Happy Birthday, Galileo Galilei, born February 15, 1564.
On the nights of January 7/8, 1610, Galileo Galilei noted in his notebooks the discovery of the first 4 Jovian moons, which he named after the powerful Medici family, naming them Medicean I, II and III. The name Europa (second from right) comes from Greek mythology-Europa was abducted by Zeus (the Greek name for Jupiter) in the form of a bull and bore him many children. Io (the yellow moon on the left) is also named for a child of Zeus (Jupiter) the daughter of Inachus, who was raped by Jupiter. Jupiter, in an effort to hide his crime from his wife, Juno, transformed Io into a heifer. Calllisto (on the far right) was named for another seduction of Jupiter. Callisto was the daughter of Lycaon, who was a follower of Artemis, famous as goddess of the hunt and for her chastity. To punish Callisto for lying with Jupiter, Artemis banished her. Without protection, Jupiter was forced to change Callisto and her son into bears to hide them from his wife Hera’s fury. Eventually, Jupiter placed them both in the sky as the Ursa Major and Minor, the Big and Little Bears (known today as the Big and Little Dippers). Ganymede (largest moon pictured here, third from right) was the fourth moon discovered by Galileo, named for the shepherd boy known for his incredible beauty and kidnapped by Jupiter. These names would not become common for several hundred years. Today, Jupiter has fifty named moons:
1. Io 2. Europa
and an additional 16 provisional moons:
All images courtesy NASA. Thanks also to NASA for additional historical background