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The Infrared Sky

This is a panoramic view of the most of the sky (rendered in an Aitoff projection). This view is not an actual image of the sky; it has been generated by computer from star counts in the 2MASS point source database. Each color represents the local density of stars seen in each of three infrared wavelengths: 1.25 microns rendered as blue, 1.65 microns rendered as green, and 2.17 microns rendered as red. . Almost 100 million stars appear here, going down to Ks magnitudes as faint as 13.5.

Most prominent in the image is the high density of stars along the disk of our Milky Way Galaxy, peaking up at the bulge at its very center. The plane is cut by dark dust lanes and clouds. In visible light, the dust lanes are much more prominent, blocking our view of a substantial part of the Galactic Plane; here, only the very densest dust clouds remain, obscuring the stars and reducing the star counts. 

The two companion galaxies to the Milky Way, the Large and Small Magellanic Clouds, are very obvious in the lower half of this image. The large number of stars they contain cause them to show up with high contrast in these star count maps. Note in particular the prominent bar and incipient spiral structure of the Large Cloud which can be difficult to discern in direct images of the region.

The star-like objects in this map are actually globular clusters that appear "bright" because they have so many stars in very compact areas. Most prominent is the globular cluster 47 Tucanae, just to the left of the Small Magellanic cloud. Another striking feature is the "finger" of stars cutting almost north-south through the lower left side of the Galactic bulge. These stars belong to the dwarf Sagittarius galaxy, another satellite of the Milky Way that is in the process of merging with it.

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