M10 (also known NGC 6254) is a globular cluster in the constellation Ophiuchus. It was discovered by Charles Messier on May 29, 1764, it was described as a “Nebula without stars.”

M10 has an apparent diameter of some 20′, about 2/3 the apparent diameter of the moon, which translates to a spatial diameter of 83 light-years at its estimated distance of 14,300 light-years. Viewed through medium sized telescopes it appears about half that size (8′ to 9′), as its brighter core is only 35 light-years across. 

Images by Andrew Wilson