Universe Guide

Serpens, The Serpents Constellation

Serpens Constellation Star Map

Serpens (Pronounciation:Sir-pens, Abbrev:Ser, Latin:Serpentis) is a constellation, one of 88 constellations that the night sky is divided into. The sky is not divided up equally between the constellations. Serpens takes up 636.928 sq. degrees of the night sky which equates to 1.54% of the night sky. Serpens is the 23rd largest in terms of size in the night sky.

The constellation name means The Serpents . The constellation is one of the original constellations that was devised by the Ancient Greco-Egyptian astronomer Ptolemy who lived between 90 A.D. and 168 A.D.

There are 11 stars that make up the main constellation. The hipparcos satellite scanned and detailed 1539 stars. There are 65 stars that can be seen with the naked eye in the constellation on a very clear night sky.

Serpens is not a member of the Zodiac group of twelve constellations that appear when the Sun sets. Serpens is an equatorial constellation that can be seen by countries nearest the Equator.

There are 17 Extrasolar Planets (Exoplanets) in this constellation that are detailed on this site. There is a dedicated page for exoplanets in Serpens.

There are 2 deep space objects that were identified by Charles Messier in this constellation. There are no non-Messier deep space objects in this constellation that are covered at present on this site.

The image at the top right of this page was generated using Night Vision, a free to use and download application by Brian Simspon.

Distance to Serpens

You can't just go to one location and arrive at the constellation because the constellation is made up of stars at different locations and different distances. The nearest main star in the constellation is at a distance of 36.71 light years and the furthest main star is a distance of 381.92 light years. The average distance to the main stars is 147.85 light years.

Serpens Star Facts

The caveat of these stars are that they are catalogued on this site. If you know of a star that is nearer or further then do let me know in the comments and I'll add it to the site. The stars mentioned are from the Hipparcos catalogue or have been added because of their special status.

HIP 88574, Serpens's Nearest Star

The nearest star to Earth is HIP 88574 which is roughly about 25.31 Light Years from the Earth. The nearest star to the Earth with an exoplanet is HD 168443 which is about 122.07 Light Years.

HIP 90910, Serpens's Furthest Star

The furthest star that is located in the constellation is HIP 90910 and it is 326163.3 light years away from the Sun. The furthest figure is derived from either the 1997 or 2007 Hipparcos star catalogue parallax figure and it has been known to produce distances that are wrong.

Unukalhai, Brightest Star in Serpens

The brightest star in Serpens is Unukalhai and is located about 143.84 light years from the Sun. The star has a apparent magnitude of 2.63 but an absolute magnitude of 0.85 when the star is viewed from a distance of 10 Parsecs or 32.6 Light Years. The star is recognised as being the brightest in the constellation as it has the Bayer status of Alpha.

Tau6 Serpentis, Serpens's Dimmest Visible Star

The dimmest star that can be seen in Serpens with the naked eye is Tau6 Serpentis. The dim star has an apparent magnitude of 6. The dimmest star that a person is able to see with their naked eye is 6.0 magnitude based on the table in the reference. Ref: University of Michigan.

SDSS J155720.77+091624.6

SDSS J155720.77+091624.6 is a mouthful to say and is usually just referred to as SDSS 1577+0916 which is still a mouthful but its shorter. What is remarkable about this star is that its a binary star system with a white dwarf and a brown dwarf star orbiting it. There is a strong possibility that there is also a planet in orbit round the stars.

How to Find and View Serpens in the Night Sky

Northern Hemisphere

The head of the Serpens will appear from about April on the NE -> E horizon. It will appear earlier in the previous month but you will need to stay up later. It will fall back out of site in October in a westerly direction. During the time that it is up, you can see the Kappa Serpentids meteor shower. The main bad news is that you will need to get up early to see it.

