The Cassini spacecraft is shown exploring Saturn and its magnetic field in this illustration. Saturn generates a strong magnetic field as it turns on its axis. The field is sculpted by solar radiation and the solar wind, which push the lines of magnetic force away from Saturn in a teardrop shape. Interactions between the field and particles of the solar wind produce weak radio waves, which Cassini has monitored. [ESA]
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Moon and Saturn
[SFX: Saturn radio emissions]
As the planet Saturn spins on its axis, it generates a powerful magnetic field. Interactions between the magnetic field and the solar wind — a steady flow of charged particles from the Sun — produce radio waves, like these recorded by the Cassini spacecraft. [more audio]
The radio waves can help scientists learn more about Saturn’s interior and motion. But the waves don’t always reveal what scientists expect.
At first, for example, they hoped the waves would reveal how fast Saturn turns on its axis. The planet’s thick atmosphere is in constant motion, so there are no steady features to use as markers to measure how fast Saturn turns. Since the magnetic field is generated by Saturn’s rotation, though, scientists thought patterns in the radio waves would reveal Saturn’s true rotation rate. Instead, the timing of these patterns varies by about one percent, and scientists are trying to understand why.
One thing they have discovered is that some changes in the radio waves appear to be tied to changes in seasons. A few years ago, when it was winter in the northern hemisphere of Saturn, the radio waves came from the northern part of the magnetic field. Now, with summer approaching, more of the waves come from the southern hemisphere — offering new mysteries for scientists to ponder.
Look for Saturn close to the upper right of the Moon as night falls. The giant planet looks like a bright golden star.
Script by Damond Benningfield, Copyright 2013