What's lighting up the Cigar Galaxy? M82, as this irregular galaxy is also known, was stirred up by a recent pass near large spiral galaxy M81. This doesn't fully explain the source of the red-glowing outwardly expanding gas, however.

Not all galaxies have spiral structure like our Milky Way. Many have smooth elliptical shapes, but also many have irregular shapes such as the bright sky object M82, the 82nd object on Messier's list.

Something strange happened to this galaxy, but what? M82 is a nearby galaxy in the group of galaxies dominated by itself, M81, and NGC 3077. M82 is thought by some to be limping away from a close encounter with M81.