Jupiter outshines everything else high in the sky these evenings, noticed only glancingly by most (if noticed at all). Four hundred and two years ago this month, it was a different story.

In the city of Padua in Italy during the Renaissance, the brash and controversial scholar Galileo Galilei was just begin­ning to publicize a record-­breaking new claim. Using the magic tubes with which he was already building a reputation — but which were notoriously hard for anyone else to aim and use — he declared to have seen, at Jupiter, proof that the Earth is not creation’s only center of motion.