The Wide-field Infrared Survey Explorer was turned off a few months ago, but the science it did lives on. NASA just released a gallery of nine spiral galaxy images taken by WISE, and they're lovely:
[Click to galactinate.] Several of my favorite big, grand design spirals are there, like M51, M81, and M83. Note that since WISE only sees infrared light, these are false color images; the colors used are blue for 3.4 micron IR light, cyan for 4.6 microns, green for 12 microns, and red for 22 microns. The reddest light a human eye can see is very roughly 0.75 microns, to give you a comparison. In the images, star-forming regions are yellowish and/or pink, dust (in the form of long-chain organic molecules called polycyclic aromatic hydrocarbons) is green, and old stars are blue. While looking over the images, I actually recognized the name of the one in the ...
