Planet Saturn: Facts About Saturn’s Rings, Moons & Size
Planet Saturn: Facts About Saturn’s Rings, Moons & Size
By Charles Q.  Choi, Space.com Contributor |
November 17, 2014 10:25pm ET
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Credit: NASA/JPL
Saturn is the sixth planet from the sun and the second largest planet in the solar system. Saturn was the Roman name for Cronus, the lord of the Titans in Greek mythology. Saturn is the root of the English word "Saturday."
Saturn is the farthest planet from Earth visible to the naked human eye, but it is through a telescope that the planet's most outstanding features can be seen: Saturn's rings. Although the other gas giants in the solar system — Jupiter, Uranus and Neptune — also have rings, those of Saturn are without a doubt the most extraordinary.
Physical characteristics of Saturn
Saturn is a gas giant made up mostly of hydrogen and helium . Saturn is big enough to hold more than 760 Earths, and is more massive than any other planet except Jupiter, roughly 95 times Earth's mass. However, Saturn has the lowest density of all the planets, and is the only one less dense than water — if there were a bathtub big enough to hold it, Saturn would float.
The yellow and gold bands seen in Saturn's atmosphere are the result of super-fast winds in the upper atmosphere, which can reach up to 1,100 mph (1,800 km/h) around its equator, combined with heat rising from the planet's interior.
Saturn spins faster than any other planet except Jupiter, completing a rotation roughly every 10-and-a-half hours. This rapid spinning causes Saturn to bulge at its equator and flatten at its poles — the planet is 8,000 miles (13,000 kilometers) wider at its equator than between the poles.
Saturn's most recent curiosity may be the giant hexagon circling its north pole, with each of its sides nearly 7,500 miles (12,500 km) across — big enough to fit nearly four Earths inside. Thermal images show it reaches some 60 miles (100 km) down into the planet's atmosphere. It remains uncertain what causes it.
Other titanic storms appear in Saturn’s atmosphere once every Saturn year (approximately 30 Earth-years), disrupting the temperature and winds of the planet’s skies. Six such storms have been observed on the planet since 1876, but in 2011, NASA’s Cassini spacecraft became the first orbiter to observe one.
Like other giant planets, Saturn also has northern and southern lights , caused by particles from the sun.
Composition & structure
Atmospheric composition (by volume): 96.3 percent molecular hydrogen, 3.25 percent helium, minor amounts of methane, ammonia, hydrogen deuteride, ethane, ammonia ice aerosols, water ice aerosols, ammonia hydrosulfide aerosols
Magnetic field: Saturn has a magnetic field about 578 times more powerful than Earth's.
Chemical composition: Saturn seems to have a hot solid inner core of iron and rocky material surrounded by an outer core probably composed of ammonia, methane, and water. Next is a layer of highly compressed, liquid metallic hydrogen, followed by a region of viscous hydrogen and helium. This hydrogen and helium becomes gaseous near the planet's surface and merges with its atmosphere.
Internal structure: Saturn seems to have a core between about 10 to 20 times as massive as Earth.
Orbit & rotation
Average distance from the sun: 885,904,700 miles (1,426,725,400 km). By comparison: 9.53707 times that of Earth.
Perihelion (closest approach to sun): 838,519,000 miles (1,349,467,000 km). By comparison: 9.177 times that of Earth.
Aphelion (farthest distance from sun): 934,530,000 miles (1,503,983,000 km). By comparison: 9.886 times that of Earth.
Saturn's moons
Saturn has at least 62 moons . Since the planet was named after Cronus, lord of the Titans in Greek mythology, most of Saturn's moons are named after other Titans, their descendants, as well as after giants from Gallic, Inuit and Norse myths.
Saturn's largest moon, Titan , is slightly larger than Mercury, and is the second-largest moon in the solar system behind Jupiter's moon Ganymede. ( Earth's moon is the fifth largest.) Titan is veiled under a very thick, nitrogen-rich atmosphere that might be like what Earth's was long ago, before life. While the Earth's atmosphere extends only about 37 miles (60 km) into space, Titan's reaches nearly 10 times as far. The atmosphere contains a number of hydrocarbons, chemicals that primarily make up fossil fuels on Earth. Methane rain falls from the sky and moves through the moon’s icy crust . A recent study detected propylene , a chemical used to make plastics, in the planet’s atmosphere.
These moons can possess bizarre features. Pan and Atlas are shaped like flying saucers, Iapetus has one side as bright as snow and one side as dark as coal. Enceladus shows evidence of "ice volcanism," spewing out water and other chemicals from the 101 geysers spotted at the moon’s southern pole. A number of these satellites, such as Prometheus and Pandora, are shepherd moons , interacting with ring material to keep rings in their orbits.
Though scientists have identified many moons, the chaotic system has other small moons constantly being created and destroyed .