Saturn's Rings Just Got a Death Date

NASA's Voyager spacecrafts recorded data suggesting Saturn's rings were disappearing when they whipped past the planet decades ago. Now, confirmation: The rings have likely existed for only a fraction of the planet's 4.5 billion years and will be gone in an astrological flash, reads a new NASA study appearing to confirm a theory raised with the Voyager missions in the 1980s. Essentially, ultraviolet light from the sun and plasma clouds from tiny meteoroid strikes electrically charge the ice particles that make up Saturn's rings. Once bound to the planet's magnetic field, which curves into the northern and southern hemispheres, the particles are pulled into the planet and vaporized. And fast: NASA scientist James O'Donoghue says the process known as "ring rain" drains enough water from the rings to "fill an Olympic-sized swimming pool ... in half an hour."

Saturn's rings would disappear in 300 million years at that rate, though scientists expect some variation over the course of Saturn's 29.4-year orbit, per CNET. Before NASA's Cassini spacecraft was crashed into the planet last year, however, it detected water ice also falling into Saturn's atmosphere at the equator. Combining this finding with the current rate of ring rain, O'Donoghue argues Saturn's rings "have less than 100 million years to live." That's about as long as the rings have probably existed, the scientist says, meaning Saturn has spent roughly 98% of its life without the rings. "We are lucky to be around to see Saturn's ring system," adds O'Donoghue, though he notes "perhaps we just missed out on seeing giant ring systems of Jupiter, Uranus, and Neptune, which have only thin ringlets today." (Cassini gave us our closest look yet at Saturn.)