Saturn’s rings capture our imagination like few other natural phenomena can, yet its beauty could soon fade away faster than we anticipated.
Cassini spacecraft, which orbited Saturn from 2004 to 2017, recently released data suggesting its rings are losing tons of mass each second – suggesting they may disappear before our grandchildren even take to their grandchildren’s shoes!
What’s Happening?
Astronomers first observed “ring rain” back in the 1980s. At that time, astronomers estimated the iconic rings had approximately 300 million years left before they’d dissipate entirely; but Cassini has since shown this process moving much more rapidly than anticipated – recent research published in Icarus suggests this process dumping 10,000 kilograms per second of icy particles into Saturn’s atmosphere, or equivalent of two Olympic-sized swimming pools being filled every hour!
To gauge how fast ring material was raining down, researchers employed data from Cassini probes that sailed directly through Saturn’s rings and through Encke Gap, in addition to considering Saturn’s orbit (which takes 29.5 years) – all factors which affect how quickly material is pulled into Saturn and lost.
As soon as ring particles enter Saturn’s atmosphere, they lose their magnetic force and begin drifting randomly in all directions. Their speed of migration depends on several factors such as Saturn’s orbital tilt; its largest moons (Titan and Enceladus) may also play a part in shaping their fates.
As the rings move through space, their particles collect dust and other debris from their surroundings – this makes the rings appear younger than they actually are – yet if somehow we could prevent the rings from colliding with Saturn they’d brighten back up again and give us another opportunity to witness all their glory.
Saturn’s rings are composed of almost entirely frozen water with only trace amounts of rock material present; even though they appear so huge, they only account for 40% of Mimas, one of Saturn’s smaller moons.
The Rings Are Raining Down
Astronomers have known since the 1980s that Saturn’s iconic rings have been steadily deteriorating at an alarming rate, losing an estimated 22,000 pounds per second, equivalent to filling an Olympic-sized swimming pool. Meteoroids passing through these rings and redistributing material pushed inward toward Saturn are likely contributing significantly. Recent research published in Icarus suggests they don’t have much time left, according to new studies conducted on their future erodability.
As Saturn’s icy rings erode, they produce dust clouds which release energy that heats its atmosphere, an extremely well-known phenomenon. However, the details surrounding this process were still unclear until now. To better understand it, researchers analyzed data collected by NASA’s Cassini spacecraft over 13 years and 22 orbits from Saturn’s inner rings where particles fell as part of this ring system onto planet Saturn itself.
Monitoring the temperatures of incoming particles allowed the team to identify what was heating up the atmosphere. They discovered that raindrops contain hydrogen, water and complex organic molecules such as butane and propane; although hydrogen was expected, carbon wasn’t typically part of its composition – an unexpected discovery!
The team also conducted measurements to establish how fast the rings are receding; currently they appear to be losing several tons of mass every second – similar to Voyager 1 and 2 estimates – suggesting they may only remain around for another 100 million years or so.
As Uranus and Jupiter show us, massive planetary rings don’t last very long; Saturn may soon follow suit and become part of history as its rings become fashion statements that eventually get ripped off to collect dust in a closet. Luckily, when James Webb Space Telescope (JWST) launches in 2021 it should provide insights into these rings as to their origin and future development.
The Rate Is Accelerating
Since 1975, when Voyager 1 and 2 first flew by Saturn and captured stunning images of its atmosphere, moons, and iconic rings – including evidence that they are gradually dissolving at an alarming rate, likely leading to their demise within 100 million years – nearly four decades have passed since these landmark missions made their historic visit.
Voyager probes first detected evidence of this “ring rain” through various phenomena: changes to Saturn’s electrically charged ionosphere, density variations in its rings and narrow dark bands encircling Saturn at mid-northern latitudes. This phenomenon results from an ongoing tug-of-war between gravity (pulling particles back toward Saturn) and orbital velocity (flinging them away into space).
Ring rain consists of dusty chunks of ice that are being drawn down towards Saturn far faster than scientists originally imagined. As they head toward its surface, these particles spiral downward along invisible magnetic field lines and dump water at specific latitudes into Saturn’s upper atmosphere – dissolving away haze that gives its rings their dark look in reflected light, creating narrow bands as captured by Voyagers.
These icy particles are dissolving into gaseous form as they react chemically with Earth’s ionosphere, producing electrically charged hydrogen atoms called H3+ ions that glow brightly under infrared light. By measuring how many H3+ ions were produced during this process, researchers could gauge how much rain was being lost through this method.
Combine this data with what Cassini had detected of ring material, they were able to accurately calculate how fast the rain of ring rain was dissipating; their calculations found it was about 100 times faster than they’d initially predicted for Voyagers.
Research by NASA scientists has provided answers to an age-old mystery about when and how Saturn’s rings first appeared, suggesting they likely originated with Saturn rather than being added on later. Their discovery built upon earlier findings suggesting they may be ancient; perhaps formed through collisions between one of Saturn’s moons and a comet before even Solar System was formed! Indeed, similar collisions may still be taking place resulting in gaps appearing among Saturn’s rings over time.
The Rings Could Disappear in 100 Million Years
The rings of Saturn are one of the Solar System’s most recognizable landmarks, easily seen with any pair of binoculars or backyard telescope. We often take their visibility for granted; however, astronomers have discovered that their lifespan has come to an abrupt halt, dissolving at an alarming rate.
The shimmer of Saturn’s rings comes from billions of tiny particles made primarily of water ice that scatter sunlight and reflect it back, but these particles don’t stay still; they are continuously being bombarded by ultraviolet radiation from the Sun as well as plasma clouds from meteoroid strikes, which ionize these particles and strip off electrons which are funneled toward high northern and southern latitudes of Saturn where they fall like raindrops – this process is known as “ring rain.”
Scientists published in Icarus this month used dust counts from Cassini’s Cosmic Dust Analyzer (CDA) data to calculate how long particles had been gathering on Saturn’s rings and estimated how quickly these rings might disintegrate under current rates; with half-hourly dust-icefall estimates taken into account, their conclusion was that, at current rates, Saturn will absorb its rings within 100 million years or less.
Researchers want to test this prediction by employing NASA’s James Webb Space Telescope and Hawaii’s Keck Observatory as long-term instruments of observation of Saturn’s ring rain phenomenon at both wavelengths. Their observations will cover an entire season on Saturn which lasts roughly seven Earth years.
These findings will add fuel to the debate surrounding how and when Saturn’s rings formed. Astronomers had long assumed they were permanent features present since Saturn first took shape; but research now indicates they may have formed later as accessories.
Research supports the theory that Saturn’s rings originated when two icy moons collided and shrunk apart into pieces that fell into its orbit, eventually coming together and forming brightly-ringed planet.