What it looks like
Serpens is unique among the 88 constellations in being divided into two separate pieces. Serpens Caput (the Head) lies west of Ophiuchus, and Serpens Cauda (the Tail) lies east, with the body of the serpent-bearer between them. Its brightest star, Unukalhai, sits in the head, and the tail contains the famous Eagle Nebula (M16), home of the Pillars of Creation.
Brightest stars
Serpens has one reasonably bright star, Unukalhai, and several third-magnitude stars across both halves.
| Star | Magnitude | Distance | Meaning |
|---|---|---|---|
| Unukalhai (α Serpentis) | +2.63 | 74 ly | Neck of the Serpent |
| Eta Serpentis | +3.23 | 62 ly | — |
| Mu Serpentis | +3.53 | 157 ly | — |
| Xi Serpentis | +3.54 | 105 ly | — |
| Beta Serpentis | +3.65 | 155 ly | — |
Mythology and history
In Greek myth, Serpens is the serpent held by Ophiuchus, usually identified with the snake that taught the healer Asclepius the secret of resurrection.
The serpent of healing
Serpens is the snake held by Ophiuchus, the Serpent Bearer, who represents the healer Asclepius. According to the myth, Asclepius once saw a snake lay a herb on a dead companion and revive it, and from this he learned the secret of bringing the dead back to life. Zeus, alarmed that Asclepius might make humans immortal, struck him down with a thunderbolt — but placed him and his serpent together in the sky. The serpent wound around a staff remains the symbol of medicine to this day.
How to find it
Look for Unukalhai west of Ophiuchus (Serpens Caput) and the Eagle Nebula east of it (Serpens Cauda), on summer evenings.
- Find Ophiuchus, then look west for the Head and east for the Tail.
- The two halves are widely separated — one is in Serpens Caput, the other in Serpens Cauda.
- Best on summer evenings from both hemispheres.
Key facts
- Abbreviation
- Ser
- Genitive
- Serpentis
- Meaning
- The Serpent
- Brightest star
- Unukalhai
- Main stars
- 9
- Area rank
- 23rd
- Best visible
- July
- Declination
- 0°
- Meteor showers
- —
- Neighbours
- Hercules, Corona Borealis, Boötes, Virgo, Libra, Ophiuchus, Aquila, Scutum, Sagittarius
Deep-sky objects
Serpens contains the Eagle Nebula (M16) with its iconic Pillars of Creation, imaged by Hubble in 1995. It also contains the globular cluster M5, the open cluster M16, and the faint planetary nebula NGC 6537 — the Red Spider Nebula. The constellation lies along the Milky Way and is rich in star-forming regions.
Frequently asked questions
What does the constellation Serpens look like?
Serpens is the only constellation split into two parts — Serpens Caput (the Head) and Serpens Cauda (the Tail) — held in the hands of Ophiuchus the Serpent Bearer.
What is the brightest star in Serpens?
The brightest star in Serpens is Unukalhai, shining at around magnitude 2.63.
When is Serpens best visible?
Serpens is best seen from both hemispheres during July.
What is the story behind Serpens?
In Greek myth, Serpens is the serpent held by Ophiuchus, usually identified with the snake that taught the healer Asclepius the secret of resurrection.
Which constellations are near Serpens?
Serpens borders Hercules, Corona Borealis, Boötes, Virgo, Libra, Ophiuchus, Aquila, Scutum and Sagittarius.
Ophiuchus
Aquila