Erich Lessing / Art Resource, NY As shown in his sketches, Galileo saw that the moon was no perfect sphere. Biblioteca Nazionale, Florence / Granger Collection, New York Galileo's work pleased the ...

Galileo was the first person to observe the rings of Saturn. He spent hour after hour on painstaking drawings of the Moon through its phases, observed Venus and Mars, and even made sketches of ...

Initially believing they were distant stars, Galileo’s repeated observations over several nights and realized they were moons orbiting the gas giant. And thus, Io, Europa and Ganymede became ...