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posted by martyb on Tuesday June 09 2020, @01:49PM   Printer-friendly
from the drifting-away dept.

Saturn's Moon Titan Drifting Away Faster Than Previously Thought

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.

"This result brings an important new piece of the puzzle for the highly debated question of the age of the Saturn system and how its moons formed," said Valery Lainey, lead author of the work published June 8 in Nature Astronomy. He conducted the research as a scientist at NASA's Jet Propulsion Laboratory in Southern California before joining the Paris Observatory at PSL University.

cf: tidal acceleration:

Tidal acceleration is an effect of the tidal forces between an orbiting natural satellite (e.g. the Moon), and the primary planet that it orbits (e.g. Earth). The acceleration causes a gradual recession of a satellite in a prograde orbit away from the primary, and a corresponding slowdown of the primary's rotation. The process eventually leads to tidal locking, usually of the smaller first, and later the larger body. The Earth–Moon system is the best-studied case.

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)


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  • (Score: 2) by looorg on Tuesday June 09 2020, @04:12PM (2 children)

    by looorg (578) on Tuesday June 09 2020, @04:12PM (#1005227)

    The distance between Earth and Titan is depending on each objects current orbital location somewhere between 1,200,217,664 km and 1,666,681,075 km. For simplicity lets take the closest distance possible, so that would be 120,021,766,400,000 cm away. So if it drifts away at 11 cm per year on some kind of perfect earth trajectory it would only take about 10,911,069,672,727 years -- give or take a few million years perhaps if it isn't exactly at the closest distance -- until it smashes into us in some kind of life ending extinction event -- possibly. So no need to start to panic just yet! We have time to prepare!

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  • (Score: 3, Touché) by DannyB on Tuesday June 09 2020, @06:13PM

    by DannyB (5839) Subscriber Badge on Tuesday June 09 2020, @06:13PM (#1005301) Journal

    A mere ten trillion years to prepare?

    We'll squander it. Just watch. Revisit this SN post when it is too late.

    Meanwhile, our sun will become a red gnat or ant or something well before that. That will take us by surprise while we continue preparations for the collision with Titan.

    I'll be back to this SN post to revisit our progress in one quarter of a galactic rotation.

    But there will first be a sudden demand for Perl programmers to fix sites such as SN which need updating for current web standards. TCP/IP will be obsolete and new messaging standards will be based on the concept that information is piggybacked into advertising packets. All page content must be pure JavaScript 7, whose execution generates the page content.

    --
    The lower I set my standards the more accomplishments I have.
  • (Score: 2) by takyon on Tuesday June 09 2020, @11:31PM

    by takyon (881) <takyonNO@SPAMsoylentnews.org> on Tuesday June 09 2020, @11:31PM (#1005496) Journal

    If it's like our Moon, it would stop drifting after the Sun dies but well before the trillion year mark.

    https://www.forbes.com/sites/quora/2018/06/13/will-the-moon-ever-stop-drifting-away-from-earth/ [forbes.com]

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