The snake is the only constellation that is split into two parts. The Snake‘s Head (Serpens Caput) is located west of Ophiuchus and away from the galactic plane. Here we can see deep into space, and with a larger telescope many faint galaxies are accessible. The Tail of the Snake (Serpens Cauda) is located east of Ophiuchus in the galactic plane. Because of the dust clouds of the Great Rift we can only see a few deep-sky objects here as most are hidden by dust.
The actual Head of the Snake is a small group formed by the stars β (3.6m), γ (3,8m), κ (4.1m) and ι (4.5m). The stars have all different distances, so they only form an asterism and no open cluster. The snake‘s head has a diameter of 5.5°.
M 5 is one of the six brightest globular clusters, but you need at least 25x magnification to resolve individual stars. In 1764, Messier was sure that the nebula „contains no star“. Also the discoverer Gottfried Kirch saw only a patch of light in 1702. No sooner than 1791, William Herschel saw 200 stars at the center of M 5. With 5.7m and a diameter of 20 arc minutes, M 5 appears in every binocular as a slightly flattened patch of light. M 5 is 26,000 light-years away and contains about 500,000 stars in an area with a diameter of 150 light-years. Its stars have luminosities between the eleventh and fifteenth magnitude, viewed from this distance, our Sun would shine no brighter than 19.4m, which gives an impression of the luminosity of the stars.
IC 4756 is one of the oldest known star clusters. It was probably formed a billion years ago, so no high-luminosity blue stars remain. About 80 stars are spread over an area of almost 1° diameter – a beautiful sight against the background of the Milky Way. Its brightest stars reach seventh magnitude, the fainter stars in its center are framed by a nice trapezoid of 7m stars. Within this 20 light-years wide and 1,200 light-years distant star cluster there are many smaller groups of stars.