Titan silhouetted against Saturn. Credit: Seen through the eyes of some omnipotent time traveler, our solar system—like any planetary system—is a heaving, pulsing thing. Across millions and billions of years its contents ebb and flow. Planetary orbits shift in shape and orientation, and billions of ancient asteroidal pieces shuffle through the skeletal disk that defines the major architecture of all that surrounds the sun, itself a star that sheds mass and energy as it gradually climbs an-ever brightening staircase of thermonuclear fusion.
But some things are assumed to be comparatively dull and unchanging. Saturn’s largest moon, Titan, for instance, was expected to sit in its orbit with little alteration to that position over the billions of years since its formation. Now a study published in Nature Astronomy by Lainey, et al., has used measurements from the Cassini spacecraft (which orbited Saturn from 2004 to 2017) to determine that Titan has an orbit that grows by an astonishing 11 centimeters each year.
The solution the authors propose to this new mystery rests in an intricate but powerful phenomenon that, if they are correct, could help us understand the grander history of moons around all giant worlds. To understand that, we have to […]
read more here —> www.scientificamerican.com