NASA | JPL-Caltech | Cassini | 2020 Jun 08
The new research by scientists at NASA and the Italian Space Agency has implications for the entire Saturn system as well as other planets and moons.
Just as our own Moon floats away from Earth a tiny bit more each year, other moons are doing the same with their host planets. As a moon orbits, its gravity pulls on the planet, causing a temporary bulge in the planet as it passes.
Over time, the energy created by the bulging and subsiding transfers from the planet to the moon, nudging it farther and farther out. Our Moon drifts 1.5 inches (3.8 centimeters) from Earth each year.
Scientists thought they knew the rate at which the giant moon Titan is moving away from Saturn, but they recently made a surprising discovery: Using data from NASA's Cassini spacecraft, they found Titan drifting a hundred times faster than previously understood - about 4 inches (11 centimeters) per year.
The findings may help address an age-old question. While scientists know that Saturn formed 4.6 billion years ago in the early days of the solar system, there's more uncertainty about when the planet's rings and its system of more than 80 moons formed. Titan is currently 759,000 miles (1.2 million kilometers) from Saturn. The revised rate of its drift suggests that the moon started out much closer to Saturn, which would mean the whole system expanded more quickly than previously believed. ...
Titan is Migrating Away from Saturn 100
Times Faster than Previously Predicted
California Institute of Technology | 2020 Jun 08
Resonance Locking in Giant Planets Indicated by the Rapid Orbital Expansion of Titan ~ Valéry Lainey et al
- (online 08 Jun 2020) DOI: 10.1038/s41550-020-1120-5