The Outer Solar System encompasses the gas and ice giants—Jupiter, Saturn, Uranus, and Neptune, along with their moons, rings, and the Kuiper Belt. It is characterized by volatile-rich compositions and lower temperatures.
It spans from beyond the Asteroid Belt at about 5 AU to 50 AU from the Sun.
Sometimes referred to as the "Giant Planet Region," the term distinguishes it from the rocky inner planets. It reflects its position and the dominance of massive, gaseous worlds formed beyond the frost line.
Key events include the Voyager missions' grand tour (1977–1989), discovering rings and moons. The Cassini-Huygens probe's exploration of Saturn (2004–2017) revealed Enceladus' geysers and Titan's lakes.
