Hot and cold Andromeda
M31, also known as the Andromeda galaxy, is one of the closest galaxies to our own at “only” 2.5 million light-years away. Experts believe Andromeda holds about a trillion stars and spans over 200,000 light-years. This image of our neighbor, taken in infrared, shows the “cool clouds of start birth” lining the galaxy. As NASA writes, “Massive young stars are heating blankets of dust that surround them, causing them to glow in the longer-wavelength infrared light.” This infrared light is color-coded as orange. The blue images are from X-rays showing supernova explosions and massive dead starts.