Hydrus constellation: how to find it, when to see it and what is in it
In short
Hydrus (Hyi) is a southern constellation covering 243 square degrees, number 61 of 88 by size. Its brightest star is β Hyi, a yellow subgiant, magnitude 2.8. It is best seen in the evening in December. It never rises over London — it is visible south of 9° north. Its neighbours in the sky: Dorado, Eridanus, Horologium, Mensa, Octans, Reticulum, Tucana.
Area: 243 square degrees, 61 of 88 · Neighbours: Dorado, Eridanus, Horologium, Mensa, Octans, Reticulum, Tucana · Updated 10 October 2026
How to find Hydrus
- 1
Where it is visible
The constellation rises above the horizon south of 9° north and is well seen from the southern hemisphere.
- 2
Use the neighbours
Find it from the neighbouring constellations: Dorado, Eridanus, Horologium, Mensa.
- 3
Brightest stars
The brightest stars of the figure: β Hyi (2.8ᵐ), α Hyi (2.9ᵐ), γ Hyi (3.2ᵐ).
When it is visible over London
| Month | Where and when | Conditions |
|---|---|---|
| January — december | — | never rises |
Stars of the constellation
| Star | What it is | Magnitude |
|---|---|---|
| β Hyi | yellow subgiant | 2.8ᵐ |
| α Hyi | yellow-white main-sequence star | 2.9ᵐ |
| γ Hyi | red giant | 3.2ᵐ |
| δ Hyi | white main-sequence star | 4.1ᵐ |
| ε Hyi | blue-white main-sequence star | 4.1ᵐ |
Hydrus FAQ
When is the best time to see Hydrus?
Where is Hydrus in the sky?
What is the brightest star in Hydrus?
Neighbouring and other constellations
Related
Constellation lines: Stellarium, CC BY-SA · star names: IAU WGSN, CC BY 4.0