The wood-nymph Callisto was a maiden in Arcadia. She was a huntress, and was one of Diana’s warriors.
Jupiter caught sight of her and immediately desired her. He took on the shape of the goddess Diana and spoke to Callisto, who was delighted to see her mistress. She began to tell him of her hunting exploits, and he responded by raping her. She resisted him as much as she could, but with little success.
Callisto unfortunately bore a son to Jupiter, Arcas, who infuriated Juno. Out of jealousy, she transformed Callisto into a bear. She lived for a while in the wild, until Arcas came across her while hunting. Unknowingly, he was about to kill his mother, but Jupiter took mercy on Callisto and stopped Arcas’ hand. He transformed him into a lesser bear and placed them both into the heavens as neighbouring constellations.
URSA MAJOR, representing Callisto, is one of the most familiar constellations. It includes the big dipper, perhaps the most-recognized constellation in the heavens.