Saturn 101 | National Geographic

• [Instructor] With its gold color and stunning rings, Saturn is quite a planetary gem.

Saturn is the second-largest of the eight planets, and it is about ten times as wide as Earth. Despite its size, Saturn is actually the lightest planet. It is predominantly made of the gases hydrogen and helium. And because of its particular gaseous composition, Saturn is the only planet in the solar system that's less dense than water. If the planet were placed on an enormous ocean, it would be able to float.

Saturn's gaseous makeup also means that it has no true surface. At its center, the planet has a dense core of water, ice, and rocky material, but it has no actual landmass. Instead, it's mostly made of gases, liquids, and yellow ammonia crystals that swirl around the planet, creating golden clouds and storms. The largest storm on Saturn is at its north pole. It's over twice the size of Earth and shaped in a near-perfect hexagon. Each of the six sides is believed to be the result of jet streams, which all encircle a massive hurricane.

Because of Saturn's inhospitable environment, the planet cannot support life - but some of its moons might. Saturn has more than 50 confirmed moons, and each varies in size and terrain. Enceladus, one of Saturn's smallest moons, is covered in ice and only about as wide as the state of Pennsylvania. Titan, Saturn's largest moon, is nearly as wide as Canada. Titan is also the only moon in the solar system with clouds and a dense atmosphere. Both Titan and Enceladus have underground oceans that would make them potentially capable of sustaining life.

Saturn's moons may also play a role in shaping the planet's signature feature: its rings. Saturn's ring system is the largest and most complex in the entire solar system. The rings are made of icy and rocky remnants from comets, asteroids, and moons. The particles range in size from being as small as dust to as big as mountains. The ring system is divided into seven groups of rings. Altogether, they are as wide as four-and-a-half Earths, but only about two-thirds of a mile thick.

How the rings are able to stay on track and intact has to do with Saturn's smallest moons. Called Shepherding moons, these tiny satellites orbit between the rings, and they seem to use their gravity to shape the ring material into circular paths. Saturn has fascinated scientists and amateur astronomers alike for thousands of years.

The ancient Greeks and Romans, who named the planet after their god of agriculture, believed it was a star. It wasn't until the 17th century, after the telescope was invented, that scientists like Galileo Galilei, Christiaan Huygens, and Giovanni Cassini could take a much closer look. Only then was Saturn's planetary status discovered and, ultimately, its many moons and brilliant rings. Because of its planet-like moons, lightweight composition, and dazzling ring system, Saturn continues to mesmerize us to this day.