The galaxy known as Andromeda is situated some 2.5 million light-years from our location, riding like a majestic counterweight to the Milky Way (which it is believed to resemble) on the other end of the Local Group.

This spectacular infra-red photo was taken by the Spitzer Space Telescope, a composite of over 3,000 individual frames. In this image, interstellar gas appears red, while older stars show up in blue. Young stars located in the galaxy's spiral arms are clear in the visible light spectrum, but when the infra-red filter is added, trails of dust lead back toward the core.

The purpose behind this image was to  explore Andromeda's infra-red brightness and determine the nature of its stellar population. Although as a "spiral"-type galaxy, Andromeda - with around one trillion stars - is well over twice the size of the Milky Way.