Callisto
2 of the 6 encyclopedias on this shelf carry an entry for Callisto. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
in Greek mythology, an Arcadian nymph. Zeus admired Callisto and the jealous Hera changed her into a bear. Callisto was very unhappy in this new form. She was afraid of the other wild beasts, even of other bears, and she was lonely. At last she saw her own son, Arcas, approaching. She sprang forward to embrace him; but Arcas, not recognizing his mother, was about to slay her with his spear, when zeus in pity snatched them up, and changing Arcas too into a bear, set them both in the sky, where they formed the constellations of the Great and Little Bear. Hera was incensed that such an honor should come to Callisto as a result of her punishment. She went to Tethys and Oceanus, who ruled the ocean, and begged them to help her. They could do little, but they forbade the Great Bear and the Little Bear to come into their waters. So these two constellations move round and round in the heavens; but never sink, as do other stars, below the ocean. There is considerable diversity in the stories of Callisto told by different writers. The foregoing account is Ovid’s version of the tale. According to others, Callisto was an attendant of Artemis and was changed by her into a bear, and her son given to Maia to bring up . Another story is that Artemis herself killed the bear Callisto, and that she was transplanted to the skies as the constellation of the Great Bear, while Arcas was changed to Arcturus in the constellation called Bootes, or the Watcher of the Bear. This is consistent with the story of Cynosura, who was transformed into the Little Bear. Milton in II Penseroso alludes to the fact that the constellations of the Bear never disappear below the horizon: Let my lamp, at midnight hour Be seen in some high, lonely tower, Where I may oft outwatch the bear See Cynosura
Collier's New Encyclopedia (1921)
in classical mythology, an Arcadian nymph. Zeus's love for her aroused the jealousy of Hera, who induced Artemis to put Callisto to death. Subsequently Zeus transformed Callisto into the constellation Arctos or the Bear.
What Has Changed in the Last Century
As myth, both accounts still stand: the Arcadian nymph loved by Zeus, turned into a bear, and set in the sky as the Great Bear, with Ovid's version and the rival tellings laid out much as a classicist would summarise them today. What has moved is the name's centre of gravity. When Aiton's wrote in 1910 and Collier's in 1921, the fourth Galilean satellite of Jupiter, discovered in 1610, was still commonly called Jupiter IV; the name Callisto, suggested in the seventeenth century, only became the standard usage in the twentieth and was formally sanctioned by the International Astronomical Union. Spacecraft have since visited it he the Galileo orbiter, which studied the Jovian system from 1995 to 2003, found evidence hinting at a salty layer beneath Callisto's heavily cratered ice, and the European JUICE mission launched in 2023 is designed to fly past it.
Written for this edition, 2026.