Astronomers know there are more than sixty moons within the Solar System and think there may be many more. Most from the known moons orbit the four giant planets: Jupiter, Saturn, Uranus and Neptune. It is no coincidence that these are also the four ringed planets, simply because the lives from the rings and moons are linked.

All the substance in both moons and rings dates from the birth from the Solar Program 4600 million years ago. Their formation started when substance left more than after the creation from the Sun formed into a disc close to it. The fragments in the disc ultimately came together (coalesced) to form the planets.

In the same way, fragments of substance left over from the creation of some planets formed discs revolving close to them. This material also coalesced, and in time formed spheres orbiting the planets – moons. Fragments very close to the planets – within the Roche limit – had been not able to form moons, because planetary gravity constantly pulled them apart. Instead they remained in pieces and produced planetary rings.

The moons of Jupiter, Saturn, Uranus and Neptune had been all created in this way, but moons from the other planets have really various origins. Astronomers now believe Earth’s moon was produced when a large space rock collided with the young Earth. Fragments from the rock and material ejected from Earth during the collision then started to orbit our planet, ultimately coming together to produce the Moon. Mars’ two moons, Phobos and Deimos, are probably asteroids trapped in orbit by Mars’ gravity. The origin of Pluto’s moon, Charon, is unknown. Actually, the origin from the planet itself is uncertain. It’s possible that both bodies are asteroids that have been caught in a planetary orbit around the Sun.