Saturn vs Jupiter, the two gas giants compared

Updated October 19, 2026 · 6 min read

Jupiter and Saturn are both gas giants made mostly of hydrogen and helium, but Jupiter is about 3.3 times more massive while being only about 19% wider. Saturn is far less dense, more flattened, colder and twice as far from the Sun, and it has a spectacular ring system where Jupiter has only faint dusty rings. Saturn also has many more known moons: 274 confirmed, against fewer than a hundred for Jupiter.

Comparison table

Values from NASA fact sheets; rotation periods are the system III-type rates for Jupiter and the 2019 ring-seismology estimate for Saturn (see day length).

Size and mass: why Jupiter isn't much bigger

Jupiter has more than three times Saturn's mass but is only about a fifth larger in diameter. Adding mass to a hydrogen planet mostly compresses it rather than inflating it. This is why Jupiter is almost twice as dense as Saturn, and why a planet a few times more massive than Jupiter would be about the same size or even slightly smaller. Saturn, less compressed, holds the record for the lowest density of any planet and the strongest flattening, its fast spin bulging its light outer layers. For Saturn's dimensions in detail, see size and mass.

Interiors: helium rain and fuzzy cores

Both planets are thought to have the same basic structure: an outer envelope of molecular hydrogen, a deep layer of metallic hydrogen that generates their magnetic fields, and a central region enriched in rock and ice. Two findings stand out:

• Fuzzy cores. Juno's gravity data for Jupiter and Cassini's ring seismology for Saturn both point to diffuse cores, where heavy elements are spread over a large fraction of the radius rather than forming a compact ball (see interior).
• Helium rain. Saturn's upper atmosphere is more depleted in helium than Jupiter's. Because Saturn is colder inside, helium separates from metallic hydrogen more readily and rains toward the center, releasing heat. This helps explain why Saturn, though smaller, has a relatively strong internal heat source (see temperature).

Atmospheres and weather

Both planets show bands of clouds driven by alternating jet streams. Jupiter's are high-contrast, with white ammonia zones and brown belts; Saturn's look muted because a thicker layer of haze covers its colder, more extended atmosphere, giving its pale butterscotch color.

Saturn's winds are stronger: up to about 1,800 km/h (500 m/s) at the equator, roughly three to four times the speed of Jupiter's equatorial jet. Jupiter has the Great Red Spot, a storm observed for at least 190 years; Saturn instead produces Great White Spots, huge storms that erupt roughly once per Saturn year, and has its unique polar hexagon.

Rings

All four giant planets have rings, but they could hardly be more different. Saturn's main rings are broad, bright and made of over 95% water ice, with a total mass around 1.5 × 10¹⁹ kg. Jupiter's rings, discovered by Voyager 1 in 1979, are thin, dark and made of fine dust knocked off its small inner moons. Why Saturn has such massive icy rings, and whether they are young, remains debated (see age of the rings).

Moons

Jupiter's four Galilean moons, discovered by Galileo in 1610, include three large worlds comparable to or bigger than our Moon, plus volcanic Io. Saturn has a single giant, Titan, slightly smaller than Ganymede but with a thick nitrogen atmosphere, along with a family of mid-sized icy moons such as Enceladus. The moon count has see-sawed between the two: after surveys announced in 2023 and March 2025, Saturn now leads clearly, with 274 confirmed moons, most of them small irregular bodies a few kilometers across.

Magnetic fields and radiation

Jupiter's magnetic field is the strongest of any planet, about 20,000 times Earth's in total magnetic moment, and its radiation belts are lethal to unshielded electronics. Saturn's field is about 580 times Earth's in magnetic moment, but at the cloud tops it is slightly weaker than Earth's surface field, and its radiation environment is much milder. Saturn's field is also unusually well aligned with its spin axis, a puzzle for dynamo theory (see magnetosphere).

Orbits and their relationship

Jupiter orbits the Sun about 2.5 times for every Saturn orbit. This near 5:2 ratio produces the "great inequality", a long-period perturbation of both orbits explained by Pierre-Simon Laplace in the 1780s. Every 19.9 years or so, the two planets line up in the sky in a great conjunction; the 2020 event brought them within 0.1° of each other. Early in the solar system, their gravitational interplay may have shaped the inner planets and the asteroid belt (see formation).

Exploration

Jupiter has been studied by orbiters Galileo (1995–2003) and Juno (since 2016), with ESA's JUICE and NASA's Europa Clipper en route. Saturn had one orbiter, Cassini (2004–2017), plus the Huygens lander on Titan; the next mission, Dragonfly, targets Titan rather than the planet.

Sources

• NASA Goddard: Jupiter Fact Sheet
• NASA Goddard: Saturn Fact Sheet
• NASA Science: Jupiter
• NASA Science: Saturn