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Scientists Have Finally Figured Out How Long A Day On Saturn Is

The next time someone on the street says "hey you, exactly how long's a day on Saturn?", you won't have to stand there like a fool with no answer.

After decades of never quite knowing for sure, scientists have managed to determine a Saturn day is exactly 10 hours, 33 minutes and 38 seconds long, according to a paper published in The Astrophysical Journal

Though several estimates have been offered over the years, it's always been difficult to figure out exactly how long it takes the gas giant to complete a full rotation around its axis. And there are a couple of reasons for this.

Firstly, it has no solid surface with landmarks to track as it spins and secondly, its unusual magnetic field has largely hidden the planet's rotation rate from researchers.

But where the planet itself has failed to give up the secret, its trademark rings gave it away.

Using data from NASA's Cassini spacecraft, researchers discovered the rings respond to vibrations within the planet itself.

Basically, Saturn's rings are made up of solid bits of ice and rock which respond to vibrations within the planet similar to the way a seismometer responds to an earthquake.

"Particles throughout the rings can’t help but feel these oscillations in the gravity field," Christopher Mankovich, a graduate student in astronomy and astrophysics at University of California who studied the wave patterns explained.

"At specific locations in the rings these oscillations catch ring particles at just the right time in their orbits to gradually build up energy, and that energy gets carried away as an observable wave."

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By measuring these waves, Mankovich was able to develop models of Saturn's internal structure, thus allowing him to track its movements.

Previous estimates based on radio signals captured by the Voyager spacecraft in the 80s had the length of a Saturn day at 10 hours, 39 minutes and 23 seconds.

This estimate, however, was based on information about the planet's magnetic field. Unlike Earth and Jupiter's for example, Saturn's magnetic axis is nearly perfectly aligned with its rotational axis, making it nearly impossible to measure its rotation.

Saturn's rings, which are made of small, icy particles, are generally no thicker than the heigh of a house. Image: Getty/NASA

Scientists are excited to have finally pinned down a time frame they can rely on.

"The researchers used waves in the rings to peer into Saturn's interior, and out popped this long-sought, fundamental characteristic of the planet. And it's a really solid result," said Cassini Project Scientist Linda Spilker.

"The rings held the answer."

While a day on Saturn is less than half a day here on Earth, a year is as long as 29 Earth years.

The length of a day on each of our solar system's planets ranges from a mere 10 hours on Jupiter, all the way up to 5,832 hours on Venus.

Contact the author vquested@networkten.com.au