The object was discovered by Charles Messier on May 29, 1764, who cataloged it as number 10 in his list. He described it as a "nebula without stars", but later study revealed it as a globular cluster of thousands of stars.
M10 has an apparent diameter of some 20 arcminutes, about two-thirds of the apparent diameter of the Moon. Viewed through medium-sized telescopes it appears about half that size (8' to 9'), as its bright core is only 35 light-years across. M10 has a spatial diameter of 83 light-years and is estimated to be 14,300 light-years away from Earth. Four variable stars have been discovered in this cluster.