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Top Ten Facts About Saturn
10. Saturn is the least dense planet in our solar system.
All of the jovian, or outer, planets are naturally less dense than are the terrestrial, or inner, planets. This is due to their composition, which is a result of their distance from the Sun. Nearer to the Sun, temperatures are suitable for the condensation of rock and metal--we can attest to that, with our rocky planet and iron core. Farther from the Sun, however, temperatures are so cold that instead it's ice and gas that condense. Saturn is largely composed of hydrogen and helium, which condense at -434º and -452º Fahrenheit (respectively).
So when the solar system was forming, all of the aforementioned materials were in their respective locations—rock and metal close to the Sun, ice and gas farther away. Over time, the bits and pieces in each location grew larger from slamming into each other and building up (through a process called accretion).
While Earth's density is 5514 kg/m^3, Saturn's is only 687 kg/m^3—Earth is just over eight times denser than Saturn! That may not be so impressive though, considering even water is denser than Saturn. That means that if our solar system was filled with water, Saturn would float atop it.
9. The temperature at surface-level on Saturn is -220 degrees Fahrenheit.
Saturn is situated a chilly 891 million miles from the Sun—that's almost ten times farther away than the Earth! While that's the primary reason Saturn is so cold, it's also because of Saturn's thin atmosphere. For a comparison of Earth's and Saturn's temperatures, imagine this: there's a person standing close to a fire and another standing much farther away. Now imagine that the person nearer to the fire is wearing a jacket—but the person farther away isn't even wearing pants.
The interior of Saturn is believed to be hot, due in part to the fact that Saturn is radiating more heat than it's getting from the Sun—the heat energy coming from Saturn can't be limited to heat reflected from the Sun.
8. Gravity on Saturn isn't much stronger than gravity on Earth.
Even though Saturn is huge, it isn't very dense. Also because it is so huge, the surface-level (since it hasn't a solid surface) is much farther from the center of the planet. The two factors that determine an object's gravitational force exerted on another object are mass and distance. Saturn isn't as massive as it looks, because of its aforementioned low density, and the surface-level is far from the center because Saturn is so big. As a result, Saturn's gravity isn't that much stronger than Earth's. If you could stand at the surface-level of Saturn, you would weigh only 6% more than you do on Earth. For a 150 pound person, his or her Saturn weight would be only nine pounds more.
7. On Saturn, a day is only 10.5 hours and a year is about 30 Earth years long.
All of the jovian planets spin much more quickly than the terrestrial planets do. This has shaped them into what are called oblate spheroids (they look like a ball that's been squished a little on the top and bottom). The planets are all this way somewhat, due to gravitational and rotational factors, but the jovian planets are to a more exaggerated degree. One reason for this is that they are rotating more quickly than the terrestrial planets are. It takes Saturn just 10.5 hours to make one complete rotation.
Saturn takes much longer to orbit the Sun than Earth does. That makes sense, because it's so much farther away; it has a lot more distance to cover. Its distance affects its orbital speed in another way, however. The planets don't all travel at the same speed as they orbit the Sun. The closer a planet is to the Sun, the faster it's moving through space (compare Mercury's speed of around 54 billion mph with Neptune's 6.5 billion mph—that's a big difference!). This is explained in Kepler's third law of planetary motion. The farther a planet is from the Sun the less gravitational pull the Sun exerts on it, so the slower it moves through space. Saturn travels at around 11 billion mph, and its year lasts about 30 Earth years.
6. Saturn experiences winds up to 1100 miles per hour.
On Earth, our worst hurricanes feature winds up to "only" 250 miles per hour. Saturn's wind is so much stronger due to a combination of factors including composition, density, gravity, and of course its high rotational speed. In addition, the workings of the interior of the planet may play a role. Lori Stiles (Space Daily) says that the giant storms that Saturn and other outer planets experience "are clues to what's going on deeper inside giant gas planets to fuel the jet winds that dominate atmospheres such as those belonging to Jupiter and Saturn." Relatively little is known about these planets' interiors, so the mystery remains.
