The Constellation Hydra

by Dominic Ford
Hydra Hydra
The constellation Hydra. Roll mouse over to see labels.
Source: Stellarium.

Hydra is the largest of all the constellations, visible in a equatorial and southern evening sky in the months around January and February.

Named after a water snake, Hydra is a long thin constellation, whose head lies slightly north of the celestial equator, but whose tail dips below a declination of 30°S. The angular distance between the head and tail of the snake is 85°.

Despite its large size, Hydra is a faint constellation with only one star brighter than third magnitude. The snake traces a path roughly parallel to the plane of the Milky Way and roughly 20° to its north. It is home to a few bright deep sky objects, including the open cluster M48, the galaxy M83 and the globular cluster M68.

In Greek mythology, Hydra is often identified as the Lernaean Hydra, a multi-headed creature slain by Hercules. According to various authors, the monster had six, nine, or even fifty heads, and perhaps even grew back a pair of heads for each one severed by Hercules. In the sky, however, it is depicted with only one head.

According to another myth, Hydra is the water snake in the tale of the crow and the cup, Corvus and Crater.

Date First Appeared
Sky Area
3.2% of the sky
1302.8 square degrees
Messier Objects
Hydra contains the following Messier objects: M48, M68, M83.
Caldwell Objects
Hydra contains the following Caldwell object: C59.
The following constellations neighbor Hydra: Antlia, Cancer, Canis Minor, Centaurus, Corvus, Crater, Leo, Libra, Lupus, Monoceros, Puppis, Pyxis, Sextans, Virgo.
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Brightest Objects in Hydra

Stars Open Clusters Globular Clusters Galaxies
Stars Open Clusters Globular Clusters Galaxies
Alphard (mag 2.0) IC 518 (mag 0.0) Messier 68 (mag 8.0) NGC 2574 (mag 0.0)
γ-Hya (mag 3.0) Messier 48 (mag 5.8) NGC 2617 (mag 0.0)
ζ-Hya (mag 3.1) NGC 2697 (mag 0.0)
ν-Hya (mag 3.1) NGC 2765 (mag 0.0)
π-Hya (mag 3.2) NGC 2847 (mag 0.0)
ε-Hya (mag 3.4) NGC 2864 (mag 0.0)
ξ-Hya (mag 3.5) NGC 2890 (mag 0.0)
λ-Hya (mag 3.6) NGC 2921 (mag 0.0)
μ-Hya (mag 3.8) NGC 2960 (mag 0.0)
θ-Hya (mag 3.9) NGC 2996 (mag 0.0)
C-Hya (mag 3.9) NGC 3058 (mag 0.0)
ι-Hya (mag 3.9) NGC 3140 (mag 0.0)
υ¹-Hya (mag 4.1) NGC 3208 (mag 0.0)
δ-Hya (mag 4.1) NGC 3296 (mag 0.0)
η-Hya (mag 4.3) NGC 3450 (mag 0.0)
D-Hya (mag 4.3) NGC 5182 (mag 0.0)
ρ-Hya (mag 4.3) NGC 5556 (mag 0.0)
β-Hya (mag 4.4) IC 513 (mag 0.0)
σ-Hya (mag 4.4) IC 534 (mag 0.0)
τ²-Hya (mag 4.6) IC 550 (mag 0.0)
υ²-Hya (mag 4.6) IC 879 (mag 0.0)
τ¹-Hya (mag 4.6) IC 2482 (mag 0.0)
F-Hya (mag 4.6) IC 2995 (mag 0.0)
2-Sex (mag 4.7) IC 3829 (mag 0.0)
O-Hya (mag 4.7) IC 4252 (mag 0.0)




Color scheme