Globular star clusters are a symmetrical collection of ancient stars (up to a million such stars). Recent estimates indicate that about 150 globulars exist in the Milky Way with only three being readily visible to the naked eye (the Andromeda Galaxy has been estimated to contain approximately 500 globular clusters). Since most of the globular clusters are more common in the southern hemisphere, scientists have deduced that our sun must lie away from the galactic core of the Milky Way. One of the most beautiful such globular clusters is M13 in Hercules.

Note: The stunning globular cluster M3 in Canes Venatici was first observed and described by Charles Messier in 1764. It has been estimated to lie 33,900 light-years away and to have an apparent diameter of approximately 180 light years. The cluster is comprised of approximately 500,000 stars which include members as bright as magnitude 12.7. Estimates as to its age vary dramatically and range from 5 billion to 26 billion years which, either way, make it older than our solar system. M3 is particularly unique due to the fact that it has been found to contain the most variable stars of any globular cluster in our galaxy. Its classification reveals its very dense core.

As with all globular clusters, M3 is best observed using narrow-field high-power views where, for example, the white and hot member stars provide a stunning view and similar to a large collection of diamonds against the background sky. The cluster lies between Bootes and Coma Verenice and is approximately 12 degrees north of Arcturus (mag 0.16). M3 is best observed during winter when it is directly overhead a few hours after midnight.

Note: For an excellent article on globular clusters, see S&T (Mar/2006: 30-36).