NASA’s Wide-field Infrared Survey Explorer (WISE) mapped out the entire sky in the far-infrared for about a year. Since it was a survey instrument, it didn't take pictures per se, instead counting infrared photons, noting their position, time, and energy. This allows astronomers to make a mosaic image of any size... so they created this astonishing map of the constellations Cassiopeia (the Queen) and Cepheus (the king), covering over 1000 square degrees of sky! For comparison, the full Moon is about 1/5 of a square degree: this map covers the equivalent of 5000 full Moons!
There is no way I can convey the sheer depth and breadth of this image in the 610 pixel width of this blog, so you should download the crazy huge 70 Mb 13530 x 4609 pixel version. You can then sweep over the dust, gas, stars, cavities, shells, supernova remnants, and everything else littering this picture. It's breath-taking. To give you a hand, red colors are from very cool dust, green tends to come from complex organic molecules, and blue from warmer dust and gas.
WISE shut its eye in February 2011, but the data it complied will keep astronomers busy for many years to come.
Credit: Image Credit: NASA/JPL-Caltech/WISE Team