Saturn's day becomes shorter by five minutes

Canberra, July 30 (ANI): An analysis of Saturn's atmosphere has resulted in the definition of the planet's 'day' becoming shorter by five minutes.

According to the analysis, the time it takes the ringed behemoth to complete a spin on its axis is 10 hours, 34 minutes and 13 seconds, more than five minutes shorter than previous estimates.

Unlike a rocky planet, Saturn has no visual landmarks.

Instead, it is covered in clouds of gas driven by layers of jetstreams, making it hard to measure the planet's rotation.

As a result, astronomers have traditionally based their calculations on Saturn's magnetic field.

But, this signal can fluctuate and does not accurately measure how fast the planet's deep interior is rotating.

According to a report in ABC Science, Dr Andrew Prentice of Monash University in Melbourne said the problem with using Saturn's magnetic field is that it changes over time.

"It does not give a proper measure of Saturn's internal rotation since the magnetic field is slipping relative to the planet," he said.

"As a result, the period seems to have lengthened by seven to eight minutes since the time of the Voyager 1 and 2 missions in the mid-1980s," he added.

An international team led by scientists from Oxford University and the University of Louisville, Kentucky, used a different technique based on infrared images taken by the US spacecraft Cassini orbiting Saturn.

"We realised that we could combine information on what was visible on the surface of Saturn with Cassini's infrared data about the planet's deep interior and build a three-dimensional map of Saturn's winds," said Oxford professor Dr Peter Read.

"With this map, we were able to track how large waves and eddies develop in the atmosphere and from this come up with a new estimate for the underlying rotation of the planet," he added.

Read said that the fact that a Saturn day has been shortened by five minutes is a bigger deal than one might think.

"It implies that some of our previous estimates of wind speeds may be out by more than 160 miles (250 kilometres) per hour," he said.

"It also means that the weather patterns on Saturn are much more like those we observe on Jupiter, suggesting that, despite their differences, these two giant planets have more in common than previously thought," he added. (ANI)