The tail of comet Hyakutake (1996 B2) in from of the galaxy M101. M101, a spiral galaxy viewed face-on from our solar system, is the 101st object in a catalog of "nebulae and star clusters" produced by astronomer Charles Messier in the late 18th Century. The comet's tail is made up of illuminated dust and ionized plasma, the former pointing back along the comet's path, the latter pointing away from the sun.