Hydrus (Pronounciation:Hide-rus, Abbrev:Hyi, Latin:Hydri) is a constellation, one of 88 constellations that the night sky is divided into. The sky is not divided up equally between the constellations. Hydrus takes up 243.035 sq. degrees of the night sky which equates to 0.59% of the night sky. Hydrus is the 61st largest in terms of size in the night sky.
The constellation name means The Water Snake . It was not one of the original constellations that had been devised by Ptolemy, instead it was created by Pieter Dirkszoon Keyser and Frederick de Houtman years later.
There are 6 stars that make up the main constellation. The hipparcos satellite scanned and detailed 659 stars. There are 20 stars that can be seen with the naked eye in the constellation on a very clear night sky.
Hydrus is not a member of the Zodiac group of twelve constellations that appear when the Sun sets. Hydrus is a southern hemispheric constellation which means it can't be seen easily or at all from the northern hemisphere.
There are no 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.
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 24.33 light years and the furthest main star is a distance of 339.40 light years. The average distance to the main stars is 156.85 light years.
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.
The nearest star to Earth is Beta Hydri which is roughly about 24.33 Light Years from the Earth. The nearest star to the Earth with an exoplanet is GJ 3021 which is about 57.07 Light Years.
The furthest star that is located in the constellation is HIP 120027 and it is 108721.1 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.
The brightest star in Hydrus is Beta Hydri and is located about 437.29 light years from the Sun. The star has a apparent magnitude of 2.82 but an absolute magnitude of 3.46 when the star is viewed from a distance of 10 Parsecs or 32.6 Light Years. The star is only recognised as being Beta Hydri rather than having Alpha status.
The dimmest star that can be seen in Hydrus with the naked eye is Kappa Hydri. The dim star has an apparent magnitude of 5.99. 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.
There is no Greek Legend behind this constellation. It was created by Pieter Dirkszoon Keyser and Frederick de Houtman to fill in the voids in the astronomical charts in the southern hemisphere. The Hydrus is a small male water serpent.
There are 3 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.
|Name||Activity||Peak Activity||Closest Star|
|Alpha Hydrids||15-30 Jan||20/21 Jan||Head of Hydrus|
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 Hydrus Star List page.
|Name||Bayer||Distance (Lt.Yr.)||Right Ascension||Declination||Spectral Type||Colour|
|Head of Hydrus||Alpha Hydri||71.79||01h 58m 45.87||-61d 34` 11.7||F0V||Yellow/White|
|Beta Hydri||Beta Hydri||24.33||00h 25m 39.20||-77d 15` 18.1||G2IV||Yellow|
|Gamma Hydri||Gamma Hydri||214.02||03h 47m 14.23||-74d 14` 21.3||M2III||Red|
|Delta Hydri||Delta Hydri||139.68||02h 21m 45.02||-68d 39` 33.9||A3V||White|
|Epsilon Hydri||Epsilon Hydri||151.85||02h 39m 35.22||-68d 16` 01.0||B9III||Blue/White|
|Nu Hydri||Nu Hydri||339.40||02h 50m 28.54||-75d 04` 00.8||K3III||Orange|
|Is a Zodiac Sign||No|
|Brightest Star||Beta Hydri|
|Area||243.035 sq. deg.|
|Percentage of Night Sky||0.59%|
|Site Exoplanet Count||11|
|Meteor Shower Count||3|
|Nearest Star||Beta Hydri|
|Nearest Star with Exoplanet(s)||GJ 3021|
|Brightest Star||Beta Hydri|
|Dimmest Star||Kappa Hydri|
|Furthest Star||HIP 120027|
|Bright Star Count||20|
|Hipparcos Star Count||659|
|Main Star Count||6|
|Messier Deep Space Object Count||0|
|Bordering / Neighbouring / Surrounding Constellations||Eridanus|
*Note: The number of Non-Messier Deep Space Object Count relates to how many are covered on this site not how many there are.
|NGC 1466||Globular Cluster||150,000||-71 40 18||03 44 33m 0|
|NGC 602||Open Star Cluster||-73 33 38.13||01 29 32m 133|
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