... 2002 June 20 . Bright Galaxy M81 . ... Explanation: Big and beautiful spiral galaxy M81 , in the northern constellation Ursa Major , is one of the brightest galaxies visible in the skies of planet Earth. This superbly detailed view reveals its bright nucleus, grand spiral arms and sweeping cosmic dust lanes with a scale comparable to the Milky Way . ... The errant dust lane may be the lingering result of a close encounter between M81 and its smaller companion galaxy, M82 . ... About APOD | ...