Forming a most conspicuous physical pair with its neighbor, M81 (THE showpiece galaxies for many Northern hemispherers), this galaxy is the prototype of an irregular of the second type, i.e. a "disk" irregular. Its core seems to have suffered dramatically from a semi-recent close encounter with M81, being in a heavy starburst and displaying conspicuous dark lanes. This turbulent explosive gas flow is also a strong source of radio noise, discovered by Henbury Brown in 1953.
Recently, over 100 freshly-formed (young) globular clusters have been discovered with the Hubble Space Telescope. Their formation is probably another effect triggered by the encounter with M81. It was estimated that the most recent tidal encounter occurred between about 50 and several 100 million years ago.
As a member of the M81 group , M82 is 12 million light years distant.
M82 was discovered on December 31, 1774 by Johann Elert Bode together with M81; he described it as a "nebulous patch", about 0.75 deg away from M81, which "is very pale and of elongated shape," and cataloged it as No. 18 in his catalog. Pierre Méchain independently rediscovered both galaxies as nebulous patches in August 1779 and reported them to Charles Messier, who added them to his catalog after his position measurement on February 9, 1781.
William Parsons, the Third Earl of Rosse was the first to remark on the dark dust lanes and patches visible in the central part of M82.