Messier 12 or M 12 (also designated NGC 6218) is a w:globular cluster in the w:constellation of w:Ophiuchus. It was discovered by w:Charles Messier on w:May 30, w:1764.

Messier 12, from 2MASS
Observation data (J2000 epoch)
Right ascension16h 47m 14.52s[1]
Declination-01° 56′ 52.1″[1]
Distance16.0 kly (4.9 kpc)
Apparent magnitude (V)+7.68[1]
Apparent dimensions (V)16′.0
Physical characteristics
Masskg ( M)
Radius37.2 ly[2]
Other designationsNGC 6218[1]

Located roughly 3° in the sky from the cluster M10, M12 is about 16,000 w:light-years from Earth and has a spatial diameter of about 75 light-years. The brightest stars of M12 are of 12th magnitude. It is rather loosely packed for a globular and was once thought to be a tightly concentrated w:open cluster. Thirteen w:variable stars have been recorded in this cluster.

A study published in w:2006 concluded that this cluster has an unusually low number of low mass stars. The authors surmise that they were stripped from the cluster by the gravitational influence of the w:Milky Way.[1]

External links


  1. a b c d "SIMBAD Astronomical Database". Results for NGC 6218. Retrieved 2006-11-15.
  2. distance × sin( diameter_angle / 2 ) = 37.2 ly. radius