Interesting Facts About Saturn
Written by Fraser Cain
Think you know everything about Saturn? Think again. Here are 10 interesting facts about Saturn, and some you probably didn't know.
1. Saturn is the least dense planet in the Solar System
Saturn has a density of 0.687 grams/cubic centimeter. Just for comparison, water is 1 g/cm3 and the Earth is 5.52. Since Saturn is less dense than water, it would actually float like an apple if you could find a pool large enough.
2. Saturn is a flattened ball
Saturn spins so quickly on its axis that the planet flattens itself out. While the distance from the center to the poles is 54,000 km, the distance from the center to the equator is 60,300 km. In other words, locations on the equator are approximately 6,300 km more distant from the center than the poles.
3. The first astronomers thought the rings were moons.
When Galileo first turned his rudimentary telescope on Saturn in 1610, he could see Saturn and its rings, but he didn't know what he was looking at. He though that the rings might actually be two large moons stuck to either side of Saturn. It wasn't until Cristian Huygens used a better telescope to realize that Saturn actually had its famous rings.
4. Saturn has only been visited 4 times by spacecraft
Only 4 spacecraft sent from Earth have ever visited Saturn, and three of these were just brief flybys. The first was Pioneer 11, in 1979, which flew within 20,000 km of Saturn. Next came Voyager 1 in 1980, and then Voyager 2 in 1981. It wasn't until Cassini's arrival in 2004 that a spacecraft actually went into orbit around Saturn and captured photographs of the planet and its rings and moons.
5. Saturn has 60 moons
Jupiter has 63 discovered moons, but Saturn is a close second with 60. Some of these are large, like Titan, the second largest moon in the Solar System. But most are tiny – just a few km across. In fact, the last 4 were discovered by NASA's Cassini orbiter just a few years ago. More will probably be discovered in the coming years.
6. How long is a day on Saturn is a mystery
Determining the rotation speed of Saturn was actually very difficult to do. The planet doesn't have a solid surface, so it's not like you can watch to see how long it takes for a specific crater to rotate back into view. To determine the rotational speed of Saturn, astronomers have to measure the rotation of the planet's magnetic field. By one measurement, Saturn takes 10 hours and 14 minutes to turn on its orbit, but when Cassini approached Saturn, it clocked the rotation at 10 hours and 45 minutes. Astronomers now agree on an average day of 10 hours, 32 minutes and 35 seconds.
7. Saturn's rings could be old, or they could be young.
It's possible that Saturn's rings have been around since the beginning of the Solar System – almost 4.6 billion years ago. They have been created when a 300 km ice moon was torn apart by Saturn's gravity, and formed a ring around the planet. It's also possible that they're the left over material when Saturn formed in the solar nebula. But astronomers have also found that the ring material looks just too clean to have formed so long ago, and could be as young as 100 million years old. It's all just a big mystery.
8. Sometimes the rings disappear
Well, they don't actually disappear, but they look like they're going away. Saturn's axis is tilted, just like Earth. From our point of view, we see Saturn's changing position as it takes its 30 year journey around the Sun. Sometimes, the rings are fully open, and we see them in all their glory, but other times we see the rings edge on – it looks like they've disappeared. This will happen in 2008-2009, and then again in 2024-2025.
9. You can see Saturn with your own eyes
Saturn appears as one of the 5 planets visible with the unaided eye. If Saturn is in the sky at night, you can head outside and see it. To see the rings and the ball of the planet itself, you'll want to peer through a telescope. But you can amaze your friends and family by pointing out that bright star in the sky, and let them know they're looking at Saturn.
10. There could be life near Saturn
Not life on Saturn; the planet is way too hostile to support life. But there could be life on one of Saturn's moons: Enceladus. NASA's Cassini spacecraft recently discovered ice geysers blasting out of Enceladus' southern pole. This means that some process is keep the moon warm enough that water can remain a liquid. And wherever we find liquid water on Earth, we find life.
I hope you enjoyed these interesting facts about Saturn.
We have recorded two episodes of Astronomy Cast just about Saturn. The first is Episode 59: Saturn, and the second is Episode 61: Saturn's Moons.
Filed under: Astronomy