Southern Hemisphere

Serpens Caput can be seen in the night sky from May with its head on the horizon in a near easterly direction. It will rise over the coming months and then eventually head back down in October. Serpens Cauda will only just appear in May and disappear below the horizon in November.

Serpens Mythology

The Serpents although two separate constellations are usually referred to as one. The Serpens Cauda is the Tail with Serpens Caput the Head. The constellation Ophiuchus is sandwiched in between them.

Snakes were useful for cures in the ancient times, the snake's venom could be used as both a cure and a poison depending on how it was used. The snake is supposed to be a snake that was brought back to life by another snake and the reborn snake was then killed by Asclepius, better known as Ophiuchus. Ophiuchus is nearly always drawn as holding or fighting the serpen but never explained why. Ian Ridpath

Other Meteor Showers

There are 13 Meteor Showers that occur during the year within this constellation based on information gathered from Adam Mickiewicz University (Poland). The list below are major ones and which I have a date period for.

NameActivityPeak ActivityClosest Star
eta Serpentids24th August  

List of Main Stars in Serpens

The following list contains the stars that make up the constellation. For a larger list of stars in the entire constellation area, please visit the For a list of named stars, that is stars that don't start HD or HIP, please visit Serpens Star List page.

NameBayerDistance (Lt.Yr.)Right AscensionDeclinationSpectral TypeColour
UnukalhaiAlpha Serpentis73.9615h 44m 16.00+06d 25` 31.9K2IIIOrange
Beta SerpentisBeta Serpentis155.0915h 46m 11.21+15d 25` 18.9A3VWhite
Gamma SerpentisGamma Serpentis36.7115h 56m 26.99+15d 39` 53.0F6VYellow/White
Delta SerpentisDelta Serpentis228.0915h 34m 48.19+10d 32` 19.9F0IVYellow/White
Nulla PambuEpsilon Serpentis70.4515h 50m 48.89+04d 28` 39.3A2mWhite
Eta SerpentisEta Serpentis60.4818h 21m 18.92-02d 53` 49.6K0III-IVOrange
AlyaTheta1 Serpentis154.6518h 56m 13.16+04d 12` 12.7A5VWhite
Iota SerpentisIota Serpentis190.0715h 41m 33.09+19d 40` 13.8A1VWhite
GudjaKappa Serpentis381.9215h 48m 44.41+18d 08` 30.4M1IIIRed
Mu SerpentisMu Serpentis169.6115h 49m 37.27-03d 25` 48.5A0VWhite
Xi SerpentisXi Serpentis105.2817h 37m 35.23-15d 23` 54.3F0IIIpYellow/White

Serpens Facts

Is a Zodiac Sign No
Brightest StarUnukalhai
Area636.928 sq. deg.
Percentage of Night Sky1.54%
Size Position23rd
Hemisphere Equatorial
Site Exoplanet Count17
Meteor Shower Count13
Nearest StarHIP 88574
Nearest Star with Exoplanet(s)HD 168443
Brightest StarUnukalhai
Dimmest StarTau6 Serpentis
Furthest StarHIP 90910
Bright Star Count65
Hipparcos Star Count1539
Main Star Count11
Messier Deep Space Object Count2
Bordering / Neighbouring / Surrounding ConstellationsCorona Borealis

*Note: The number of Non-Messier Deep Space Object Count relates to how many are covered on this site not how many there are.

List of Deep Space Objects (Galaxies, Nebulas, Supernovas, etc) in Serpens

NameTypeDistanceDeclinationRight Ascension
Eagle Nebula (M16, NGC6611)Star-Forming Nebula7000-13:4718h 18m 8
Hoag's ObjectRing Galaxy602,000,000 - 621,4021:35:0815h 17h 14m 4
IC 4756Open Star Cluster+05 29 2418 38 31m 2
Messier 5 (NGC 5904)Globular Cluster24500+02:0515h 18m 6
NGC 6027Galaxy in a Group of Galaxies+20 45 48.0715 59 12m 542

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