Globular Cluster M 3

M 3 is one of the largest and brightest globular star clusters. It consists of more than 500,000 stars. The cluster is located 33,900 light-years from Earth. Its apparent magnitude is 6.4m, which under clear, moonless skies away from cities allows observers with good vision to see it with the naked eye. The cluster is easy to find with binoculars even under fairly bright suburban skies (halfway from α Canum Venaticorum to the bright orange Arcturus — α Boötis). With a telescope aperture of 100 mm and higher magnification, it begins to resolve into stars (especially at the edges), and it becomes noticeable that the cluster's shape is not perfectly round. In a 150-mm telescope, it already looks like a ball of nearly a hundred stars. In a 200-mm telescope, gaps between stars in the peripheral areas become noticeable. In a 275-mm telescope, the cluster appears as a huge, "fuzzy" ball of stars.