the constellation Sculptor.

Bottom line: Tonight, try using the Great Square of Pegasus to find the star Fomalhaut. Once you’ve found Fomalhaut, you’re on your way to visualizing looking out the south window of our Milky Way galaxy.

Easily locate stars and constellations during any day and time with EarthSky’s Planisphere.

Astronomy events, star parties, festivals, workshops for September-December, 2015

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