This is the third-smallest constellation in the sky, with no stars brighter than fourth magnitude, but it was well-known to the Greeks. Aratus described it as ‘alone, without a bow’ since there is no sign of the archer who might have shot it.
There are at least three different stories to account for the arrow in the sky. Eratosthenes said it was the projectile with which Apollo killed the Cyclopes because they made the thunderbolts of Zeus that struck down Apollo’s son, Asclepius. According to this story, Asclepius was a great healer with the power to raise the dead, but Zeus killed Asclepius when Hades, god of the Underworld, complained that he was losing business. Asclepius is commemorated in the constellation Ophiuchus.
Hyginus said that Sagitta was one of the arrows with which Heracles killed the eagle that ate the liver of Prometheus. It was Prometheus who moulded men out of clay in the likeness of the gods, and gave them fire that he had stolen from Zeus. Prometheus carried the fire triumphantly in a vegetable stalk like a runner bearing the Olympic torch. Zeus cruelly punished him for this theft by chaining him to Mount Caucasus, where a long-winged eagle ate his liver during the day. But at night the liver grew again for the eagle to resume his feast in the morning. Heracles freed Prometheus from this eternal torture by shooting the eagle with an arrow.
Germanicus Caesar identified Sagitta as the arrow of Eros which kindled in Zeus his passion for the shepherd boy Ganymede, who is commemorated by the constellation Aquarius. Now, according to Germanicus, the arrow is guarded in the sky by the eagle of Zeus – and Sagitta does indeed lie next to the constellation of the eagle, Aquila. None of the stars of Sagitta are named.