Israeli researchers cut Saturn’s day short

Saturn. Credit: NASA/JPL/Space Science Institute.

(Israel Hayom/Exclusive to Israeli researchers have developed a computation method that has determined the exact length of one day on Saturn, or how long it takes for Saturn to make one full rotation.

Experts at Tel Aviv University and the Weizmann Institute of Science in Rehovot published a paper in the prestigious journal Nature on Wednesday, declaring that one Saturn day is 10 hours, 32 minutes, and 45 seconds long—approximately 6 minutes shorter than previously thought.

There was a disagreement between the data the Voyager spacecraft took when it flew past Saturn in the early 1980s and came up with 10 hours and 39 minutes, and the Cassini spacecraft, which traveled around the planet in 2004 and recorded a different figure: 10 hours and 47 minutes.

Unlike most other planets in our solar system, Saturn’s rotation is difficult to pinpoint thanks to its impenetrable gaseous atmosphere. While the solar system’s other gas giant, Jupiter, generates a magnetic field that sweeps around like the beam of a lighthouse, sending out radio waves that make it easy to measure how fast the hidden core spins under the gaseous atmosphere, Saturn’s magnetic and spin axes are aligned, making it difficult to determine the speed of the planet’s rotation.

The Israeli team approached the challenge using a technique called statistical optimization, in which they estimated the speed of the planet’s rotation according to its gravitational field, the density of the material and its flattened shape. It was using this technique that they arrived at the final figure of 10 hours, 32 minutes, and 45 seconds.

“We cannot fully understand Saturn’s internal structure without an accurate determination of its rotation period,” said Dr. Ravit Helled of Tel Aviv University.

Helled added, “We were determined to make as few assumptions as possible to get the rotational period. If you improve your measurement of Saturn’s gravitational field, you narrow the error margin.”

Posted on March 26, 2015 .