PARIS (AFP) - A day on Saturn is pretty short, and it just got shorter. The time it takes the beringed behemoth to complete a spin on its axis has just been calculated by astrophysicists at 10 hours, 34 minutes and 13 seconds, more than five minutes shorter than previous estimates. A planet comprising clouds of gas driven by layers of mighty jetstreams, Saturn has no lasting visual landmarks as a rocky planet does, and this lack makes it hard to measure the planets rotation. As a result, astronomers have traditionally based their calculations on Saturns magnetic field. But this signal can fluctuate and does not accurately measure how fast the planets deep interior is rotating. 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. Their paper was released on Wednesday by Nature, the British-based science journal. We realised that we could combine information on what was visible on the surface of Saturn with Cassinis infrared data about the planets deep interior and build a three-dimensional map of Saturns winds, said Oxford professor 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. Read said that a day which had shortened by five minutes was a bigger deal than one might think. It implies that some of our previous estimates of wind speeds may be out by more than 250 kms 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.