|Callisto and Zeus in disguise of Artemis|
Callisto or Kallisto was the daughter of Lycaon, king of Arcadia. She was one of Artemis hunting attendants. As a companion of Artemis, Callisto took a vow to remain a virgin. Zeus, who was in love with Callisto, appeared to her in disguise of Artemis, gained her confidence and took advantage of her.
Zeus turn Callisto into a bear when Hera came across them as they were consorting or zeus jealous wife Hera angrily transformed her into a bear. Hera also persuaded Artemis to think she was a normal bear and to shoot her. Zeus sent Hermes to recover the child, Arcas from her womb and deliver him into the care of Maia. Zeus came to rescue turning Callisto into the constellation Arctos, the great bear also known as Ursa Major. Later she was joined by her son who became the nearby constellation Arctophylase, the little bear, also known as Ursa Minor.
|Callisto pregnant condition was discovered while bathing|
According to other version Callisto pregnant condition was discovered some months later while bathing with Artemis and her fellow nymphs. Artemis in her anger transformed Callisto into a bear. Hunters then caught and delivered her son Arcas. Later when her son was grown, Callisto, still a bear, encountered the son hunting in the forest. When Arcas was about to kill his own mother with his javelen, Zeus prevent the tragedy by placing mother and son amongst the stars as Ursa Major and Ursa Minor respectively. Hera holds grudge against Callisto asked Tethys and Oceanus not to allow Callisto to enter thier realm, the ocean. Due to this Callisto must circle the North Star and never set over the horizon (circumpolar position).