A. Galileo Galilei
B. Nicolaus Copernicus
C. Johannes Kepler
D. William Herschel
Explanation: Galileo observed Io, Europa, Ganymede and Callisto in 1610. They are collectively known as the Galilean moons.
A. Galileo Galilei
B. Nicolaus Copernicus
C. Johannes Kepler
D. William Herschel
Explanation: Galileo observed Io, Europa, Ganymede and Callisto in 1610. They are collectively known as the Galilean moons.