The Infrared Face of the Andromeda Galaxy

This image from NASA's retired Spitzer Space Telescope highlights the stars and dust clouds in the Andromeda galaxy. One of Earth's nearest galactic neighbors, Andromeda spans a swath of sky nearly 3.8 degrees across, which is close to the width of eight full Moons lined up side by side. The area around the galaxy includes data from NASA's Wide-field Infrared Survey Explorer (WISE). Spitzer observed infrared light, a range of wavelengths longer than what human eyes can detect. In this image, starlight glows blue and cyan (representing infrared wavelengths of 3.6 and 4.5 microns). Dust dominates the galaxy in red (8 microns). The longest wavelength detected by Spitzer (24 microns) gives an indication of the dust's temperature and is represented in green; it combines with the red to create orange and yellow, indicating regions where stars are forming. https://photojournal.jpl.nasa.gov/catalog/PIA26276