The Great Andromeda Galaxy (and environs)

The outer starclouds of M31, the Great Andromeda Galaxy stretch across almost five degrees (ten times the apparent width of the Moon) in a widefield photograph. Notice the different colors of the stars in the outer spiral bands compared to the inner reaches. Younger, bluer stars predominate in the outer reaches of the galaxy; the stars closer in are older (and are also obscured and reddened by dust). Original context: 20150913.php