Ursa Major Moving Cluster

The Ursa Major Moving Cluster is a loose group of stars, widely scattered about the sky, with similar space velocities (about 14 kilometers per second in the direction of eastern Sagittarius), that includes five of the seven major members of the Big DipperMerak (Beta), Phad (Gamma), Megrez (Delta), Alioth (Epsilon), and Mizar (Zeta) – as well as Alphekka (Alpha Coronae Borealis) and Sirius (Alpha Canis Majoris). With its center located about 75 light-years from us, about half the distance of the Hyades, it is the nearest star cluster to the Sun. Its proximity and its size (some 30 light-years long by 18 light-years wide) mean that it covers an enormous portion of the sky.