Galileo Journal Translation
Date: 7 Jan 1610

A translation of the key passages of Galileo Galilei's journal detailing his discovery of four moons orbiting Jupiter.


Galileo Galilei made these sketches after discovering four moons orbiting Jupiter in January 1610. The moons, later named Io, Europa, Callisto and Ganymede, were the first discovered beyond Earth.


Their discovery also led to the demise of the popular theory that Earth was the center of the universe and an understanding that the planets in our solar system orbit the Sun.

Credit: NASA