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The young, ephemeral rings of Saturn

Simulation of how Saturn's rings could disappear over the next 300 million years


First observed in the seventeenth century by Italian astronomer Galileo Galilei, Saturn’s rings are its most iconic and intriguing feature. Two recent studies have presented new theories on their origin and probable end. One suggests that the rings of ice and dust surrounding Saturn are much younger than the planet itself. Data collected by the Cassini space probe in 2017, before it plunged to its demise in the planet’s atmosphere, allowed scientists to calculate the mass of the rings with unprecedented accuracy. Based on this data, researchers in Italy, Israel, and the USA estimated that the rings are somewhere between 10 and 100 million years old, making them much younger than Saturn, which formed 4.5 billion years ago (Science, January 17). In another study, researchers in the UK and the USA estimated how long the rings may last. From the Keck Observatory in Hawaii, they measured the temperature and density of Saturn’s atmosphere, which is rich in hydrogen. The only explanation they could offer for their findings was that ice particles from the rings were entering the atmosphere. Attracted by gravity and the planet’s magnetic field, they are falling into the planet at the maximum rate estimated by the Voyager probes in the 1980s. According to the researchers’ calculations, a volume equivalent to one Olympic swimming pool reaches the planet every half an hour (Icarus, December 17, 2018). They estimate that at this rate, the rings will disappear in about 300 million years.