Saturn

Although all four giant gas planets in the outer solar system are surrounded not only by moons but also by rings of varying prominence, Saturn is considered “the” ringed planet. Unlike the rings of Uranus and Neptune, which are more difficult to observe, Saturn’s rings are so distinctive that the famous astronomer Galileo Galilei discovered them over 400 years ago using his simple, homemade telescope. The rings are disk-shaped accumulations of countless solid particles ranging in size from dust grains to several meters in diameter.

 

With a diameter of 120,000 kilometers and a mass 95 times that of Earth, Saturn is the second-largest planet in the solar system. It is the planet farthest from the Sun that is visible to the naked eye and has therefore been known since ancient times. To the Romans, Saturn was the god of agriculture and was identified with Cronus, a Titan from Greek mythology.

At 10 hours and 40 minutes, Saturn takes only 45 minutes longer than Jupiter to complete one rotation on its axis. Its orbital period around the Sun, at 29.5 years, is about two and a half times as long as Jupiter’s (11.9 years).

Like all gas giants, Saturn has no solid surface. The outer layers of its atmosphere consist of hydrogen (93%) and helium (7%), with small amounts of methane and ammonia. At temperatures ranging from minus 140°C to minus 190°C, storms rage through the atmosphere at speeds of up to 1,600 kilometers per hour. As on Jupiter, a stationary, permanent hurricane with a diameter of 8,000 kilometers can be observed on Saturn.

To date (2026), 285 of Saturn’s moons are known. The largest (Titan), at 5,150 km, is about 1.5 times the size of Earth’s moon.

Data Overview

Data Overview

Surface

Gas Planet

Number of moons

285 (2026)

Mass

95.2 Earth masses

Diameter

120,536 km (Model: 26.8 mm)

Distance from the Sun
  • At perihelion: 1,352 million km
    (model: 300.6 m)
  • At aphelion: 1,514 million km
    (model: 336.4 m)
Turnaround time

29 years, 167 days

Distance traveled in 24 hours
  • At perihelion: 881,000 km
    (Model: 20 cm)
  • At aphelion: 789,000 km
    (Model: 18 cm)
Rotation Duration

10 hours, 40 minutes

Rotation Axis Tilt

26.73 degrees

Direction of rotation

clockwise (like a train loop)

Average Energy Irradiance

14 watts per square meter

Mean Solar Angular Diameter

0.10 degrees

Temperature

-139 °C

Atmosphere
  • 96.3% hydrogen (H₂)
  • 3.25% helium (He)
  • 0.45% methane (CH₄)
Weather

windy planet

First Probe Mission

1979 Pioneer 11 Space Probe (U.S.)