Location.—The head of Hydra, a striking and beautiful arrangement of stars, lies just below the Bee Hive, in Cancer, 6° south of Acubens in that constellation, and forms a rhomboidal figure of five stars.
Hydra is about 100° in length and reaches almost from Canis Minor to Libra. Its stars are all faint except Alphard, or the Hydra's heart, a second-magnitude star remarkable for its lonely situation, southwest of Regulus, in Leo. A line drawn from γ Leonis through Regulus points it out. It is of a rich orange tint. Castor and Pollux, in Gemini, point southeast to it.
The constellations Crater, the Cup, and Corvus, the Crow, both stand on the coils of Hydra, south of Denebola, the bright star in the tail of the Lion.
Hydra is supposed to be the snake shown on a uranographic stone from the Euphrates, 1200 b.c.
The little asterism Sextans, the Sextant, lies in the region between Regulus and Alphard. It contains no stars brighter than the fourth magnitude.