 messier 108 (also known as ngc 3556) is a barred spiral galaxy in the constellation ursa major. it was discovered by pierre mÃ©chain in 1781 or 1782.  from the perspective of the earth, this galaxy is seen almost edge-on. this galaxy is an isolated member of the ursa major cluster of galaxies in the virgo supercluster. it has a morphological classification of type sbbc in the de vaucouleurs system, which means it is a barred spiral galaxy with somewhat loosely wound arms. the maximum angular size of the galaxy in the optical band is 11â².1 Ã 4â².6, and it is inclined 75Â° to the line of sight.  thumb|left|240px|amateur image of m108 this galaxy has an estimated mass of 125 billion times the mass of the sun and includes about 290 Â± 80 globular clusters.  examination of the distribution of neutral hydrogen in this galaxy shows shells of expanding gas extending for several kil
Astronomical_objects_discovered_in_1781 Barred_spiral_galaxies Messier_objects NGC_objects Objects_within_100_Mly_of_Earth PGC_objects Spiral_galaxies UGC_objects Ursa_Major_(constellation)