5. Saturn has a magnetic field that is much stronger than Earth's.
Saturn's strong magnetic field (also called a magnetosphere) produces brilliant auroras, as featured in the above video by the NASA Jet Propulsion Laboratory. These auroras are caused when high energy solar particles interact with Saturn's magnetic field, which is 578 times stronger than Earth's.
Saturn's magnetic field was actually very helpful in determining the length of its day. Since it doesn't have a solid surface, astronomers couldn't simply watch it for long enough to see when the same side would come back around. The use of magnetic field information to determine rotational period was successful with Jupiter, but with Saturn it was more difficult, owing to explosions of hot plasma affecting the magnetic field.
Convection is thought to be the driving force behind Saturn's magnetic field, which is created deep within the planet. The condensation of helium near Saturn's core gives off heat. The heat energy powers convection, which in turn powers the magnetic field. This is not certain, however. Many mysteries remain in our understanding of the physics of planetary magnetic fields.
4. Saturn has an extensive ring system composed of ice, rocks, & dust.
Discovered in 1610 by Galileo, Saturn's ring system is its best known feature. It is made up of millions upon millions of individual pieces, of the same composition as the ring systems of the other jovian planets. Saturn's rings stand out because they are so much larger, and there's a great deal more material in them than in the other planets' rings. The particles range in size from smaller than a grain of sand to larger than a mansion. It is believed that they formed from asteroids, comets, or shattered moons.
3. Saturn has over 50 moons.
Of Saturn's moons, there are 53 that are named. There are an additional nine that are unnamed, which are known as provisional moons. They haven't been named yet because their discovery has to be confirmed.
Saturn's first moon to be discovered was Titan, in 1655 by Christiaan Huygens. Among the most interesting of Saturn's moons, Titan has an atmosphere that, like ours, is composed primarily of nitrogen. Titan also features lakes and rivers—but instead of being filled with water, they're filled with methane and ethane.
Enceladus is another of Saturn's interesting moons. Near its south pole, it has jets that spew out ice and water vapor. The surface is covered with ice, but astronomers believe that miles beneath it lies an ocean of water.
2. Saturn's name is derived from Roman mythology.
In Roman mythology, Saturn was the name of the god of agriculture. In the stories, he feared his children would someday overthrow him as a ruler—so he ate them. Fearing she would lose another son, his wife swaddled a rock and pretended it was their child. When Saturn ate the rock (thinking it was his child), it forced out all of the other children he had eaten. Jupiter eventually conquered his father, who clearly deserved it.
1. The primary missions that have studied Saturn are Cassini, Voyager 1&2 and Pioneer 11.
The first visit to Saturn took place in 1979. Pioneer 11 executed a flyby, from which we obtained a series of low-res photos, information on the rings, and temperature measurements. Just one year later there was another Saturn flyby—this time by Voyager 1. It sent us high-res photos, from which we were able to learn much more about Saturn's surface, as well as its moons and rings. Less than a year after that, Voyager 2 followed suit. Additional photos were obtained, as were readings of Saturn's atmospheric density and temperature, and we discovered more moons and gaps in the rings.
More recently, the Cassini-Huygens spacecraft was launched into orbit around Saturn. From there, the Huygens probe was released to land on the surface of Titan. This event is illustrated in an artist's rendering above. Cassini's mission has been extended twice, and is currently scheduled to continue through September of 2017. Much of what we know about Saturn is a result of this mission. Who knows what we'll discover next!
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Special thank you to Jacob Balzer for research and information gathering!
http://solarsystem.nasa.gov/planets/profile.cfm?Display=Sats&Object=Saturn http://www.nasa.gov/mission_pages/cassini/whycassini/plasma20101214.html http://science.nasa.gov/missions/cassini/