Messier 5 or M5 (also designated NGC 5904) is a globular cluster in the constellation Serpens. It was discovered by Gottfried Kirch in 1702. Spanning 165 light-years in diameter, M5 is one of the largest known globular clusters.
At 13 billion years old, M5 is also one of the eldest globular clusters in the Milky Way Galaxy. Its distance is about 24,500 light-years from Earth, and it contains more than 100,000 stars, as many as 500,000 according to some estimates.