Saturn is the only ringed planet in the solar system. In the 1980’s, the rotation of the ringed planet was calculated on the basis of periodic changes in Saturn’s radio waves. The planets rotation was calculated to be in the order of 10 hours and 39 minutes. Decades later, the Cassini Orbiter calculated the rotation period as 10 hours and 47 minutes. The disparity in the calculation was glaring.

There is still bad news for science textbooks publishers as news is trickling in that Saturn’s rotation period is 6 minutes shorter than previously thought. The latest calculations have been made by planetary scientists at Tel Aviv University in Israel using the deduction of Saturn’s spin from its gravity field.

Scientists have unearthed the cause of this anomaly to the complex relation of Saturn’s magnetic field and its spin axes. Saturn spins very fast and this makes the equator bulge outwards which distorts the gravity field and this has been measured by Cassini.


Take the example of Jupiter’s magnetic tilts as compared to its spin axis. It is easier to detect the radio waves since the magnetic field acts much akin to the beam of a lighthouse which flashes radio waves instead of light. This makes it much easier to calculate the hidden planet’s spin rate.

Both Voyager and Cassini could not measure Saturn’s rotation period since the ringed planet aligned magnetic and spin axes. This made the measured period erroneous since it does not reflect the planet’s rotation.

Helled and his colleagues from the Tel Aviv University used an older technique to manually deduce the spins from Saturn’s own magnetic field and thus came up with the new figures of 10 hours 32 minutes and 45 seconds. The scientists published their findings in the journal Nature.

Dr. Helled said, “We came up with an answer based on the shape and gravitational field of the planet. We were able to look at the big picture, and harness the physical properties of the planet to determine its rotational period.”

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