This image from NASA's Wide-field Infrared Survey Explorer, or WISE, highlights the dust that speckles the Andromeda galaxy's spiral arms. It shows light seen by the longest-wavelength infrared detectors on WISE (12-micron light has been color coded orange, and 22-micron light, red).
The hot dust, which is being heated by newborn stars, traces the spidery arms all the way to the center of the galaxy. Telltale signs of young stars can also be seen in the centers of Andromeda's smaller companion galaxies, M32 and M110.
Andromeda, also called M31, is 2.5 million light-years away, and is the nearest large neighbor to our Milky Way galaxy.
NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate, Washington. The mission's principal investigator, Edward Wright, is at UCLA. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.