Serpens, or the Serpent, is held by the Serpent Holder, Ophiuchus, and is the only constellation to consist of two separate parts - Serpens Caput (the Head) and Serpens Cauda (the Tail).
Derivation
Though the stars of this region have been seen as a serpent for thousands of years, their symbolic meaning remains uncertain. It is thought likely that the Serpent and its bearer
Ophiuchus are related to the Greek healer-god Asclepius. The Greeks believed that the serpents of Asclepius could cure diseases, and so belong a long association between serpents and
medicine that continues to our own time.
Stars
The stars of Serpens form the shape of a long writhing snake that starts near the Northern Crown, passes southward through Serpens Caput, then through the body of Ophiuchus. When the
shape emerges into Serpens Cauda, it turns northward again, and carries on to reach its end into the Milky Way. The tip of the Serpent's nose is the faint star Rho Serpentis, while the
tip of its tail is marked by the similarly faint Alya. A number of the stars that form part of the serpent's body actually belong to the constellation Ophiuchus. Yed Prior, Yed
Posterior, Upsilon Ophiuchi, Zeta Ophiuchi and Sabik are all Ophiuchan stars that lie along the star-snake's body.
Though its shape is well-defined, Serpens is lacking in bright stars. The brightest is Unuk Élhaia (the 'serpent's neck') an orange giant about seventy light years away, with a magnitude of +2.6. Beta Serpentis, the next brightest star, is more than a magnitude fainter at +3.7.
Star Clusters and Nebulae
Serpens contains no deep-sky objects that are visible to the naked eye, but it is not without points of interest. One of these is the very distant Globular Cluster M5, in the southern
parts of Serpens Caput. About 25,000 light years away, this gigantic ball of stars is close to the Nucleus of the Milky Way.
Stars In Serpens Caput
M5 (NGC5904)
M5 (NGC5904) is a spectacular globular cluster in the constellation of Serpens Caput (head), with a size of about 13 arc minutes. There is a star "5 Serpentis" with magnitude of 5 just 30' SE of M5, the star is a good mark to search the cluster with telescopes. You can see the star at the lower left hand side in this photograph. The cluster has nearly similar size with M13 in Hercules; it's one of representative globular clusters in summer sky. M5 is a globular cluster with the largest real size of 130 light years in Messier's catalogue. Distance is 27 thousand light years away.
M16 (NGC6633)
So small binoculars are most suitable for appreciating those clusters. Because background Milky Way is fairly striking, good conditioned skies might be needed to enjoy fine and beautiful individual member stars in those clusters.
Galaxies In Serpent Caput
NGC 5921
A small-bared galaxy in center of Serpent Caput is NGC5921. The galaxy is positioned about 3 degrees north of M5, a striking and bright globular. NGC5921 has a diameter of about 5 arc minutes, two arms are coiled up loosely from a dimmed central nucleus.
