Scientists have traced the long chain of events that caused Saturn's axis of rotation to tilt unusually, eventually leading to the planet's grandiose ring system.
Saturn boasts the largest and most beautiful ring system in the entire solar system. Their origin and age are still not exactly known. According to one hypothesis, the rings are several billion years old like the planets near the Sun and originated from the same protoplanetary cloud. Others believe that Saturn's rings are the remnants of a satellite that was already destroyed when the dinosaur age was at its height on Earth. However, most of the data points to the second option. It confirmed a new work of astrophysicists from the Massachusetts Institute of Technology (MIT), whose article was published in Science magazine.
The work of Jack Wisdom and his colleagues began with another unusual feature of Saturn. This planet's axis of rotation is markedly - by 27° - deviated from the perpendicular to the plane of its orbit. The fact is that the planets are formed from a gas-dust cloud that orbits a young star and retain the basic parameters of this cloud's motion. A deflection of the axis of rotation, like that of the Earth, is almost always the result of collisions. However, there is no known body massive enough to turn the huge Saturn or any of its remains.
It is therefore assumed that Saturn's tilt is caused by a unique connection with neighbouring Neptune. Saturn's axis precesses, tilting slightly sideways, and these oscillations coincide with the precession of Neptune's orbit. They are accentuated by the slow migration of Titan, Saturn's largest moon, which is gradually drifting away from Saturn at about 11 cm a year. The work of Jack Wisdom and his colleagues drew on these hypotheses. The scientists used measurements of Saturn's gravitational field made by the Cassini probe. But when they refined the planet's rotation parameters, they found that the precession of its axis was no longer 'in sync' with Neptune so precisely, as if thrown out of balance by some extraneous influence.
Astronomers ran a number of simulations, trying out different scenarios involving the migrations of Saturn's major moons. The picture only emerged when one more was added to the planet's known satellites. The simulation showed that the hypothetical object (the authors called it Chrysalis, Chrysalis) could be between the orbits of Titan and Japetus, the third largest of Saturn's moons, and gain about the same mass as Japetus. About 100-200 million years ago, a chaotic gravity play between multiple moons threw it out of orbit. This put Saturn out of resonance with Neptune and caused Titan to migrate away.
Scientists simulated these events 390 times, yielding different possible scenarios. In some, Chrysalis collided with Titan or Japetus, while in others it was ejected away from the Saturn system. But in some cases the satellite quickly fell to the planet and was torn apart by tidal forces in its powerful gravitational field, and the remains turned into rings. Unfortunately, in this beautiful and logical sequence of events, one thing embarrasses: Astronomers obtained such a result only in 17 simulation cycles out of 390. Whether the real events went according to one of these variants can only be guessed so far.