Hydra - Sea Serpent

Learn about the constellation Hydra - Sea Serpent, location, facts, mythology, meteor showers and deep space objects.

Hydra is the largest modern constellation, at 1303 square degrees. Despite its size, Hydra contains only one reasonably bright star, Alphard.

Location: Northern Spring 10h RA -20° Dec

Hydra is the largest modern constellation, at 1303 square degrees. Despite its size, Hydra contains only one reasonably bright star, Alphard (α Hya, 30 Hya), which is of apparent magnitude 1.98. ρ Hydrae is a Mira variable star that ranges in magnitude between 3.5, when it is not easily visible to the naked eye, to 10.9 when a telescope is required to see it.

Hydra Mythology

The constellation Hydra resembles a twisting snake, and features as such in some Greek myths. In Greek mythology, a crow serves Apollo. It is sent to fetch water, but it rests lazily on the journey, and after finally obtaining the water in a cup, takes back a water snake as well, as an excuse. According to the myth, Apollo saw through the fraud, and angrily cast the crow, cup, and snake, into the sky.

Hydra Deep Space Objects

Hydra contains three Messier objects. M83, also known as the Southern Pinwheel Galaxy, is located on the border of Hydra and Centaurus, M68 is a globular cluster near M83, and M48 is an open star cluster at the western end of the serpent.

M48 (NGC 2548) is an open cluster that is visible to the naked eye under dark skies. Its shape has been described as "triangular"; this 80-star cluster is unusually large, more than half a degree in diameter, larger than the diameter of the full Moon.

In this table, the observation month represents the month in which the object reaches its highest point in the sky. It can also be viewed a few months before and after depending on your location. Direction is the compass direction in which the object is located, with Z meaning Zenith or overhead.

#		Common Name	Constellation	Month	Coords	Direction	Mag	Size (arcmin)	Type	Star Chart
C59 NGC 3242		Ghost of Jupiter Nebula	Hydra	Mar	10h 24.8m RA -18° 38m Dec	S	9.00	25	Planetary Nebula	🔍︎
C66 NGC 5694			Hydra	May	14h 39.6m RA -26° 32m Dec	S	10.20	3.6	Globular Cluster	🔍︎
M48 NGC 2548		Starfish Cluster	Hydra	Jan	08h 13.8m RA -05° 48m Dec	S	7.40	20	Open Cluster	🔍︎
M68 NGC 4590			Hydra	Apr	12h 39.5m RA -26° 45m Dec	S	9.67	11	Globular Cluster	🔍︎
M83 NGC 5236		Southern Pinwheel Galaxy	Hydra	May	13h 37.0m RA -29° 52m Dec	S	7.54	12.9x11.5	Galaxy	🔍︎