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Saturday, April 18, 2015

EarthSky Tonight—Sept. 29, Star-hop from Great Square to Andromeda galaxy

Courtesy of EarthSky
A Clear Voice for Science

The Great Square of Pegasus is a great jumping off point for finding the Andromeda galaxy, otherwise known as M31. The Great Square sparkles over your eastern horizon at early evening, then travels westward across the sky throughout the night. For some idea of the Great Square’s size, extend your hand an arm length from your eye. You will see that any two Great Square stars are farther apart than the width of your hand.

As seen from mid-northern latitudes, the Square of Pegasus looks like a baseball diamond whenever it resides in the eastern sky. Imagine the farthest star to the left – Alpheratz – as the third-base star. A line drawn from the first-base star through Alpheratz points in the general direction of the Andromeda galaxy.

If it is dark enough, you will see two streamers of stars flying to the north (or left) of the star Alpheratz. To me, this grouping of stars looks like a bugle or a cornucopia. Along the bottom streamer, star-hop from Alpheratz to the star Mirach. Draw a line from Mirach through the upper streamer star, and go twice the distance. You have just located the Andromeda galaxy!

If you cannot see this fuzzy patch of light with the unaided eye, maybe your sky is not dark enough. Try binoculars! If you can find the Great Square of Pegasus, then you can star-hop to the Andromeda galaxy!

Andromeda galaxy, closest spiral to Milky Way

Written by Bruce McClure

Astronomy Picture of the Day from NASA/JPL

CHANDRA Photo Album

U.S. Naval Observator Astronomical Information center

Universe Today

StarDate Online

Sky and Telescope

National Geographic

Space Com

Simostronomy Blog

Amazing Space

The York County Astronomical Society

Scope City

James S McDonnell Planetarium

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