What Is Saturn's Age?
Saturn, the second-largest planet and the sixth planet from the sun, is made mostly of gas, primarily hydrogen and helium. It has seven rings, each containing many ringlets made of ice particles and rocks. Saturn is the same age as the sun and the other planets in the solar system, about 4.6 billion years old. Scientists used to think Saturn's rings are younger than the planet itself, but now they think the rings and the planet are the same age.
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Age of the Solar System
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Scientists calculated the age of the solar system by studying meteorites, which are thought to be as old as the system itself. They used radioactive dating to determine the age of the meteorites and concluded that the solar system--the sun and all of the planets, including Saturn--is about 4.6 billion years old.
Dating Meteorites
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Scientists tested thousands of meteorites. They measured how much the composition of lead in the meteorites changed over time because of the decay of radioactive uranium. Using this data, researchers were able to date the solar system with an uncertainty level of less than 1 percent.
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Earlier Theory of the Age of Saturn's Rings
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Scientists used to think Saturn's rings are much younger than the planet. Data from the Voyager spacecraft in the 1970s and from the Hubble Space Telescope suggested the rings might have formed when a comet hit a moon, perhaps as recently as 100 million years ago.
Current Theory of the Age of Saturn's Rings
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Starting in 2004, data from the spacecraft Cassini indicated that Saturn's rings are much older than scientists had thought. In fact, the data suggested that there were always rings around Saturn and that they will continue to be there for billions of years more. Scientists think the material in the rings is constantly changing.
Hypotheses About the Origin of the Rings
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Researchers have two hypotheses about the origin of the rings. One is that the rings were formed of debris left over from Saturn's formation. The other is that the rings were formed from pieces of moons that had broken apart over time.
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- Photo Credit NASA/JPL/Space Science Institute
