Serpens

Serpens (the snake) is one of the 88 modern constellations, and was also one of the 48 listed by Ptolemy. Among the modern constellations it is unique in being split into two pieces, Serpens Caput (representing the head of the snake) to the west and Serpens Cauda (representing the tail) to the east. Between these two pieces lies the constellation of Ophiuchus, the serpent bearer.

Serpens
	Serpens Caput	Serpens Cauda
Abbreviation	Ser
	Ser1	Ser2
Genitive	Serpentis
Meaning in English	the Snake
	the Snake's Head	the Snake's Tail
Right ascension	15.5 h	18.3 h
Declination	10°	-5°
Visible to latitude	Between 80° and -80°
On meridian	9 p.m., June 30	9 p.m., August 5
Area  - Total	Ranked 23rd 637 sq. deg.
	429 sq.deg.	208 sq.deg.
Number of stars with apparent magnitude < 3	1
Brightest star  - Apparent magnitude	Unukalhai (α Ser) 2.7
Meteor showers
Bordering constellations	Corona Borealis Boötes Virgo Libra Ophiuchus Hercules	Aquila Ophiuchus Sagittarius Scutum

Table of contents showTocToggle("show","hide") 1 Star map 2 Notable features 3 Notable deep-sky objects 4 Mythology

Star map

Notable features

Since Serpens is regarded as being one constellation despite being split into two halves, the ordering of Bayer designations goes in order of brightness among both constellations.

Only one of the stars in Serpens is brighter than third magnitude, so the constellation is not easy to perceive. α Serpentis, named Unukalhai, is in Caput. δ Serpentis, also in Caput, is a double star only 27 light-years from Earth. θ Serpentis, in Cauda, is also double.

Stars in Caput include α, β, γ, δ, ε, ι, κ, λ, μ, π, ρ, σ, τ, χ and ω Serpentis. Stars in Cauda include ζ, η, θ, ν, ξ, and ο Serpentis.

Notable deep-sky objects

M5, a globular cluster approximately 8° southwest of α Serpentis in Caput, is among the most beautiful in the sky.

Part of the Milky Way passes through Serpens Cauda.

Mythology

Serpens is the snake being grasped by Ophiuchus, the Snake-Handler, q.v. Originally they were all one very large constellation.