M3 Globular Cluster Messier 3 Post author:ScottH Post published:June 11, 2015 Post category:Star Clusters Messier 3 is a globular cluster located in the constellation Canes Venatici. Charles Messier discovered this star cluster in 1764. This globular cluster has an estimated 500,000 stars. It was imaged with the Astro-Physics AP160EDF refractor. You Might Also Like Messier 2 September 14, 2014 Messier 12 May 23, 2014 Messier 23 May 26, 2017