Ganymede, a satellite of the planet Jupiter. With a diameter of 3,270 miles (5,260 km), Ganymede is the largest satellite in the solar system, and is larger than the planet Mercury. Its surface is composed of ice and has distinct dark and light areas. The dark areas are heavily cratered and the light areas are covered by long, parallel channels. Ganymede was discovered by Galileo Galilei in 1610.
The sun warms our planet every day, provides the light by which we see and is necessary for life on Earth. But what is it exactly, and what will happen when it burns itself out?
The changing phases of the moon have given us an enduring curiosity about the dark side of the moon. But is there really a dark side of the moon? What would we see there?