Solar System

Saturn

Gas giant · The ringed jewel · Known since antiquity (rings first seen by Huygens, 1655)

Famous for its brilliant rings of ice and rock, Saturn is the second-largest planet and the least dense — it would float in water if a bath were big enough.

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Texture: Solar System Scope (CC BY 4.0)

Key facts

Distance from Sun 9.54AU 1.43 billion km
Radius 58,232km 9.1× Earth
Mean temperature −140°C cloud-top average

Time & motion

A day (one spin) 10.7 hours Short days, like the other giants.
A year (one orbit) 29.4 Earth years A single Saturnian year spans almost three Earth decades.
Surface gravity vs Earth
9.0 m/s² 0.92 g
0Earth = 1 g2.5×

Mass & physical characteristics

Mass 5.68 × 10²⁶kg 95.2× Earth
Density 0.69g/cm³ Water = 1.0 g/cm³
Escape velocity 35.5km/s Speed to break free
Orbital velocity 9.7km/s Speed around the Sun
Axial tilt 26.7° An Earth-like tilt that tips its rings toward and away from us.

Atmosphere & magnetosphere

Atmosphere

About 96% hydrogen and 3% helium, with traces of methane and ammonia. Fierce equatorial winds reach roughly 1,800 km/h.

Magnetic field

A strong field, unusually well aligned with the planet's rotation axis.

Moons & rings

Known moons 293 293 confirmed moons — the most of any planet, including Titan.
Notable moons
TitanEnceladusRheaIapetusMimas

Rings

The brightest rings in the Solar System — mostly water ice, split by the Cassini Division.

Make-up

Composition

Hydrogen and helium; spectacular rings of ice, dust and rock.

Notable features

  • The bright ring system, spanning about 280,000 km yet only tens of metres thick.
  • A six-sided polar jet stream — Saturn's 'hexagon'.

Fun facts

  • Saturn is the least dense planet — it would float in water if you had a big enough bath.
  • Its rings are made mostly of water ice and may be only 100–200 million years old.
  • The moon Titan has a thick atmosphere and lakes of liquid methane.
  • Enceladus shoots geysers of water ice into space from a hidden ocean.
  • A persistent six-sided jet stream circles Saturn's north pole.

Exploration

Pioneer 11 1979 First spacecraft to fly past Saturn.
Voyager 1 & 2 1980–81 Detailed the rings and hazy Titan.
Cassini–Huygens 2004–17 Orbited Saturn; landed a probe on Titan.