Smog-covered Titan, Saturn’s largest moon, may be the result of a dramatic merger of two other moons that caused a variety of effects, including the formation of Saturn’s beautiful rings.
time Cassini – Huygens When the mission arrived in the Saturn system in 2004, it was greeted by a herd of animals. mysterious moon It has strange properties. titanthe second largest satellite in the world. solar systemIt is also the only moon in our cosmic neighborhood with an atmosphere reminiscent of organic molecules. And Hyperion has a battered and bruised body that looks like a giant pumice stone rolling around. Saturn. Meanwhile, Iapetus’ Yin-Yang world, with its two-tone hemispheres, is thought to have arisen as a result of its passage through Saturn’s E ring. The E ring is formed by material expelled from Saturn. EnceladusGeyser — has the most oblique orbit of Saturn’s major moons, forming an angle of 15.5 degrees with Saturn’s equatorial plane.
Astronomers led by Matija Chukwu of the SETI Institute now suspect that the creation of Titan as we know it today, through the collision and merging of two moons, triggered a chain of events that led to all of Saturn’s other features that we see today.
All these clues came from Cassini’s measurements of Saturn’s “moment of inertia.” This moment of inertia is governed by the mass distribution within Saturn itself. This moment of inertia is what controls how much Saturn’s axis of rotation wobbles like a top, a phenomenon known as precession. The period of Saturn’s precession was thought to match that of Earth in the distant past. Neptunealong its orbit, causing a gravitational resonance and began to pull Saturn at an angle of 26.7 degrees to the orbital plane around Saturn. solar. This tilt has the added benefit of allowing you to see Saturn’s rings more clearly. earth.
However, Cassini’s measurements of its internal mass distribution show that Saturn’s mass is slightly more concentrated in the center than previously thought. This therefore changes Saturn’s moment of inertia, making it slightly out of resonance with Saturn’s orbit.
Apparently, something brought Saturn and Neptune out of sync, resulting in a redistribution of mass within Saturn. But what on earth did that?
Despite having much less mass than Saturn, the ringed planet’s moons can have a surprisingly large impact on Earth. Originally, to explain why Saturn was no longer in resonance with Neptune, scientists came up with the theory that Saturn once had another icy moon, which they named Chrysalis. Researchers said the moon’s orbit may have been disrupted by a close encounter with Titan about 100 million years ago, bringing it too close to Saturn and being torn apart by tidal gravity. Most of the debris fell on Saturn, but some remained in orbit, forming rings. The interaction with Chrysalis, on the other hand, would have triggered an expansion of Titan’s orbit, which would have brought Saturn out of sync with Neptune.
This was a great theory, but when Chukku’s team tested it in simulations, they found that in most cases, Chrysalis would collide with Titan instead. But rather than the Chrysalis hypothesis being a dead end, the simulation opened another door, the key to which was Hyperion, another of Saturn’s moons that orbits just outside Titan.
Titan and Hyperion are another example of gravitational resonance. Their orbits are locked together, and for every four times Titan orbits Saturn, Hyperion completes exactly three revolutions, spinning chaotically around the ringed planet.
“Hyperion, the smallest of Saturn’s major moons, has provided us with the most important clues about the history of the Saturn system,” Chuk said in the paper. statement. “In simulations where the Extramoon became unstable, Hyperion was often lost and only rarely survived. We realized that the Titan-Hyperion lock was relatively new, only a few hundred million years old. This is roughly the same time that the Extramoon disappeared. Hyperion probably did not survive this upheaval, and if the Extramoon merged with Titan, it would create debris near Titan’s orbit.
Professor Cheuk suggests that Chrysalis is real and may have actually collided and merged with proto-Titan 100 to 200 million years ago, and that it was this collision that shaped much of what we see in the Saturn system.
For example, before the collision, Titan may have resembled Jupiter’s icy, airless moon Callisto, with an old, battered surface. The impact would have wiped Titan’s entire surface clean, which would explain why Titan has so few craters beneath its thick atmosphere. That atmosphere would have escaped from Titan’s interior during the collision. This collision caused Titan to fall into orbit around Saturn, widening its orbit and making it longer. It is now starting to gradually grow in a circular shape again.
Further simulations by scientists at the University of Edinburgh and NASA Ames Research Center suggest that changes in Titan’s orbit could have caused its tidal forces to wreak havoc on the inner medium-sized moons, even causing them to collide. Although most of the moons were re-formed from debris, some of the ice particles may have settled around Saturn, forming Saturn’s ring system.
The simulations also show that Chrysalis may have perturbed Iapetus’ orbit, leading to its high inclination.
It’s a nice and neat hypothesis, but that’s it for now. Although this idea is consistent with the facts, there is still no direct evidence. NASA’s Dragonfly mission to Titan, scheduled to launch in 2028, may find the first such evidence as it searches for further signs of Titan’s young surface, which indicates cataclysmic changes after the collision with Chrysalis more than 100 million years ago.
The findings from Ćuk’s team have been accepted for publication in Planetary Science Journal. preprint Available in the arXiv paper repository.