Corvus and Crater: the punishment of Apollo's bird
The crow that lingered by a fig tree and lied to Apollo, the cup denied and the Hydra set on guard: the myth behind three constellations of spring.
On the long back of Hydra, the largest constellation in the sky, rest two small figures: a bird and a cup. Corvus, the Crow, is formed by an easily recognised quadrilateral of stars on spring evenings, while Crater, the Cup, fainter, has the shape of a chalice-like vessel. The closeness of these three constellations is no accident: the ancients read them as a single scene, a little moral fable written in the stars.
The cup, the fig and the lie
The myth, told by Ovid in the Fasti and reported by Hyginus and Eratosthenes, takes place during a sacrifice offered to Apollo. The god, needing pure water for the rite, sent his crow with a cup to fetch it from a spring. On the way the bird saw a fig tree laden with still-unripe fruit and decided to wait for it to ripen so as to eat it, forgetting its errand.
After some days had passed, the crow realised how late it was and looked for an excuse. It seized a water snake in its claws and returned to Apollo, claiming that the creature had prevented it from drawing from the spring. The god, who knew the truth, was not deceived. To punish it he set the crow, the cup and the serpent in the sky, so that Hydra would forever prevent the bird from drinking from Crater.
Why the crow is black
Another tale, told by Ovid in the Metamorphoses, explains the crow's colour. Once, it was said, its feathers were as white as a swan's. The crow told Apollo that his beloved Coronis was betraying him with a mortal; the god, blinded by rage, killed her with an arrow and only afterwards repented. He saved the son she was carrying, Asclepius, future god of medicine.
Regretting his deed, Apollo turned against the bearer of bad news and condemned it to have black feathers. In this story, as in that of the cup, the crow is a talkative and unreliable bird, punished for its words. Ancient tradition also attributed prophetic powers to crows and ravens, and their flight and cries were observed by the augurs.
The scene described by Aratus
Aratus, in the Phaenomena, already describes the scene as we see it: on the coils of Hydra rests the cup, and towards the tail stands the image of a crow that seems to peck at the serpent. The arrangement of the stars thus comes before the tale and supports it, while the tale offers a narrative explanation. Crater, for its part, was sometimes also identified with the cup of Dionysus, the vessel in which the Greeks mixed wine and water.
In the Middle Ages these figures were taken up by the Arabic astronomical tradition and then by the European one, which kept the Latin names Corvus and Crater. Corvus, though small, is useful for finding one's way: two of its stars point towards Spica, the chief star of Virgo. In Ptolemy's catalogue, in the second century AD, Corvus and Crater already appear among the forty-eight classical constellations, beside Hydra.
Corvus and Crater thus tell a small lesson about responsibility and the spoken word. The messenger who puts his own desire before his duty, and then covers the failure with a lie, is punished with eternal thirst. Every spring, when the three constellations rise together above the horizon, the sky repeats the scene: the bird very close to the cup, yet forever unable to reach it.