Saturn Spectacular

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A In 1610, the Italian astronomer Galileo pointed his simple telescope at Saturn and was amazed by what he saw: ‘The planet Saturn is not alone, but is composed of three objects that almost touch each other and never move apart.’ Even more surprising, the two large shapes on either side of the main planet disappeared when he looked again a few months later. A frustrated Galileo decided never to look at Saturn again. Today, with much better telescopes, we know Galileo was actually looking at the planet’s unique, thin rings. Seen from the side, they looked like companion planets. Saturn’s magnificent rings consist of trillions of pieces of ice, some as small as a piece of dust. These particles are so small that they should scatter and fall into the planet, yet they stay in place. Scientists are still unsure about how the rings formed, their exact chemical makeup, and why they behave this way. B As amazing as Saturn’s rings are, its giant moon, Titan, is even more interesting. Although it is larger than the planet Mercury, Titan is basically a rock covered with ice and dirt. However, it has something no other moon has: a thick atmosphere with a pressure 50% greater than Earth’s. More interestingly, Titan’s atmosphere is mostly nitrogen (the main gas in our air) mixed with carbon compounds. Hidden under this atmosphere, Titan’s surface might be similar to the early Earth, but astronomers cannot see through the moon’s thick orange fog. C Many Earth-like chemical reactions could happen on Titan. Scientists are careful when talking about life on Titan, but it is a small possibility. Living there would be very difficult. Because Saturn is so far away, the sun looks very dim, making Titan an extremely cold place. Surface temperatures average about –300 degrees Fahrenheit, so liquid water cannot exist on the surface. Also, there is no oxygen in Titan’s air. The only slim hope for life is if water mixed with ammonia gets warm enough deep underground to turn into liquid. If so, simple life forms could survive there, similar to the strong microbes living near deep, hot cracks in Earth’s oceans. D Titan could hold clues about the early chemistry that created life on Earth. The freezing temperatures that make Titan so harsh for life actually make it very useful for science. Titan’s cold climate preserves chemicals, meaning it has kept most of the substances it gathered over 4.5 billion years. The early chemical reactions that started life on Earth are gone, erased by our planet's fast geological changes. On Titan, similar reactions are perfectly preserved in the cold. E Compared to its rings and its mysterious moon, Saturn itself might seem quite ordinary. Yet, the 75,000-mile-wide planet—the second largest in the Solar System—is fascinating. Like Jupiter, Saturn is a gas giant: a small rocky center surrounded by huge amounts of helium and hydrogen. Saturn is very light; it is even less dense than water. It releases heat, but scientists are not sure why it produces any heat at all. Surprisingly, Saturn’s storms are stronger and faster than Jupiter’s. However, the planet looks plainer because a thick cloud of ammonia hides the colorful stripes that we can easily see on Jupiter. F Scientists hope that studying Saturn will explain how giant planets form and how different weather systems work. A recent spacecraft, the Cassini-Huygens probe, has sent back results that Galileo would have loved: photographs showing Saturn perfectly clearly. After scientists finish studying all the data from this mission—which might take 40 years—many of these mysteries may finally be solved.