M81 and M82 in Ursa Major were discovered by J.E.Bode in December 1774; he described M82 as a "nebulous patch", about 0.75 deg away from M81, which "is very pale and of elongated shape,". Messier added it to his catalogue in February 1781.
M82 is approximately 12 million light years distant. M82 is approximately 150,000 light years from M81 and is showing the effects of a catastrophic encounter with M81 some tens of millions of years ago.
M82 is experiencing explosive star formation
and is one of the brightest infra-red sources in the sky. It is also one
of the strongest radio sources in Ursa Major