Our own Moon moves a little further from Earth each year, and has been doing so since its formation, billions of years ago. When a moon orbits, its gravity ‘pulls’ on the planet, causing a temporary bulge on the planet as it passes. This has effects on Earth, such as tides. Over time, the energy created by the bulge is transferred from the planet to the moon, pushing it further and further. Our Moon, for example, moves 3.8 centimeters from Earth each year.
As well; so are other moons with respect to their host planets. Titan is one of the largest moons of Saturn, and also one of the most studied. But scientists have just discovered that the speed at which Titan is moving away from the ringed planet is much faster than they thought: a hundred times faster, about 11 centimeters a year. This finding has been issued in a statement by NASA and published on June 8 in Nature Astronomy , after its researchers contrasted data from the Cassini spacecraft.
What does this information give us?
In addition to allowing us to learn more fascinating details about our solar system, and how they might influence us from Earth, this discovery may help address a very old question: while scientists know that Saturn formed 4.6 billion years ago in the In the early days of the solar system, there is greater uncertainty about when the rings of the planet and its system of more than 80 moons formed. Titan is currently 1.2 million kilometers from Saturn. But its rate of rebound suggests that the moon was born much closer to Saturn, which would mean that the entire system expanded faster than previously believed.
On the other hand, the findings on the rate of the ‘drift’ of Titan also provide confirmation of a new theory that could explain and predict how the planets intervene in the orbits of their moons.
For the past 50 years, scientists have applied the same formulas to estimate how fast a moon is deviating from its planet, a rate that can also be used to determine the age of that moon. Those formulas and the classical theories on which they are based were applied to large and small moons throughout the solar system. They assumed that in systems like Saturn’s, with dozens of moons, outer moons like Titan migrated out more slowly than the closest moons, being further away from the strong gravity of their host planet.
But four years ago, theoretical astrophysicist Jim Fuller, now of Caltech, published research that reversed those theories. Fuller’s theory predicted that outer moons can migrate outward at similar speeds to inner moons because they all ‘lock’ in similar ways , depending on a particular planet’s wobble, which ‘flings’ them outward.
Fuller, who is also one of the authors of the discovery of the new rebound rate of Titan, states the following: “This type of planet-moon interactions may be more frequent than expected and can be applied to many other systems, such as exoplanets outside of our solar system, and even binary star systems, where stars orbit each other ”.
