M3 - CANES VENATICI GLOBULAR

Messier 3 is a stunning globular cluster in the constellation Canes Venatici, often considered one of the finest globular clusters in the northern sky. Located approximately 33,900 light-years from Earth, it contains an estimated 500,000 stars and spans about 180 light-years in diameter. M3 was the first object discovered by Charles Messier himself in 1764, which ultimately inspired him to create his famous catalog of nebulous objects. The cluster shines at an apparent magnitude of 6.2, placing it just at the edge of naked-eye visibility under exceptionally dark skies. M3 is particularly notable among astronomers for its extraordinarily large population of variable stars. Over 270 variable stars have been identified within the cluster, the most of any known globular cluster, with the majority being RR Lyrae type pulsating stars. These variables have been invaluable for calibrating the cosmic distance ladder. Through a small telescope, M3 appears as a bright, round fuzzy ball, but telescopes of 6 inches or more begin to resolve the outer halo into a sparkling field of individual stars. The core remains dense and unresolved in all but the largest amateur instruments. At an estimated age of about 11.4 billion years, M3 is slightly younger than many globular clusters, and its stars show a range of metallicities that have provided important clues about stellar evolution.

Contains roughly 500,000 stars spanning 180 light-years in diameter at a distance of approximately 33,900 light-years.