Saturn is the sixth planet from the Sun and the one with the most moons, orbiting our star at a distance of 1.426 billion kilometers. It is the second largest Solar System planet; a yellow-colored gas giant, like Jupiter, with its yellow coloration is due to ammonia crystals in its upper atmosphere. It is orbited by several rings. Saturn, its rings, and moons are collectively known as the Cronian System.
Originally called Phaenon or Phainon by the Greeks, it was later known as Cronus, the leader of the Titans in Greek mythology; Saturn's moons are named after individual Titans. The Romans knew this deity/planet as Saturn, the name this planet is now commonly called. In Eastern Asian languages it is literally called the "earth/dirt star" (土星).
Saturn has a diameter of 116,464 kilometers, which is around 9 times that of Earth. Inside Saturn is probably a core of iron, nickel, silicon and oxygen compounds, surrounded by a deep layer of metallic hydrogen, then a layer of liquid hydrogen and liquid helium and finally, an outer gaseous layer.
Saturn is 95 Earth masses in mass, but due to its larger volume of ~720 times that of the Earth's, the planet has a very low average density of 0.687 grams per cubic centimeter - the lowest of the planets of our Solar System and less than that of water (1 gram per cubic centimeter). This would mean that if Saturn were put in a large enough body of water with gravity acting towards the bottom, the planet would float on it!
Saturn has the most moons. 82 known moons orbit the planet; 53 of which are officially named. 12 of these were recently discovered in 2019. The largest moon is Titan, which is larger in volume than the planet Mercury. Titan has an atmosphere made of methane, and has lakes on its surface that are made out of liquid Methane as well. Other moons, like Hyperion (diameter 360.3 kilometers) and Phoebe (diameter 218.8 kilometers), have lots of craters and are mostly hollow, and one of them, Mimas (diameter 393.4 kilometers), has a giant crater called Herschel (named after William Herschel) that is 10 kilometers deep. One of the moons, called Rhea (diameter 1,532.4 kilometers), has a system of 3 faint rings. The majority of Saturn's moons are smaller than the Earth's own moon and covered in water ice, and may have underground liquid water mantles.
The first discovered, largest, and round of Saturn were named after Titans in Greek mythology; the largest moon Titan is named after the race/generation as a whole. But since Saturn bears the most satellites, other, smaller, and more recently-discovered satellites are given names of giants hailing from other mythologies such as Norse, Gallic, Scandinavian, and Inuit. Most of these satellites are either captured objects or fragments of much larger bodies; one named Mundilfari (after the father of the sun goddess Sunna and moon deity Mani in Germanic mythology) is believed to be made of fragments of Phoebe (named after a Titaness of the Earth's Moon in Greek mythology), a retrograde-orbiting moon which in turn is believed to be a centaur captured from the Kuiper Belt, similar to Pluto.
Scientists believe that the rings are material left after a moon broke apart after passing through the planet's Roche limit. A new hypothesized theory says that it was a very large moon, which crashed into the planet or another moon. This left a large amount of ice to form the rings, and also some of the moons, like Enceladus (diameter 504,2 kilometers) which are thought to be made of ice. The rings are not expected to last long and are expected to disappear completely within around 100 million years.
On July 1, 2004, the Cassini−Huygens probe entered into orbit around Saturn. Before then, it flew close to Phoebe, taking very high resolution photos of its surface and collecting data. On December 25, 2004, the Huygens probe separated from the Cassini probe before moving down towards Titan's surface and landed there. It landed on a dry surface, but it found that large bodies of liquid exist on the moon. The Cassini probe continued to collect data from Titan and a number of the icy moons. It found evidence that the moon Enceladus had water erupting from its geysers. Cassini also proved, in July 2006, that Titan had hydrocarbon lakes, located near its north pole. In March 2007, it discovered a large hydrocarbon lake the size of the Caspian Sea near its north pole. The probe finally dived into Saturn's surface in September 2017.
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