Saturn's orbit and the length of its year

Updated October 19, 2026 · 5 min read

A year on Saturn lasts about 29.46 Earth years, or 10,759 Earth days: that is how long the planet takes to complete one orbit around the Sun. Saturn's average distance from the Sun is 9.54 astronomical units, about 1.43 billion km (890 million miles), and because its orbit is slightly elliptical that distance varies between roughly 1.35 and 1.51 billion km.

Saturn's distance from the Sun

Saturn is the sixth planet from the Sun, about twice as far out as Jupiter (5.2 AU) and half as far as Uranus (19.2 AU). Its mean distance of 9.54 AU means sunlight, which reaches Earth in about 8 minutes, needs roughly 80 minutes to get to Saturn. Seen from there, the Sun is a dazzling point about a tenth of the width it appears from Earth, delivering about 1% of the light and heat per square metre, roughly 15 watts against Earth's 1,361.

That weak sunlight shapes almost everything about the planet's upper atmosphere: cloud-top temperatures around -140 °C, chemistry driven by faint ultraviolet light, and seasons that unfold slowly. See atmosphere and temperature.

An almost circular ellipse

Like every planet, Saturn follows an ellipse with the Sun at one focus. Its eccentricity of 0.054 is modest, slightly larger than Jupiter's (0.049) and much larger than Earth's (0.017). In practice:

• At perihelion, its closest point, Saturn is about 1.35 billion km (9.0 AU) from the Sun.
• At aphelion, its farthest point, it is about 1.51 billion km (10.1 AU) away.

The difference, about 160 million km, is more than the distance between Earth and the Sun. At perihelion Saturn receives about 25% more sunlight than at aphelion. Saturn last passed perihelion in 2003 and aphelion in 2018; the next perihelion falls around 2032. Because perihelion happens to come close to the southern summer solstice, southern summers are a little more intense than northern ones, an asymmetry Cassini researchers had to account for when comparing the two hemispheres. Seasonal effects are described on the seasons page.

The orbit is also tilted by about 2.5° relative to the ecliptic, the plane of Earth's orbit. This is why Saturn never strays far from the zodiac constellations in our sky.

How long is a year on Saturn?

One sidereal orbit, measured against the distant stars, takes 29.46 Earth years. This value follows directly from Kepler's third law: the square of the period in years equals the cube of the semi-major axis in AU, and 9.54 cubed is about 868, whose square root is about 29.5.

Some ways to picture that span:

• Since Galileo first observed Saturn in 1610, it has gone around the Sun only about 14 times.
• A person aged 30 has lived roughly one Saturnian year. This return of Saturn to the same position in the sky is the astronomical basis of the astrological Saturn return.
• Because a Saturn day lasts only about 10.5 hours, one Saturnian year contains around 24,000 Saturnian days.
• Each of its four seasons lasts about 7.4 Earth years.

Saturn takes about 2.5 years to cross each constellation of the zodiac. Combined with Earth's own motion, this produces an opposition every 378 days, the planet's synodic period, as Earth catches up with it a little later each year. See distance from Earth.

Orbital speed

Saturn moves along its orbit at an average 9.7 km/s, about 35,000 km/h, roughly a third of Earth's 29.8 km/s. Following Kepler's second law, it speeds up near perihelion (about 10.2 km/s) and slows near aphelion (about 9.1 km/s). The slower pace and the much longer path, about 9 billion km per circuit, together account for the long year.

Saturn and Jupiter: a near-resonance

Saturn's period is close to two and a half times Jupiter's 11.86 years, so five Jupiter orbits nearly equal two Saturn orbits. This near 5:2 commensurability makes the two giants tug on each other in a slowly repeating pattern, producing small wobbles in both orbits with a period of about 900 years, known historically as the "great inequality". Explaining it was one of the triumphs of Pierre-Simon Laplace's celestial mechanics in the 1780s.

On much longer timescales, the relationship between the two giants may have been decisive. Models such as the Nice model and the Grand Tack propose that Jupiter and Saturn migrated in the young solar system, and that a passage through a mutual resonance reshaped the orbits of the other planets and scattered countless small bodies. See how Saturn formed. The meeting of the two planets in our sky, every 20 years or so, is the great conjunction.

Sources

• NASA NSSDCA: Saturn Fact Sheet
• NASA Science: Saturn facts
• NASA JPL Solar System Dynamics: planetary orbital elements
• Laplace, P.-S., Théorie de Jupiter et de Saturne, Mémoires de l'Académie royale des sciences (1785–1786)