The big moon is ‘knocking down’ the ringed planet, and that may destabilize its trajectory in the future

Titan, Saturn’s largest moon and one of the most promising places to find life in the Solar System, could end up crashing into the great ringed planet. But it could also be ‘expelled’ from our planetary system and lost forever in the vast solitude of outer space.

Its final destination depends, to a large extent, on how the enormous influence that this moon has on the tilt of the planet evolves, and on whether its slow but continuous outward migration is capable, one day, of ‘knocking down’ Saturn itself.

Titan, in fact, is moving away from Saturn at a speed of about 11 centimeters per year. It is not a rare phenomenon: our moon, without going any further, is also moving away from the Earth, at a rate of just under 4 centimeters per year. The point is, Titan’s ‘escape’ is happening much faster. As the orbit of Titan moves away from Saturn, it affects the rotation of the planet, causing it to oscillate more rapidly on its axis. And that ‘wobble’ has a direct consequence: slowly, but inexorably, Saturn is tilting.

If Titan continues to migrate as predicted from this observed rate, says Melaine Saillenfest, from the French National Center for Scientific Research and first author of a paper just published in arXiv, then the tilt of Saturn’s axis will probably increase in the next few billions of years.

Together with Giacomo Lari, from the University of Pisa, Salleinfest has carried out a series of simulations of this process. And they have discovered that Saturn could be tilted up to 90 degrees, which means that the direction of its rotation would be perpendicular to the plane in which the Sun orbits. A similar mechanism could explain why Uranus is tilted 98 degrees, a characteristic that Astronomers attributed largely to major collisions in the planet’s past. However, that explanation is still up for debate, and this alternative mechanism could be a solution.

Titan, adrift

But the tilt of Saturn is not the only effect that the migration of Titan will have. Quite the contrary, the action of this moon could end up turning against itself. If its orbit continues to widen, it will indeed reach a critical point where various gravitational forces will destabilize its trajectory. The researchers found that this will happen when Titan is twice as far from Saturn as it is now. At that point, according to the simulations, Titan is likely to be ejected away from Saturn, or instead end up falling directly toward the planet.

The destabilization of Titan, according to Saillenfest, would also have important consequences for the entire Saturn satellite system, possibly with more ejections or collisions between moons.

However, the very fact that this process takes billions of years to complete means that it may never actually happen. In fact, if it takes long enough, the Sun will turn into a red giant much sooner, devouring the inner planets and catastrophically reshaping the entire Solar System.

Image Credit: Getty

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