In 1980s, analysis of Saturnian radio emissions by NASA’s Voyager spacecrafts measured that a day (rotation period) on Saturn is 10 hours, 39 minutes and 22 seconds. But now, according to the lastest radio data collected by Cassini in 2003 and 2004 measured a different number, 10 hours, 45 minutes and 45 seconds. If this number is confirmed, this could help scientists gain a better understanding of Saturn’s turbulent atmosphere and its shrouded interior. The study, led by Giacomo Giampieri of NASA’s Jet Propulsion Laboratory, is detailed in the May 4 issue of the journal Nature.
The rotation period of a rocky planet like the Earth can be calculated by observing the motion of a particular spot on it. However, the solid core of Saturn is covered by thick clouds. Therefore, this measurement is not applicable.
Instead, the typically stated rotation periods for these planets are those of their magnetic fields, which scientists believe are closely tied to the rotations of their solid interiors.
But measuring the rotation period of Saturn’s magnetic field is difficult because its rotational axis — the imaginary line around which the planet rotates — is nearly identical to the axis around which its magnetic field revolves.
In contrast, the magnetic and rotational axes of Jupiter are separated by a few degrees and scientists can use this difference to calculate its rotation period.
It’s like measuring the spin rate of a CD that has a distinct label on it versus a blank one that doesn’t, Giampieri explained. “It’s very difficult to tell if a blank CD is rotating at all.”
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