Albert McKeon

Aug 31st 2022

Saturn’s Rings Are Disappearing


Other than Earth, Saturn might be the most easily recognizable planet in our solar system. Its rings have mesmerized since Galileo observed them more than 400 years ago. Whether through a high-powered telescope or a small photograph, Saturn offers a striking reminder of how nature works in different ways. No other planet we know displays such prominent rings.

But what nature gives it can also take away. Saturn’s rings are disappearing. This won’t happen in our lifetime – scientists estimate the rings could vanish in fewer than 100 million years. The particles that make up the icy rings are losing a battle with the sun’s radiation and the gravity of Saturn. Even though we won’t be here to see the full demise of the rings, the thought of losing a landmark visual that makes the vast unknowns of space seem somewhat familiar is difficult to accept.

From Galileo to Cassini: Saturn’s Rings Are Revealed

On its own, Saturn would make an impression. It’s the second-largest planet in the solar system, after Jupiter. That size makes it the farthest planet from Earth that can still be seen with the naked eye. To get a true sense of its enormity, consider some big, colorful facts offered by Saturn’s volume is greater than that of 760 Earths combined, and it’s 95 times the size of Earth’s mass. The uniform bands of yellow and gold that give the planet a distinguished appearance are products of forceful upper-atmosphere winds (reaching as fast as 1,100 MPH) that combine with the heat of Saturn’s interior.

But clearly it’s Saturn’s rings that have most impressed many long-distance observers on Earth, a list that starts with Galileo. He first saw the rings through a telescope in 1610, but as the European Space Agency recounts, the famed Italian astronomer wasn’t sure what they were. Galileo thought they could have been ears because they were on each side of the planet. It took a stronger telescope for Dutch astronomer Christaan Huygens to theorize in 1655 that Saturn was surrounded by a solid ring.

Superior telescopes allowed scientists to see that Saturn has seven distinctive rings, which collectively stretch across thousands of miles and vary in matter and vibrancy. Many of them are comprised of billions of ice and rock particles that can be as small as a grain of sugar or as large as a house. The seven rings were each assigned a letter of our alphabet for identification, but the space probe Cassini has since revealed a more elaborate system of large and small rings that number more than 30.

The particles could be debris left over from comets, asteroids or moons that shattered from the force of the planet’s gravitational pull, according to LiveScience. But most astronomers aren’t entirely sure how or even when the rings formed, leading to polite arguments among scientists. One such back-and-forth centers on whether the dust of space that collects on the rings could actually confirm their age, as Quanta notes. This debate stemmed from scientists proposing in 2019 that the rings are probably 10 million to 100 million years old and not, as first believed, as old as the Solar System.

But the rings offer more than the wonders of sight. They also deliver answers through sound. One of the many discoveries recorded by Cassini is that the “C” ring of Saturn plays music of sorts. Convulsions in the planet’s gravity field make particles “prance” in the manner of waves, which can then be recorded like notes on sheet music and reveal characteristics of Saturn’s inner core, according to the New York Times. Those and many other discoveries, however, now seem somewhat fleeting after a recent estimate accelerated the end date of Saturn’s rings.

Will Saturn Lose Its Rings?

Unfortunately, not only does it seem certain that Saturn’s rings are disappearing, but it might happen sooner than we once anticipated.

The space probes Voyager 1 and 2 separately circled Saturn in the early 1980s and discovered what astronomers call “ring rain.” The planet’s magnetic field is pulling down the icy particles of the rings, dumping enough “rain” of watery elements into Saturn’s upper atmosphere to fill an Olympic-sized pool every half-hour, according to NASA. If this continues at the projected rate, eventually the voluminous materials that make up the rings won’t be so ample.

“Those particles are slowly jostling and bumping into each other,” Linda Spilker, a planetary scientist at NASA’s Jet Propulsion Laboratory, recently told The Atlantic. “There’s wakes created by tiny moons.”

As Spilker notes, when Cassini flew between Saturn and its rings, NASA was able to accurately measure the amount of ring material flowing into the planet, more so than it initially could from Voyager’s observations. Whereas Voyager led astronomers to believe the rings could survive for about 300 million years, enhanced transmissions from Cassini’s closer look at Saturn took roughly 200 million years off the rings’ shelf life.

That estimate could change. Saturn has a 29.4-year orbit that varies the rings’ exposure to the sun and alters how ultraviolet light makes them respond to the planet’s magnetic field. These variations could alter the quantity of ring rain and possibly hasten or slow the demise of the rings.

There is a bright side to the push and pull of Saturn’s gravitational field. As Spilker told The Atlantic, the probable way that the rings formed suggests that new ones could emerge — albeit, probably at least 100 million years from now.

“Maybe through some process — another moon is broken apart, a comet comes in too close — and you start it all over again. Maybe this isn’t the last we’ll see of rings around Saturn.”

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