Messier 10 by Hubble Space Telescope; 3.5′ view
|Observation data (J2000 epoch)|
|Right ascension||16h 57m 08.99s|
|Declination||-04° 05′ 57.6″|
|Distance||14.3 kly (4.4 kpc)|
|Apparent magnitude (V)||6.4|
|Apparent dimensions (V)||20′.0|
|Mass||kg ( M)|
|Radius||41.6 ly |
|Other designations||NGC 6254|
The object was discovered by w:Charles Messier on w:May 29 w:1764, who cataloged it as number 10 in his list. He described it as a "w:nebula without stars", but later study revealed it as a globular cluster of thousands of stars.
M10 has an apparent diameter of some 20 w:arcminutes, about two-thirds of the w:apparent diameter of the w:Moon. Viewed through medium-sized w:telescopes it appears about half that size (8' to 9'), as its bright core is only 35 light-years across. M10 has a spatial w:diameter of 83 w:light-years and is estimated to be 14,300 light-years away from Earth. Four w:variable stars have been discovered in this cluster.