- Messier 12 or M 12 (also designated NGC 6218) is a globular cluster in the constellation of Ophiuchus. It was discovered by the French astronomer Charles Messier on May 30, 1764, who described it as a “nebula without stars”. In dark conditions this cluster can be faintly seen with a pair of binoculars. Resolving the stellar components requires a telescope with an aperture of 8 in (20 cm) or greater. In a 10 in (25 cm) scope, the granular core shows a diameter of 3′ (arcminutes) surrounded by a 10′ halo of stars.
- Ophiuchus (Wikipedia)
Ophiuchus (/ˌɒfiˈjuːkəs/) is a large constellation straddling the celestial equator. Its name comes from the Ancient Greek ὀφιοῦχος (ophioûkhos), meaning “serpent-bearer”, and it is commonly represented as a man grasping a snake. The serpent is represented by the constellation Serpens. Ophiuchus was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. An old alternative name for the constellation was Serpentarius (/ˌsɜːrpənˈtɛəriəs/).