The Idiot’s Guide to Everything: Saturn

Posted on November 30, 2011

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SATURN

The outer solar system is full of some of the most aesthetically breathtaking worlds known. Of all however, one stands out and captivates people of all ages. It is probably the most popular planet amongst the general population, and it is synonymous with our knowledge of space. This, of course, is Saturn. If you ask a young child to draw a planet, the chances are they will draw something strikingly similar to Saturn, with its glorious rings surrounding it. It is the defining world in our solar system, the one that draws in the curious and captivates the experts. Despite its beautiful image however, Saturn is a violent world of raging storms and sub freezing temperatures, and its rings are made of masses of ice rocks hurtling around at breakneck speeds. It is a beautiful contradiction.

The 6th planet from the sun, Saturn is also the 2nd largest in our solar system, around 755 times the size of Earth. It is strikingly similar to Jupiter, in that it is made up mostly of hydrogen and helium, and has its own mini solar system of moons. It has a similar interior, with a small (by its own standards) rocky core at its centre. It has less distinctive surface patterns than Jupiter however, which gives it its cloudy appearance. It is also twice as far from the sun as Jupiter is, at an average of 890 million miles. Despite its huge size it has incredibly low density, so low that if there was an ocean big enough for it to fit in, it would float. It is the only planet that is less dense than water. A day on Saturn lasts 10 hours and 39 minutes, so not massively dissimilar to Jupiter, and a year lasts around 29.4 Earth years. Because of its low density and fast rotational speed, it is shaped like a flattened ball. It is a planet of storms, with wind speeds reaching up to 1,800km/h, which is far quicker than anything found on Jupiter. It has bands of storms like Jupiter, only much blander, and it also has great storms, but nothing on the scale of the Great Red Spot. It is unique however in that it has a warm south pole, where the average temperature is higher than anywhere else on the planet. The Cassini observational spacecraft has recently discovered a hurricane-like storm on this pole, that has a clearly defined storm eye. This is fascinating, because it was previously believed that only storms on Earth contained these eyes.

The existence of Saturn has been known by humans since pre-historic times. It is named after the Roman god of agriculture, and its Greek equivalent is Kronos. When making his observations of the planets in 1610, Galileo was the first to come across what we know today as the rings of Saturn. At the time however, Galileo believed them to be two moons, as his vision of Saturn was embellished by two circular objects either side. He famously said that it seemed that Saturn had ears, that maybe it had ‘swallowed his own children. The theory of Galileo was disproved in 1655 by Christian Huygens. Better known for creating the pendulum, Huygens was able to use a large telescope and refuted Galileo’s moons theory, stating instead that it was surrounded by rings. Huygens also discovered Saturn’s largest (the solar systems second largest) moon, the fantastically named Titan. In 1859, James Clerk Maxwell proposed that the rings must be composed of numerous small particles, which of course was proved correct. The planet was first visited by Pioneer 11 in 1979, and in 1980 Voyager 1 sent back the first high resolution images of Saturn. The real progress with regards to Saturn and our knowledge of it has been made by the Cassini-Huygens spacecraft, which first entered the orbit of Saturn in 2004. It has since sent back some spectacular surface radar images from Titan, showing its lakes and mountains. It also discovered the ice geysers that are found blasting out of the southern pole of another of Saturn’s moons, Enceladus. This has excited scientists, because the theory goes that where there is water, there is life.

Saturn has around 60 known moons. Titan is its largest and comprises 90% of the mass in orbit around Saturn. The majority of the moons are less than 50km in diameter however, and only a small number of the moons are worth discussion. As mentioned previously, there are theories that Enceladus may harbour life, due to its ice geysers at its southern pole. Another of Saturn’s moons, Rhea, is thought to have rings of its own. Much like Jupiter, Saturn’s moons create their own mini planetary system. I will write further about Titan at a later date, as it is one of the most fascinating worlds in all of the solar system.

When talking about Saturn however, the conversation almost inevitably always leads to one thing in particular, and for good reason. Its spectacular rings. All of the gas giants have rings of some sort around them, but it is the rings of Saturn that are most famous, the show stoppers of the universe. They are composed of countless boulders of various sizes, from specks of dust to metres. They are almost entirely water ice, and as a result are extremely bright, as the ice is reflective. The rings are very flat, averaging only 20 metres in thickness. According to scientists, ring systems should not last any longer than 100 million years, which leaves two theories as to the age of the rings. The first of these is of course that they are very young, only clumping together within the last 100 million years. The second and most widely held belief is that the ring system is constantly replenished by debris floating throughout space. The rings themselves are thought to be the remains of moons that have been stripped of their shells before crashing into Saturn itself. The rings have 7 major regions, and the largest of these (A-B-C) are readily visible from Earth, but only with aided vision. The A-B-C rings are the main ones, and are much denser than the rest. They contain the largest particles. The D-E-G rings are mere dust rings, containing far smaller particles. The F ring, which is found on the outer edge of the A ring, is a mixture of the two. A number of Saturn’s moons are also found within the ring structure, and scientists believe that these sometimes act almost like shepherds. Countless theories abound about the rings, mostly because they are the most glorious image in all of our solar system.

Is there life on Saturn? This is an easy question to answer, and that answer is no. However, some of Saturn’s moons are fascinating in this regard. As mentioned earlier, shooting ice geysers have been found on the poles of Enceladus, which led scientists to believe that liquid water could be very near the surface. Saturn’s largest moon, Titan, is another source of query for life searchers. The environment and atmosphere of Titan is similar to what early Earth may have been like, and there are theories that life could exist in the methane lakes of Titan. This will be looked at later on when discussing Titan in full. For Saturn however, there is no life, but there are violent storms, Earth-esque hurricanes and rings. Beautiful, beautiful rings.

 

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