Planet Earth
International Astronomical Union WGSN

IAU: Hydra

Profile / Characteristics

English translationLatin declination and pronunciationsSize/ °²# stars
the Female Water SnakeHydra – HIGH-druh
Hydrae – HIGH-dree

Ancient Globes

Farnese Globe

Kugel Globe

Mainz Globe

Ancient Lore & Meaning


English translation by Douglas Kidd (1997).
Aratus: Phaenomena, Cambridge Classical Texts and Commentaries, Series Number 34

Online available: translation by Mair (1921) 


[443] Another constellation trails beyond, which men call the Hydra. Like a living creature it winds afar its coiling form. Its head comes beneath the middle of the Crab, its coil beneath the body of the Lion, and its tail hangs above the Centaur himself. Midway on its coiling form is set the Crater, and at the tip the figure of a Raven [Corvus] that seems to peck at the coil. [449] There, too, by the Hydra beneath the Twins brightly shines Procyon. [51x] and the coil of the gleaming Hydra: in it, too, the dim-lit Crater and the Crow and the scanty-starred Claws and the knees of Ophiuchus are borne. [595] Up rises the Hydra’s head and the bright-eyed Hare and Procyon and the forefeet of the flaming dog. [600] The Hydra rises higher as far as Crater, and before her the Dog brings up his hind feet, dragging behind him the stern of Argo of many stars. [607] Nor can the rising Claws [Libra], though faintly shining, pass unremarked, when at a bound the mighty sign of Boötes rises, jeweled with Arcturus. Aloft is risen all of Argo, but the Hydra, shed as she is afar over the heavens, will lack her tail. [663] So she is borne towards the West, but other signs in the East the vault of heaven brings from below, the remaining half of the Crown and the tail of the Hydra, and uplifts the body and head of the Centaur and the Beast that the Centaur holds in his right hand. But the fore-feet of the Centaur-Knight await the rising of the Bow. => pi Hya gehört für Aratus dazu But she sinks beneath the verge the coiling neck and all the brow of the gleaming Hydra. [700] Yet many a coil of the Hydra remains, but Night engulfs her wholly with the Centaur, when the Fishes [Pisces] rise; with the Fishes the Fish which is placed beneath azure Aegoceros rises

French translation by:
Jordi Pàmias i Massana and Arnaud Zucker (2013). Ératosthènes de Cyrène – Catastérismes, Les Belles Lettres, Paris

English version in:
Robin Hard (2015): Eratosthenes and Hyginus Constellation Myths with Aratus’s Phaenomena, Oxford World’s Classics

Early Modern Interpretation


As one of their first tasks in the 1920s, the newly founded International Astronomical Union (IAU) established constellation standards. The Belgian astronomer Eugène Delporte was assigned to the task to define borders of constellations parallel to lines of declination and right ascension. They were accepted by the General Assembly in 1928. The standardized names and abbreviations had already been accepted in 1922 and 1925.  

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