Constellation of Hydra
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Image and text ©2008 Akira Fujii/David Malin Images.

In the picture above north is at the top and the image covers 90.3 x 112.9 degrees.
Image centre is located at 10:59:34.9, -05:42:01 (H:M:S, D:M:S, J2000) Astrometric data from

Hydra along the southern horizon
Best seen in the early evening during March to May

In Greek mythology, Hydra the Water Snake, guards the entrance to the Underworld (or the Golden Fleece). In another legend it guards the cup of water (Crater, the goblet of Apollo) from adjoining Corvus, the Crow, forever denying him a drink of water. Hydra was a fresh-water serpent born to Echidne and Typhon and was the beast which Hercules had to slay as the second of his twelve labours. This is perhaps a retelling of an earlier Babylonian story in which the hero Gilgamesh kills a many-headed monster.

Hydra is the largest of the 88 modern constellations at over 1,300 square degrees, extending over 100° of sky. Despite its enormous size, it is hard to identify because the stars are so faint. In ancient times, Hydra was even bigger -- the smaller constellations of Corvus and Crater, together with Sextans, the sextant, were created to reduce Hydra to a more manageable size. Above is the whole of Hydra, but the scale is necessarily small. On more detailed images are the west and central parts of this sprawling constellation. The compact group of stars in the head of Hydra are best seen in the photograph that includes Sextans.

The orange line on the above image is the plane of the ecliptic, along which the Sun and planets appear to move through the zodiacal constellations. The brightest 'star' image here is the planet Jupiter, and at the extreme western (right) edge is the much fainter image of Saturn, firmly on the ecliptic.

Named stars in Hydra (Greek alphabet)   Alphard (α Hya), Al Minliar al Shuja (σ Hya), Ashlesha (ε Hya), Cauda Hydrea (γ Hya), Hydrobius (ζ Hya), Pleura (ν Hya).

Constellations adjoining Hydra
Antlia, Cancer, Canis Minor, Centaurus, Corvus, Crater, Leo, Libra, Lupus (corner), Monoceros, Puppis, Pyxis, Sextans, Virgo.

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David Malin, 2009 October 15