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Saturn’s moon Titan drifting away faster than previously expected

The moon starts drifting away from its host planets because as a moon orbits, its gravity pulls on a planet which causes a temporary bulge in the planet as it passes.

Jun 9, 2020 15:25 IST
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A research done by NASA scientists and the Italian Space Agency has made implications for the entire Saturn system as well as other moons and planets.

Scientists had earlier thought that they knew the rate at which the Saturn’s moon Titan has been moving away from its host planet but as per a discovery with data from NASA’s Cassini Spacecraft, it has been found that Titan is drifting hundred times faster than previously understood. It is about 4 inches (11 centimeters) every year.

Our moon has also been drifting away from Earth a tiny bit more each year, other moons have also been doing the same with their host planets.

Why the moon drifts away from their host planets?

The moon starts drifting away from its host planets because as a moon orbits, its gravity pulls on a planet which causes a temporary bulge in the planet as it passes.

With time, the energy created by subsiding and bulging, transfers from the planet to the moon and nudging it farther and farther out. Our own moon drifts 1.5 inches (3.8 centimeters) from the Earth each year.

What does this new finding mean?

While scientists have known that Saturn was formed 4.6 billion years ago in the early days of the solar system, there has been more of an uncertainty about the planet’s rings and when its system of more than 80 moons was formed.

Titan is currently 1.2 million kilometers (7,59,000 miles) from Saturn. The revised date of the drift has suggested that the moon started out much closer to Saturn, meaning that the whole system expanded more quickly than previously believed.

As per Valery Lainey, the lead author of the work published in Nature Astronomy, this result brings an essential new piece of the puzzle for the highly debated question of the age of Saturn system and how its moons were formed.

Lainey had conducted the research as a scientist at NASA’s Jet Propulsion Laboratory which is in Southern California before joining the Paris Observatory at PSL University.

Titan’s drift confirms new theory:

The findings that identify the Titan’s rate of drift has also provided an important confirmation of a new theory that predicts and explains how the planets affect their moon’s orbits.

Scientists have applied the same formula for the last 50 years to estimate how fast a moon drifts from its planet. This rate can also be used to determine the moon’s age. These classical theories and formulas on which they were based were applied to the moon’s large and small all over the solar system.

These classical theories assumed that in systems such as Saturn’s, which has dozens of moons, the outer moons like Titan migrates outward more slowly than the moons closer in because they are farther from the gravity of their host planet.

But four years ago, Jim Fuller, a theoretical astrophysicist, now of Caltech had published research that upended those theories. Fuller’s theory had predicted that outer moons can migrate outward at a similar rate as to the inner moons because they become locked in a different form of orbit pattern that links to the particular wobble of the planet and slings the moon outward.

Fuller, a co-author of the new paper, stated that the new measurements have implied that these kinds of planet-moon interactions can be prominent that prior expectations and that they can also apply to many systems such exoplanets- those outside our solar system, other planetary moon systems, and even binary star systems, where stars orbit each other.

In order to reach the results, the author had mapped stars in the background of Cassini images and had tracked Titan’s position. They also compared them with an independent data set: radio science data collected by Cassini, in order to confirm their findings.

The spacecraft sent radio waves to the Earth, during ten close flybys between 2006 and 2016. Scientists then studied how the signal frequency had changed by their interactions with their surroundings in order to estimate how Titan’s orbit evolved.

Co-Author Paolo Tortora, of the Italy’s University of Bologna, who is also the member of the Cassini Radio Science Team and had worked on the research with the support of the Italian Space Agency mentioned that by using two completely different datasets, the results obtained were in full agreement and were also in agreement with Jim Fuller’s theory that predicted a much faster migration of Titan.