Saturn

What's there

Saturn's rings are the planet's signature feature, but they are also extraordinarily thin: 280,000 km across and typically only 10 to 100 meters thick. The rings are made almost entirely of water ice, in chunks ranging from dust grains to boulders. They are young — current evidence from Cassini's final orbits suggests an age of 100 to 400 million years, far less than Saturn itself. The leading theory is that a small icy moon was tidally disrupted by Saturn relatively recently and the debris settled into the equatorial plane.

The planet itself is a slightly smaller, slightly less dense Jupiter — gas giant chemistry, hexagonal storm systems at the north pole, and atmospheric bands less visually dramatic than Jupiter's. Saturn's density is less than that of water (0.687 g/cm³), the only planet in the solar system that would float in a sufficiently large bathtub. The Cassini-Huygens mission (2004–2017) revolutionized the field — discovered active geysers on Enceladus, methane lakes on Titan, and the inner workings of the ring system before plunging into the atmosphere to end the mission cleanly.