Ursa Major Cluster

Not to be confused with Ursa Major Moving Group.

The Ursa Major Cluster (Ursa Major I Cluster, UMa I ClG) is a spiral-rich galaxy cluster of the Virgo Supercluster.

Some of its largest members are NGC 3631, NGC 3953, M109 on North (M109 Group) and NGC 3726, NGC 3938, NGC 4051 on South.^[1]

The Ursa Major cluster is located at a distance of 18.6 megaparsecs (60 million light-years) and contains about 30% of the light emitted but only 5% of the mass of the nearby Virgo Cluster.^[1]

The Ursa Major Cluster is part of the Ursa Major Cloud,^[2][3][4] a dense filament of about approximately 580 galaxies,^[3][5] that was identified and described in 1987 by astronomer Brent Tully with colleague Richard Fisher in his book The Nearby Galaxies Atlas, as Cloud 12, and contains many other groups of galaxies besides the Ursa Major Cluster.^[2] The Ursa Major Cloud is part of a larger fillament, emanating from the Centaurus Cluster through the Virgo Cluster and continues through the Ursa Major Cluster all the way to the Perseus–Pisces Supercluster, that is known as the Virgo Strand or Centaurus–Virgo–PP Filament.^[6][7]