Do you know how long is a Saturn day?

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The new evidence of young rings lends credence to theories that they formed from a comet that wandered too close and was torn apart by Saturn's gravity - or by an event that broke up an earlier generation of icy moons.

This monochrome view is the last image taken by the imaging cameras on NASA's Cassini spacecraft.

Cassini was launched from Florida in 1997.

Cassini met a fiery end when it was deliberately steered into the planet in a suicidal "death dive" which took place in 2017.

The masses of Saturn's fainter D, F, G and E rings are considered negligible, the researchers wrote.

Some scientists previously believed the rings were formed along with the planet 4.5 billion years ago from icy debris which remained in orbit around it after the solar system formed.

Luciano Iess, from Sapienza University of Rome, Italy, and colleagues used data from the Cassini mission to analyze Saturn's gravitational field and the mass of its rings.

Scientists have discovered Saturn's rings are far younger than once thought, having formed as little as 10 million years ago.

Using new data from the now extinct Cassini mission, scientists led by the University of California-Santa Cruz found that a year on Saturn is 29 Earth years.

Scientists can also typically use the tilt of a planet's magnetic field to measure its day length.

"Based on the overall brightness, spectral characteristics, and geologic context, we attribute this new feature to specular reflections from a rain-wetted solid surface like those off of a sunlit wet sidewalk", the scientists who made the discovery explain.

Whatever happened, it's looking more and more likely that Saturn's splendid rings are a temporary phenomenon that humans are lucky to get to see at all. They estimate the rings to be about 40% of the mass of Saturn's moon Mimas, which is 2,000 times smaller than Earth's moon.

Saturn's interior is composed of three primary layers: a deep, inner rocky core made mostly of heavy elements, enveloped by liquid metallic hydrogen and surrounded by a thick layer of gaseous molecular hydrogen (H2). According to the new data, the core features a mass of roughly 15 to 18 Earth masses. The two forces pull the spacecraft in opposite directions.

The prevalence of dust storms and strong winds on Titan implies that the underlying sand can be moved as well and that the "giant dunes" that cover the moon's equatorial regions are constantly changing and still active. Scientists can measure a periodic signal in radio waves to get the rotation rate of these planets as they swing around while rotating.

The findings from Cassini's Radio Science Subsystem have also answered one other long-standing question about Saturn: the age of its rings.

Iess was especially excited by the measurements of the planet itself, which revealed that its gravitational field differed from initial expectations.

Before the age of the rings could be determined, NASA needed to know the mass of the rings to figure out how much material was held in them. Saturn has 62 known moons. "This is relatively short, compared to Saturn's age of over 4 billion years", James O'Donoghue, of NASA's Goddard Space Flight Center, said in a December statement.

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