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Moons of Jupiter

[top left] Callisto: third largest moon in our solar system

[top right] Io: the dark spot on the center left is the volcano Prometheus

[bottom left] Ganymede: largest moon in our solar system & the only moon we know of to have a magnetic field

[bottom right] Europa: NASA has detected phyllosilicates (clay-ish minerals) on this moon’s ice ladden crust

I thought I’d start off a series of photos about the moons in our Solar System. This is a wonderful image of Callisto, a moon in the Jovian system and one of the 4 Galilean moons. It is the 3rd largest moon in the Solar system, with a diameter of 4821km. For comparison, the diameter of Mercury is 4878km. Its orbit around Jupiter is tidally locked, so its keeping the same face turned to Jupiter. Its appearance is very unique in our Solar System; There’s nothing quite like it, with the surface being extremely heavily cratered and very old. (。◕‿◕。)

Luca Cambiaso- Diana Discovering The Pregnancy Of Callisto. 


Callisto by Melissa Lee.

Callisto was a nymph (or, according to some sources, the daughter of Lycaon) who was associated with the goddess of the hunt, Artemis. 

. Young women who were devoted to the goddess hunted with her regularly and remained virgins, like Artemis herself. Callisto had upheld these ideals faithfully, and she quickly became Artemis’ favorite.

While Callisto spent her days and nights with Artemis’ other followers, she caught the eye of Zeus. Knowing that the maiden had taken a vow of chastity, Zeus resorted to deception to get at Callisto. He came to her disguised as Artemis, and the young huntress let down her guard. Seizing the opportunity Zeus raped her.

Callisto became pregnant and tried desperately to conceal her condition form the goddess. After all, she had, in a way, broken her vow to the goddess and she feared her anger. Callisto had been successful for a time, but then a day came when all of the young women who followed Artemis disrobed to bathe together in the spring. By now Callisto was beginning to show, and once she was naked her secret was revealed. Artemis was furious and she banished the young woman from her fold. Callisto wandered off to have her child alone.

Hera decided that this was the time to exact her revenge. She gripped Callisto’s hair and threw her to the ground where the new mother was transformed into a bear. The hunter became the hunted. The child that Callisto had by Zeus was spirited away by Hermes to be raised by his mother, Maia. He was named Arcas, meaning “bear,” and he grew up to be a fine hunter himself. Some sources have the bear captured and taken to Callisto’s own father, Lycaon. 

According to some sources, Artemis herself killed the bear that was once Callisto, but it is usually accepted that when Arcas was out hunting as a young man he encountered the bear. Callisto recognized the handsome youth as the son she could not raise herself. Forgetting her present form, she tried to come near him, but her loving mother’s arms were now strong, furry paws, and her once soothing voice was now a rumbling growl. The bear scared Arcas, and he took aim at her with his spear. Zeus took pity on his former victim and intervened. He placed Callisto in the sky as the constellation Ursa Major, or “great bear,” and then took Arcas and placed him in the sky near his mother as Ursa Minor, the “little bear.”

Hera was not pleased with this arrangement, especially since Callisto was another of her husband’s infidelities. She went to her nurse,  Tethys, the wife of Oceanus and beseeched her to punish Callisto and Arcas. Tethys decided to deprive the pair of water, and so the great bear and the little bear are cursed to circle in the skies, never to dip below the horizon for a refreshing bath or a cool drink. Here the peoples of ancient Greece explained why the two constellations are circumpolar, visible all year round.