Zeus gave Arcas to the goddess Maia to raise him.
Take care of Arcas and teach him all there is to know about being human. But please never mention his mother or how he came to you.
When Arcas became human he became the king of the land, which was named after him, Arcadia.
I am king and this land shall be called Arcadia!
One day, while Arcas was hunting in the forest, he met a bear. This bear was his mother Callisto. Arcas, who didn't know the truth about his mother, was getting ready to throw his javelin and kill the bear.
Zeus, from Mt. Olympus, saw the tragedy coming and before the javelin hit Callisto, he turned them both into constellations.
NO! NOT CALLISTO!
Zeus turned them into Ursa Major and Ursa Minor, meaning big and small bear in Latin. Here they perpetually circle the northern star, to never set over the horizon again.