Named after the Roman god of agriculture, Saturn is the second largest planet and the sixth in distance from the Sun. It’s also the furthest planet visible with the naked eye and has been known since prehistoric times. Galileo was the first person to observe Saturn through a telescope in 1610. He reported seeing odd appendages on either side of Saturn; he did not realize he was viewing Saturn’s rings.

It takes Saturn a little over 29 years to make one revolution around the Sun. The planet also rotates extremely fast and completes a rotation of its axis in about 10 hours.  This rapid rotation causes Saturn to flatten at its poles and bulge at the equator. Saturn’s equatorial diameter is 74,898 miles. In comparison, its polar diameter is only (67,560 miles, or 10 percent smaller, which makes Saturn the most oblate of all the planets in the solar system. Saturn has the lowest density of any planet, even lower than the density of water, meaning it would float on a body of water large enough to hold it.

One of the four gas giants, Saturn’s atmosphere is very similar to that of Jupiter’s. It is mainly comprised of hydrogen with lesser amounts of helium and much lesser quantities of methane and ammonia. It is thought that Saturn’s atmosphere contains more sulfur than Jupiter’s, explaining the planet’s yellowish hue. It is also much colder than Jupiter due to it being further from the Sun, with an average temperature of about -285 degrees F.  Wind speeds on Saturn are extremely high, having been measured at slightly more than 1,000 mph, considerably higher than Jupiter. Saturn’s axis is tilted about 27 degrees to the perpendicular of the orbital plane, meaning that the planet experiences Earth-like seasons.

A large white spot has been detected in the equatorial regions of Saturn’s atmosphere thought to be a gigantic storm. Called Great White Spot, the phenomenon was first observed in 1876. The storm is caused by convection currents from the planet’s interior dragging water, ammonia and other molecules above the cloud tops where the temperature is much cooler, causing them to freeze, forming white clouds. The giant storms occur about once every 30 Earth years, one Saturnian year. The last storm occurred in 2010 and was captured by the Cassini space probe belonging to the North American and European space agencies. It covered a distance of 10,000 kilometers, or 6,213 miles.

Saturn’s interior is also expected to be very similar to Jupiter’s. As atmospheric hydrogen is placed under increasing pressure, it turns into a liquid. As the liquid is churned about as a result of Saturn’s rapid rotation, a magnetosphere is generated. This liquid metallic hydrogen envelops a rocky core of rock, ice, water, and other compounds made solid by the intense pressure and heat. Saturn’s magnetic field is smaller than Jupiter’s but still 578 times as powerful as Earth’s.

Saturn comes second only to Jupiter in the number of natural satellites it posses. It 1997 only 18 moons have been identified. However, more then twice that amount have been discovered since then. The number currently stands at 53, with more awaiting confirmation. The largest of them, Titan, is the second largest moon in our solar system. With an equatorial radius of 1,600 miles, Titan is bigger than our own Moon and even the planet Mercury. Only Jupiter’s moon Ganymede is larger. Titan is the only satellite in the solar system known to have an atmosphere, consisting of nitrogen and methane and is the most Earth-like object in the solar system.  Recently, the Cassini spacecraft and the European based Huygens probe has confirmed many theories involving Titan, including seeing clouds, evidence of rain, seasonal variations, and even ice volcanoes.

The Rings

Beautiful and mysterious, Saturn’s rings are located in the plane of the planet’s equator. They spread over hundreds of thousands of kilometers, are extremely thin and consist of billions of individual particles of mostly water ice which create waves, wakes and other structures. The rings are thought to be the remnants of a moon that strayed too close to Saturn and was torn apart by tidal forces. Another theory is that the rings comprise debris left over from the planet’s creation. However, the rings are located in the Roche Limit which is the boundary at which it becomes “too close” for a moon to orbit a planet and gets destroyed. This may indicate that they were most likely created by a moon that got too close.

Saturn Facts

  • Only 4 spacecraft sent from Earth has ever visited Saturn
  • On July 1, 2004, the Cassini-Huygens was the first spacecraft to orbit Saturn. Launched on October 15, 1997, it traveled over 2,000,000,000 miles at a speed of 70,700 miles per hour before it reached the ringed planet
  • It is believed that Saturn’s rings will one day disappear. They will either disperse (spread out) into space or get sucked into the planet by its pull of gravity
  • Saturn is twice as far away from the Sun as Jupiter is
  • Saturn’s rings seem to disappear about every 14 years. The rings seem to disappear when Saturn is tilted directly in line with Earth