Eridanus is a river in northern Italy, now known as the River Po. Called by Virgil the "king of rivers," Eridanus was made famous in connection with the death of Phaethon.

Phaethon was the son of Phoebus Apollo and the nymph Clymene. For his birthday one year, Phaethon asked his father for some proof that he was indeed the son of the sun-god. Apollo said he would give the boy any gift he desired as a token of his fatherly love, and Phaethon promptly asked for the chance to drive the chariot of the sun. His father balked, knowing that no mortal youth could possibly have the strength necessary to control the horses. However, Phaethon insisted, and Apollo had granted his word.

Phaethon drove off on the route of the sun, but sure enough, he could not control the powerful horses. He drove too close to the heavens, and then plunged too close to the earth, scorching both realms. Gaia endured the sun's heat until she could bear it no more, and then she called upon Jupiter for help:

The omnipotent father called upon the gods and even upon the sun himself, who had bestowed his car upon Phaethon, to be his witnesses that, if he did not bring help, the whole world would come to a grievous end. Then he mounted up to the highest point of heaven, that height from which he is wont to spread clouds over the broad lands of earth, whence he sends forth his thunderings and hurls his flashing bolts: he had no clouds then to draw over the world, no rain to shower down from the skies. He sent forth a thunderclap and, poising his bolt close by his right ear, launched it against the charioteer....Phaethon, with flames searing his glowing locks, was flung headlong, and went hurtling down through the air, leaving a long trail behind: just as a star, though it does not really fall, could yet be thought to fall from a clear sky. Far from his native land, in a distant part of the world, the river Eridanus received him, and bathed his charred features" (Metamorphoses II 304-327).

As a constellation, Eridanus is the longest in the sky, meandering from Orion to Cetus.