Orion was the giant son of Poseidon. He was originally hired in the service of Oinopion of Chios. He was blinded and exiled from Chios for raping the king's daughter. He later asked Hephaestus to help restore his sight. He was advised to travel to the eastern palace of Helios to watch the sun rise, which would restore his eyesight. He did this and later returned to Chios to exact revenge. However, Oinopion hid in an underground chamber and could not be found.
He subsequently travelled to Crete were he met Artemis and joined her hunting party for a time. He earned the goddess' affection, which made him an enemy of Apollo. Apollo was jealous of his sister's companion and strove to kill him. He heard Orion boasting he could hunt all the animals of the Earth and, taking the opportunity, informed his great-grandmother, the Earth goddess Gaia. Gaia sent a giant scorpion to attack Orion. Orion fled into the sea where is abnormal height kept his head above water and away from the scorpion. He waded further out to sea to escape.
Artemis finds Orion's body
Apollo and Artemis were watching from a high hill and Apollo mocked his sister's accuracy. He challenged her to hit the dot that was floating out at sea and she shot it with ease, not realizing she killed her former companion. Artemis was distraught and placed his body, his hunting dogs and the scorpion in the sky as the constellations Orion, Canis Major, Canis Minor and Scorpius, destined to forever chase each other through the stars. This myth also explains why these two constellations are never in the sky at the same time.