Saturn's rotation puts astronomers in a spin

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A new estimate of how fast Saturn spins has been made using magnetic data from NASA’s Cassini spacecraft – but it is not the answer scientists were expecting.

As a gas giant, Saturn’s rotation has been historically difficult to measure. Its hazy atmospheric features shift with respect to each other and cannot be used to clock the spin rate of the planet’s interior.

The most commonly cited figure for Saturn’s rotation period – 10 hours, 39 minutes and 22.4 seconds – was derived in 1980 from Voyager observations of radio waves generated by solar radiation hitting the planet’s atmosphere. Yet Cassini has returned a result almost 8 minutes longer, a difference that defies easy explanation.

"The knowledge of the rotation period is a very important ingredient when you try to model the interior of a planet like Saturn," says Giacomo Giampieri of NASA's Jet Propulsion Laboratory.

Source: New Scientist

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