Callisto’s story is one of many wherein a youth wrongfully feels the wrath of the divine through no fault of their own.
Callisto’s father had been a king of Arcadia, and she herself a maiden follower of Artemis. Callisto’s beauty alone would be her downfall, as Zeus saw her and fell in love. Hera in her jealous rage transformed Callisto into a bear; however, a son by Zeus was already birthed by the name of Arcas. When Arcas was grown and hunting, Hera intended for his happening along his mother as a bear so he would mistakenly kill her.
Zeus prevented this by snatching Callisto from harm’s way and placing her among the stars where she is called the Great Bear. Her son twinkles alongside her in the sky as the Lesser Bear.
Hera was undoubtedly furious at this honor given to her rivals and beseeched Poseidon to never allow the stars of Ursa Major and Ursa Minor to touch his waters. Thus providing a poetic explanation for why the constellations never set below the horizon in their circumpolar path.