M3 - Globular Cluster

In the constellation of Canes Venatici. Between the constellations of Canes Venatici, Boötes and Coma Berenices lies one of the brightest clusters in the sky: M3, discovered by Charles Messier in 1764. It sits fairly far from bright stars, but can be easily found with an amateur instrument starting from β Comae Berenices, a magnitude-4 star about 7° west of the cluster; a second reference point is Arcturus, a very bright orange star further south. The cluster is made up of about 500,000 stars and lies roughly 33,900 light-years away. It has an apparent magnitude of 6.2, making it visible to the naked eye under dark skies. Some 212 variable stars have been found within it, more than in any other globular cluster in our galaxy. It is thought to be about 10 billion years old.