Galileo’s Discovery

Using his improved telescope in 1610, Galileo Galilei spotted four stars in a line near Jupiter.

Observations over the following weeks convinced Galileo that the stars were moving in orbit around the planet. The four Galilean moons were the first objects discovered to be orbiting another planet. His discovery was published in “Sidereus Nuncius,” the Starry Messenger.

HISTORY OF SCIENCE COLLECTIONS, UNIV. OF OKLAHOMA LIBRARIES