Summary

The image size is about 1.6 by 4.5 degrees (The full Moon is about 0.5 degrees across by comparison). Since this is an image of invisible infra-red light, blue is mapped to the WISE 3.4 & 4.6 micron channels and is dominated by star light. Green represents the WISE 12 micron channel, and red is the 22 micron channel, which are dominated by infra-red emission from warm interstellar dust.

Licensing

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A mosaic of images from WISE in the constellation of Cassiopeia. This region contains a large star forming nebula within the Milky Way Galaxy, called IC 1805 (sometimes called the Heart Nebula), a portion of which is seen at the right of the image. IC 1805 is over 6 thousand light-years from Earth. Also visible in this image are two nearby galaxies, Maffei 1 and Maffei 2. In visible light these galaxies are hidden by dust in IC 1805 and were unknown until 1968 when Paolo Maffei found them using infra-red observations. Both galaxies contain billions of stars and are located some 10 million light-years away (well outside our own Milky Way Galaxy). Maffei 1 is the bluish elliptical object in the centre of the image. It is a Lenticular type galaxy, which has a disk-like structure and a central bulge but no spiral structure or appreciable dust content. Maffei 2 (to the upper left of Maffei 1) is a Spiral type galaxy that also has a disk shape, but with a bar-like central bulge and two prominent dusty spiral arms.