Constellation, Male Water Snake
Hydrus
The lesser water snake, a southern figure from the first Dutch voyages to the East Indies. It winds between the two Magellanic Clouds, near the south celestial pole.
From New York the constellation Hydrus never rises above the horizon: it belongs to the other hemisphere’s sky.
From New York the constellation Hydrus never rises above the horizon: it belongs to the other hemisphere’s sky.
In the 3D sky
The sky over New York turned towards Hydrus. Drag to look around.
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Evening visibility over the year
Height of the constellation’s centre above the horizon at 10 pm local time on the 15th of each month, from New York. Above about 30° it is well placed.
Name and history
Hydrus has no ancient myth. It is one of twelve figures based on the observations of the Dutch navigators Pieter Dirkszoon Keyser and Frederick de Houtman, which Petrus Plancius first showed on a globe in 1598. De Houtman listed it in 1603 as De Waterslang, the water snake. It stands for the sea snakes the sailors would have seen on their voyage rather than a monster of legend. Johann Bayer’s Uranometria of the same year was the first printed atlas to show it.
It is a male water snake, to tell it apart from the far older and female Hydra. Nicolas-Louis de Lacaille called it l’Hydre Mâle in 1756. Few figures have been redrawn so often. Lacaille rerouted it between the two Magellanic Clouds, gave some of its stars to Tucana, Horologium and Reticulum, and cut off its tail to make room for his new constellation Octans, which holds the south celestial pole.
Sources: Ian Ridpath, Star Tales: Hydrus, Ian Ridpath, Star Tales: Chapter One, page 3 (de Houtman’s catalogue)
Brightest stars
| Star | Designation | Magnitude | Distance |
|---|---|---|---|
| β Hyi | β Hyi | 2.82 | 24 light-years |
| α Hyi | α Hyi | 2.86 | 72 light-years |
| γ Hyi | γ Hyi | 3.26 | 214 light-years |
| δ Hyi | δ Hyi | 4.08 | 140 light-years |
| ε Hyi | ε Hyi | 4.12 | 152 light-years |
| η2 Hyi | η2 Hyi | 4.68 | 219 light-years |
| ν Hyi | ν Hyi | 4.76 | 339 light-years |
| ζ Hyi | ζ Hyi | 4.83 | 284 light-years |
Facts
| Area | about 244 square degrees (60 of 88) |
|---|---|
| IAU abbreviation | Hyi |
| Sky | Southern sky |
| Origin | First shown on the 1598 celestial globe of Petrus Plancius and Jodocus Hondius, from observations by Pieter Dirkszoon Keyser and Frederick de Houtman |
| Stars brighter than magnitude 5 | 8 |
| Centre (J2000) | 2.4 h, -70° |
Deep-sky objects
Galaxies, clusters and nebulae brighter than magnitude 9, from the OpenNGC catalogue. Most need binoculars or a telescope and a dark sky.
No deep-sky object brighter than magnitude 9.
Boundaries: International Astronomical Union, via Astronomy Engine. Areas are computed from the boundaries by sampling (within about one percent). Names and lines: Stellarium. Stars: HYG Database. Deep-sky objects: OpenNGC. Calculated with Astronomy Engine, an open-source library verified against the US Naval Observatory and NASA JPL. Data sources
How to use this page
Choose your place and a night at the top. The answer and the 3D view show where the constellation is, when it is highest and whether it rises at all from where you are. The chart shows its stars and lines, and the tables list its brightest stars and the deep-sky objects inside it.
Frequently asked questions
When is a constellation best seen?
When it is highest in a dark sky, which the page gives for the night you pick. Each constellation is best placed in a particular season, because the stars rise about four minutes earlier every night.
Why can I not see a constellation from my place?
Constellations far south of the celestial equator never rise from northern places, and those far north never rise from southern ones. The page says when this is the case.
What are the constellation boundaries?
The International Astronomical Union divides the sky into 88 areas with official boundaries. The stick figures are only a drawing aid, the boundaries say which constellation a point in the sky belongs to.
Related guides
- How to learn the constellationsStart with one bright pattern you cannot miss, use it as a signpost to its neighbours, and come back a month later: the sky will have turned, and you will know a little more of it.
- Altitude and azimuth: finding things in the skyTwo angles tell you exactly where to look: which direction, and how high.
- Light pollution and dark skies: the Bortle scaleFrom a city centre you can count a few dozen stars. From a truly dark site you can count a few thousand, with the Milky Way bright enough to cast a shadow. The Bortle scale puts a number on the difference.
- Binoculars for stargazing: what to buy and what to look atA pair of 7x50 or 10x50 binoculars shows the craters of the Moon, the moons of Jupiter, dozens of star clusters and the Andromeda Galaxy, for a fraction of the cost of a telescope.