Area Grime Reveals Age of Saturn’s Rings
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• Physics 16, 83
Micrometeoroids in Saturn’s rings reveal that these dusty bands are not more than 400 million years outdated, making them considerably youthful than the 4.5-billion-year-old gasoline big.
NASA; JPL-Caltech; Area Science Institute
With its vast bands of encircling mud, Saturn’s rings are the most important and brightest in our Photo voltaic System. They’re additionally essentially the most mysterious. Unanswered questions stay about why, how, and when the seven rings shaped. Now Sascha Kempf of the College of Colorado Boulder and colleagues have addressed the latter downside, utilizing mud contaminants inside the rings to position an higher restrict of 400 million years on the rings’ age [1]. Kempf says that for so long as he’s been within the discipline, astronomers have been discussing whether or not Saturn’s rings are as outdated because the planet or if they’re youthful. Now they know. “They’re considerably youthful,” he says.
Kempf and colleagues produced their age estimate by finding out the contamination fee of the rings by small items of rock and particles, generally known as micrometeoroids. These contaminants are always zooming round our Photo voltaic System, colliding with objects of their paths. When one in all these micrometeoroids hits one in all Saturn’s rings it will possibly get integrated into the ice the rings include. Kempf and colleagues realized they may use the speed at which this course of occurs as a clock to disclose the rings’ age.
A lot of the contamination of Saturn’s rings comes from Saturn’s moon Enceladus, which has geysers that shoot out ice and water. This contamination accommodates little or no rocky, carbon-based materials, says Andrew Poppe, an area scientist on the College of California, Berkeley, who was not concerned within the new examine. As such, the darkish pollution inside Saturn’s rings predominantly come from past the Saturnian system. As well as, Poppe notes that the air pollution from Enceladus strikes very slowly, whereas mud originating from exterior of the Saturnian system strikes a lot quicker. Interstellar mud additionally spirals inward towards the planet’s floor. It was these interplanetary explorers that the researchers looked for of their examine.
Kempf and his group used the Cosmic Mud Analyzer aboard the Cassini spacecraft for his or her flux measurements. From 2004 to 2017, when Cassini was deliberately destroyed by being plunged into Saturn’s ambiance, this instrument collected over 2 million grains of mud and rock from round Saturn, recording every grain’s velocity. The group used this velocity info to find out the probably origin of every grain, filtering out people who got here from Enceladus to go away solely the interplanetary ones. Of the two million particles collected, this filtering left round 160, Kempf says. “It [was] a needle within the haystack downside.”
These 160 particles point out an interplanetary mud contamination fee of lower than a gram of mud per sq. foot of ring per yr. Utilizing this fee and the worth of the overall contamination of the rings, which measurements present lies between 0.1% and a couple of%, the researchers positioned the age of the rings between 100 million and 400 million years outdated. “Saturn’s rings are extremely clear,” which signifies that they’re much youthful than the planet they encompass, Kempf says.
Now that scientists have clear bounds on the rings’ age, theorists might want to develop fashions that may clarify how Saturn’s rings shaped on such a brief timescale, says Sean Hsu, a analysis affiliate on the College of Colorado Boulder. He was not concerned within the examine. “I believe this [result] will actually excite modelers.” Hsu says that many scientists assumed that the Photo voltaic System as we see it right now was set in place billions of years in the past. The brand new outcomes seem to negate that assumption, as they point out that a few of the Photo voltaic System’s buildings shaped comparatively just lately in planetary historical past. Different outcomes present that these buildings would possibly nonetheless be in flux. For instance, beforehand launched information indicated that particles inside Saturn’s rings are being pulled by gravity out of the rings, towards the planet, making a dust-ice rain. That course of is so fast that Saturn’s rings are anticipated to vanish inside 100 million years. Given their brief and dynamic life, we received “fortunate” to see Saturn’s “magnificent” rings as we do now, Hsu says.
–Allison Gasparini
Allison Gasparini is a contract science author based mostly in Santa Cruz, CA.
References
- S. Kempf et al., “Micrometeoroid infall onto Saturn’s rings constrains their age to no quite a lot of hundred million years,” Sci. Adv. 9 (2023).
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