Saturn’s rings are disappearing, and we don’t know how long they will remain.
Astronomers have known this since the 1980s SaturnThe inner ice rings are steadily eroding in the upper atmosphere. Heavy rainfall occurs at a rate as high as an Olympic pool of water It’s raining On the gas giant daily. However, how fast is the Iconic ring system It shrinks—what determines when it will go away—remains an open question.
Fortunately, the mighty NASA James Webb Space Telescope (JWST or Webb), whose powerful instruments hitherto fired the most distant galaxies from the early universe, will soon investigate this intriguing phenomenon found much closer to home.
“We’re still trying to figure out exactly how fast they’re eroding,” said James O’Donoghue, a planetary scientist with the Japan Aerospace Exploration Agency who will lead the new effort to determine how long Saturn’s rings will last. statement (Opens in a new tab) Posted on Monday (April 17). “Currently, research indicates that the rings will only be part of Saturn for another few hundred million years.”
Related: Saturn: everything you need to know about the sixth planet from the sun
To better estimate the age of Saturn’s iconic rings, JWST and the Keck Observatory in Hawaii will be part of a long-term observational campaign to study the planet. Telescopes will help monitor how “ring rain” fluctuates during one full season on the gas giant, which lasts about seven Earth years thanks to its orbit away from the sun.
Astronomers expect interesting data from the campaign, as previous research has shown that huge amounts of ring material are constantly falling on Saturn. For example, data sent home from NASA Cassini The spacecraft — which floated directly across the gap between Saturn and its rings 22 times as it plunged into the planet in 2017 — revealed that between 880 pounds (400 kg) and 6,000 pounds (2,800 kg) of icy rain is pouring down on Earth. planet every second and heating of the upper atmosphere.
At this rate, the episodes might be vanished In about 300 million years. Although this may seem far away, the flood leads the symbolic ring system to “Relatively quick deathOn cosmic time scales. But the rate of precipitation of ringed matter on the planet remains highly uncertain; the rings could disappear as quickly as 100 million years, or they could remain suspended for 1.1 billion years, the astronomers say.
“Right now we only have one estimate that’s very broad,” O’Donoghue told Space.com on Wednesday (April 26). “We want to make more observations that narrow down this flow.”
According to current research, space and sun rocks radiation The ring particles slightly distort and give it an electric charge so that it binds to the gas giant’s magnetic field lines. Saturn’s gravity then pulls the icy particles inward, which are directed by magnetic fields to flow into the planet’s upper atmosphere, though not always at the same pace.
As Saturn orbits the Sun in its 29.5-year orbit, it turns toward and away from the Sun, and its rings do the same. Astronomers say this tilt determines how much the sun’s radiation affects the inner layers of the ring system — where much of the icy rain is triggered — and may also play a role in determining how much material falls on Saturn.
“We suspect that when the rings are at the edge of the sun, the ring rain will slow down,” O’Donoghue told Space.com. “And as they tilt to face the sun, the circular rain flow will increase.”
So his team will use the Webb and Hawaiian Cake Observatories to measure emissions from a specific hydrogen molecule in Saturn’s upper atmosphere. Measurements of this molecule rise when a small amount of material falls from Saturn’s icy rings into its atmosphere, but dwindle during heavy rain, O’Donoghue told Space.com. Observing these shifts in these hydrogen emissions during one full season on Saturn could help the team determine how much ring material should rain on the planet.
“The tool on Keck that we used for this before has been upgraded, and we’ve never used JWST for this before,” he said. “So we’ll be able to appreciate the flow of episodes better than ever before.”
While the new research will help predict the fate of the rings, astronomers who study the world of Saturn continue the decades-old debate about how and when the planet’s rings were born in the first place. Various models have shown that the rings were a permanent structure around Saturn 4.5 billion years ago — when the solar system itself was forming, but data from the Cassini spacecraft painted a much younger picture, aging them by only 10 to 100 million years. old.
The discrepancy arose because older rings are often darker, but Cassini captured Saturn’s rings to be bright, indicating their youth. In 2019, astronomers who Reconsider the discussion (Opens in a new tab) He suggested that heavy circular rain might be responsible for the rings appearing at such a young age, going back to the original idea that the rings are as old as the solar system after all.
“I think it would be pretty cool if the rings were only 100 million years old or so and that they were billions of years old,” O’Donoghue told Space.com. “Because it means we evolved in time to see them before they were gone.”
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