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The Mystery of Titan’s Expanding Orbit:

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.

[...] So, what's going on? The answer may be a phenomenon broadly characterized as resonance-locking tidal theory. In essence, if the internals of a planet like Saturn get "strummed" at the right frequency by the gravitational pull of a moon there's an amplification of the tidal distortion—a kind of natural ringing, or resonance, of the thick gaseous envelope of the planet, and consequently more powerful gravitational interaction with the moon that's doing the strumming. And because the internal structure of a gas giant evolves over billions of years (because of things like gravitational contraction and helium rain) these resonances will change over time, sometimes "locking" onto different moons' orbital period and driving unexpectedly fast alterations in their orbits.

Journal Reference:
Valéry Lainey, Luis Gomez Casajus, Jim Fuller, et al. Resonance locking in giant planets indicated by the rapid orbital expansion of Titan, Nature Astronomy (DOI: 10.1038/s41550-020-1120-5)

Original Submission

1. "upstart" - https://soylentnews.org/~upstart/
2. "The Mystery of Titan’s Expanding Orbit" - https://www.scientificamerican.com/article/the-mystery-of-titans-expanding-orbit/
3. "has used measurements" - https://www.nature.com/articles/s41550-020-1120-5
4. "Cassini spacecraft" - https://www.jpl.nasa.gov/missions/cassini-huygens/
5. "10.1038/s41550-020-1120-5" - https://doi.org/10.1038/s41550-020-1120-5
6. "Original Submission" - https://soylentnews.org/submit.pl?op=viewsub&subid=42402

printed from SoylentNews, The Mystery of Titan's Expanding Orbit on 2024-04-24 13:30:06