Galileo Galilei

As twilight ends this winter, look to the east. You may see a very bright “star” that does not twinkle. This is Jupiter, the largest planet of the Solar System, eleven times the diameter of the Earth.

For this episode of Western Slope Skies, a look at the moons of Jupiter, and the two Galileos - the man and the machine.

In 1610, Galileo Galilei became the first person to observe another planet, Jupiter, and its 4 largest moons, Callisto, Europa, Ganymede, and Io.   For the next 380 years, most scientists believed that those moons were similar to our Moon, that is, rocky spheres without activity or atmosphere.