Saturn, the ringed gas giant

Updated October 19, 2026 · 5 min read

Saturn is the sixth planet from the Sun and the second largest in the solar system, a gas giant made mostly of hydrogen and helium with no solid surface. It is about 9.5 times wider than Earth and 95 times more massive, yet its mean density is lower than that of water. It orbits the Sun every 29.5 years at an average distance of 1.43 billion km (890 million miles).

A planet defined by extremes

Saturn's numbers are easier to grasp side by side. Its equatorial diameter of 120,536 km would line up nine and a half Earths, and its volume could hold about 764 of them. But because it is made almost entirely of the two lightest elements, its mass is "only" 95 Earth masses, and its average density of 0.687 g/cm³ is the lowest of any planet. The details, and the fair answer to the old question of whether Saturn would float in a bathtub, are on the pages about size and mass and density.

Saturn also spins faster than any planet except Jupiter. A day lasts roughly 10 hours 33 minutes, a figure that was surprisingly hard to pin down because there is no surface to watch rotate; how scientists finally measured it using waves in the rings is explained on the day length page. That rapid spin flattens the planet visibly: the polar diameter is almost 12,000 km shorter than the equatorial one, close to the width of an entire Earth.

Orbit, distance and seasons

At 9.54 astronomical units from the Sun, Saturn receives about one ninetieth of the sunlight that reaches Earth. Its slightly elliptical orbit takes it between roughly 1.35 and 1.51 billion km from the Sun, and its distance from Earth swings between about 1.2 and 1.66 billion km depending on where both planets are. Light needs well over an hour to make the trip, which is why spacecraft at Saturn have always operated autonomously.

Because its axis is tilted by 26.73°, a little more than Earth's 23.4°, Saturn has seasons, each lasting about 7.4 years. The most recent equinox, in May 2025, came shortly after the rings appeared edge-on from Earth in March 2025.

Clouds, colors and weather

What we see of Saturn is the top of a deep atmosphere of hydrogen and helium, capped by ammonia-ice clouds and a high photochemical haze. That haze softens the banding and gives the planet its muted pale-gold color, far less contrasted than Jupiter's. Underneath, the weather is violent: equatorial winds reach about 1,800 km/h (1,100 mph), and roughly once per Saturnian year a giant convective storm erupts and wraps around an entire hemisphere, as it did in 2010–2011.

At the north pole sits one of the strangest structures in the solar system, the hexagon, a six-sided jet stream about 29,000 km across that has persisted at least since Voyager photographed it in 1980–1981.

Inside Saturn

Below the clouds, pressure and temperature climb until hydrogen turns into an electrically conducting metallic fluid. Ring seismology suggests that the core is not a compact ball but a diffuse region of rock, ice and hydrogen extending over more than half of the planet's radius. Saturn radiates about 2.5 times more energy than it receives from the Sun, probably because helium separates from hydrogen and sinks like rain, releasing gravitational energy; the consequences for temperature are explored separately. Some models also predict carbon forming solid grains deep down, the basis of the popular diamond rain idea.

The metallic hydrogen layer generates a magnetic field that is unusual for being almost perfectly aligned with the spin axis. It carves out a vast magnetosphere filled with water ions from the geysers of Enceladus, and lights up ultraviolet and infrared auroras around both poles.

Comparisons and context

Saturn is often described as Jupiter's smaller sibling, and the Saturn vs Jupiter comparison shows where that holds and where it breaks down. The Saturn vs Earth page puts our own planet to scale, while formation covers how a core of ice and rock may have gathered a gas envelope in the first few million years of the solar system. For readers who want the essentials in one place, the facts page collects the key numbers in a single table.

The planet is inseparable from its rings and its retinue of moons, and almost everything we know in detail comes from four spacecraft, above all Cassini–Huygens, which orbited Saturn from 2004 to 2017.

Sources

• NASA Science: Saturn
• NASA NSSDCA: Saturn Fact Sheet
• Mankovich, C. et al. (2019), "Cassini Ring Seismology as a Probe of Saturn's Interior", The Astrophysical Journal 871:1
• NASA Science: Cassini mission