A debate about the age of Saturn’s resplendent rings has been raging for a number of many years now, with no sign of ending. A new examine by researchers at the Institute of Science Tokyo and the Paris Institute of Planetary Physics has recent spin to supply now that would recast the dialog.
Saturn’s rings are an arresting sight even by way of modest telescopes. The planet is made principally of hydrogen and helium whereas the rings are billions of items of principally bright-white water ice and rock. Some of those items are as small as a grain of salt; others are as large as a home.
Four spacecraft have visited Saturn to date, all launched by NASA: Pioneer 11 and the twin Voyagers 1 and a pair of flew by it whereas Cassini orbited Saturn from 2004 to 2017.
Unusually clear
Cassini particularly discovered the rings to be squeaky clear, with little or no grime. This is uncommon as a result of every thing in the Solar System, together with the earth, is consistently bombarded by darkish items of mud, every finer than a grain of sand. These particles are fragments of bigger chunks of rock in house.
Most of this particles burns up in the earth’s environment when they get too shut and by no means attain the floor.
Around Saturn, astronomers anticipated this darkish mud to be omnipresent in the rings, however this isn’t the case.
Based on this, scientists hypothesised that Saturn’s rings are comparatively new, solely round 100 million years previous — too younger to have accrued the mud.
This was a easy clarification, which is sweet, however there’s a catch: scientists don’t know how the rings may have fashioned so just lately.
Rings out of time
In these final 100 million years, the Solar System has been fairly calm.
“In the very early stages of the formation of our solar system, around four billion years ago, the system was chaotic and unstable,” Ryuki Hyodo, from the Institute of Science Tokyo, Chief Science Officer at Tokyo-based firm SpaceData Inc., and a coauthor of the new examine, stated. “Therefore there is a greater chance of a big, dynamical event happening then that could form Saturn’s rings.”
“Crater size distribution is used to constrain the age of solid bodies in the solar system,” Sean Hsu, a analysis scientist at the University of Colorado Boulder who wasn’t concerned in the new examine, added. “For Saturn’s rings, age determination is even more difficult — there are no craters, and the collisional nature of ring particles erases most of its history. Depending on which measurements you choose, it is not too surprising that people end up with very different age estimates.”
“In my view, the ‘blind men and an elephant’ is not a bad metaphor here.”
Keep ‘em out
In the new analysis, Hyodo’s laptop fashions confirmed that when mud particles collided with ice in Saturn’s rings, they evaporated and dispersed into lots of of even smaller flecks, which Cassini had additionally noticed.
The fashions confirmed that these particles then smash into Saturn itself, beat the planet’s gravitational pull or are dragged into the planet’s raging environment. In different phrases, the pearly shine of Saturn’s rings shouldn’t be due to them being younger however as a result of they have a technique to eject such international our bodies that enter their delicate world. In sum, there’s no purpose for older rings to be darker (or vice versa).
In truth, the rings might be as previous as the Solar System, in keeping with Hyodo.
“The basic assumption in the debate about the age of the Saturnian rings centres around the water ice composition of the ring particles,” Wing-Huen Ip, who research the origins of the Solar System and the formation of planets at the National Central University, Taiwan, and who was not part of the new examine, stated. “We actually can’t be 100% sure that this is true.”
“Such an estimate is indeed questionable, because we do not know what the ring composition was when it formed,” Hsu stated.
The new findings have been printed in the journal Nature Geoscience in December 2024.
Europa, Enceladus, and past
Determining when Saturn obtained its signature rings isn’t only a matter of curiosity. “The interest in probing the age of Saturn’s rings is beyond the rings themselves — it is about the implications, and there are many,” Hsu stated. “Enceladus, the geologically active moon of Saturn, is a top-priority target to study habitability and astrobiology due to active plume activity from its subsurface ocean. The evolution of Saturn’s rings has fundamental impacts on the evolution of Enceladus, and other icy moons of Saturn, as they’re dynamically coupled.”
In the mid-2000s, Cassini discovered plumes considerable in water molecules leaking from Enceladus’s southern hemisphere. It additionally recorded proof of cryovolcanoes, icy promontories spewing hydrogen, salt crystals, water vapour and ice, and risky compounds like ammonia. The vapour condenses into strong flakes, not not like snow on the earth, and drifts into certainly one of Saturn’s rings.
In 2014, NASA scientists reported discovering proof of a 10-km-thick ocean of liquid water below Enceladus’s south pole area in Cassini information. Ip believes investigating how icy grains from the plumes of Enceladus have an effect on the ring’s composition may play a serious position in figuring out the ring’s age.
In associated information, NASA launched the Clipper mission to review Jupiter’s moon Europa, which is equally dynamically linked to Jupiter and comprises a subsurface ocean as properly, in October 2024.
The new examine may additionally assist clarify why the Solar System’s 4 fuel giants have such various ring techniques. Either they have been completely different by start or diverged as they grew. The dynamics unveiled in the examine may infuse recent perception into this debate.
“We may propose to send a spacecraft to Saturn’s rings to study them in more detail,” Hyodo stated.
Unnati Ashar is a contract science journalist.
Published – February 19, 2025 05:30 am IST
