M81 and M82 are a pair of galaxies in the constellation Ursa Major. The pair is located approximately 10 degrees northwest of the “Big Dipper” pointer star Dubhe (Alpha Ursae Majoris). The apparent separation of the galaxies is 31 arc-minutes but at a distance of 12 million light-years, their actual distances from each other are 150,000 light years. They are the largest members of the M81 Group, a physical association of 34 galaxies.
M81 – Bode´s Galaxy
Messier 81 or M81 (also designated NGC 3031) is a spiral galaxy. It has an apparent visual magnitude of 6.9 and its angular diameter is 21×10 arc-minutes. M81 located at an estimated distance of 12 million light years.
Although included in the Messier Catalog, M81 was actually discovered by J. E. Bode in 1774, the diameter is 92,000 light years and estimated mass is 50 billion solar masses.
M82 – Cigar Galaxy
Messier 82 or M82 (also designated NGC 3034) is a starburst galaxy in the constellation Ursa Major. It has an apparent visual magnitude of 8.4 and its angular diameter is 9×4 arc-minutes. M82 lies at an estimated distance of 12 million light years. The Equinox 2000 coordinates are RA= 9h 55.8m, Dec= +69° 41´.
Together with M81, this peculiar galaxy was actually discovered by J. E. Bode in 1774. M82 has an irregular, distorted disk due to the gravitational interaction of its larger neighbor M81. It is known as a starburst galaxy since it is the site of intense star-forming activity.