Saturn

Size, gravity and what’s inside

A volleyball next to Earth’s nickel, squashed by its own spin, light enough to float and with nowhere to stand. Here’s Saturn in numbers.

Sixth from the Sun

Saturn is the sixth planet from the Sun, and the second largest in the solar system. NASA Science: Saturn facts Like Jupiter, Saturn is mostly hydrogen and helium, the same two main ingredients as the Sun. NASA Science: Saturn facts

Saturn took shape about 4.5 billion years ago, with the rest of the solar system, and settled into its present place about 4 billion years ago. NASA Science: Saturn facts

How big?

Saturn is about 120,500 km wide at its equator: 9 times wider than Earth. NASA Science: Saturn facts If Earth were the size of a nickel (a US 5-cent coin), Saturn would be about as big as a volleyball. NASA Science: Saturn facts

Saturn has 95.16 times Earth’s mass, and Earth would fit inside it about 763 times by volume. NASA NSSDC: Saturn fact sheet

Saturn is visibly squashed: 60,268 km from centre to equator but 54,364 km from centre to pole. NASA NSSDC: Saturn fact sheet ESA says Saturn is flattened at the poles because it spins so fast. ESA: Facts about Saturn

Light enough to float

Saturn’s average density is 687 kg per cubic metre. Earth’s is 5,513. NASA NSSDC: Saturn fact sheet Saturn is the only planet whose average density is less than water’s. NASA says it could float in a bathtub, if a bath that big existed. NASA Science: Saturn facts

Test it for yourself: try the Bathtub Test →

How far?

NASA’s Saturn facts page puts Saturn an average 1.4 billion km from the Sun: 9.5 astronomical units (1 AU is the Sun–Earth distance). NASA Science: Saturn facts

ESA gives a mean distance of 1,429,400,000 km, or 9.6 AU. ESA: Facts about Saturn NASA’s fact sheet gives Saturn’s orbit a semimajor axis of 1,432.041 million km. NASA NSSDC: Saturn fact sheet

Sunlight takes 80 minutes to reach Saturn. NASA Science: Saturn facts

Saturn comes as close as 1,205.5 million km to Earth and gets as far as 1,658.6 million km. NASA NSSDC: Saturn fact sheet

Days and years

Saturn has the second-shortest day in the solar system: about 10.7 hours. NASA Science: Saturn facts NASA’s fact sheet gives the length of a Saturn day as 10.656 hours. NASA NSSDC: Saturn fact sheet

One trip round the Sun, a Saturn year, takes 10,755.699 Earth days. NASA NSSDC: Saturn fact sheet That is about 29.4 Earth years. NASA Science: Saturn facts

Saturn is tilted by 26.73 degrees, not far off Earth’s 23.5, so like Earth it has seasons. NASA Science: Saturn facts

How old would you be in Saturn years? Try “You on Saturn” →

Gravity, and nowhere to stand

At Saturn’s 1-bar cloud level, gravity on average is 1.140 times Earth’s. NASA NSSDC: Saturn fact sheet Spin and squash make a difference: gravity is 0.916 times Earth’s at Saturn’s equator and 1.235 times at its poles. NASA NSSDC: Saturn fact sheet

To escape Saturn’s gravity you would need to go 35.5 km a second. NASA NSSDC: Saturn fact sheet

Saturn has no true surface. It is mostly swirling gases, and liquids deeper down. NASA Science: Saturn facts The pressure and heat deep inside would crush, melt and vaporise any spacecraft trying to fly in. NASA Science: Saturn facts

ESA notes a craft could drift down on a parachute and send data until the pressure crushed it. In the end, that was Cassini’s fate. ESA: Facts about Saturn

Air and temperature

Saturn’s atmosphere is 96.3% hydrogen and 3.25% helium, by volume. NASA NSSDC: Saturn fact sheet

At the 1-bar level, Saturn’s air is −139 °C. NASA NSSDC: Saturn fact sheet

Saturn’s clouds show as faint stripes, jet streams and storms, in shades of yellow, brown and grey. NASA Science: Saturn facts

Inside Saturn

At the centre is a dense core of metals like iron and nickel, wrapped in rock, then liquid metallic hydrogen. NASA Science: Saturn facts

A giant magnet

Saturn’s magnetic field is smaller than Jupiter’s but still 578 times as powerful as Earth’s. NASA Science: Saturn facts

Cassini showed some of Saturn’s auroras are driven not by the solar wind but by particles from its moons and the planet’s fast-spinning magnetic field. NASA Science: Saturn facts

Its name

Saturn is named after the Roman god of farming and wealth, who was also the father of Jupiter. NASA Science: Saturn facts Around 400 BCE Greek astronomers named it after Kronos, god of farming. The Romans later swapped in their own god of farming: Saturn. NASA Science: Saturn exploration

The oldest written records of Saturn come from the Assyrians, around 700 BCE, who called it the “Star of Ninib”. NASA Science: Saturn exploration

Saturn is the farthest planet from Earth that was discovered with the unaided eye, and it has been known since ancient times. NASA Science: Saturn facts

Galileo saw the rings through a telescope in July 1610 but took them for a “triple planet”. NASA Science: Saturn exploration ESA: Saturn’s rings At first Galileo wondered if he was looking at three planets, or a planet with handles. NASA Space Place: All about Saturn

Could anything live there?

Saturn itself is a poor place for life, but two of its moons, Enceladus and Titan, have internal oceans and could possibly support it. NASA Science: Saturn facts · checked 27 Oct 2026

Next: the rings →