Perfect Timing on Saturn: Student Discovers Process Behind Planet's Seasons

What time is it? On Saturn, that's a tricky question. Before now, researchers were baffled about the changing seasons on the planet and what caused them. Now, an undergraduate student has discovered that a process occurring on Saturn's magnetosphere is linked to these seasons and changes with them.

The planet's magnetosphere is the third largest structure in the solar system, only eclipsed by the magnetic fields of the sun and Jupiter. Unlike Earth, which has a visible rocky surface and rotates once every 24 hours, Saturn is composed mostly of clouds and liquid gas layers. These layers each rotate about the planet at its own rate of speed. Because of all of these different rotating layers, it's hard for scientists to pin down time for the planet.

That's not to say that scientists haven't found out something about Saturn's timing. Using data from NASA's Cassini spacecraft, UI space physicist Donal Gurnett showed that the north and south poles of the planet have their own Saturn kilometric radiation (SKR) "days" that can vary over periods of weeks to years. SKR is a naturally occurring radio signal on the planet. Exactly how these different periods were determined through the magnetosphere, though, has remained a mystery.

Now, undergraduate student Tim Kennelly may have discovered the answer. He analyzed the activity generating the SKR emission relatively near the planet and the periodic signatures in Saturn's magnetosphere stretching millions of miles downstream to the planet's magnetotail. In the end, he discovered how these two phenomena might be linked.

First, he looked at inward-moving "flux tubes" that were composed of hot, electrically charged gas, called plasma. Focusing on the tubes when they initially formed and before they had a chance to dissipate, Kennelly found that the appearance of the tubes correlated with the activity in the northern and southern hemisphere depending on the season. In essence, he discovered that these tubes seemed to influence the time on Saturn.

The discovery could allow researchers to better understand not only Saturn, but also Earth. Our planet also possess a magnetosphere, and the Van Allen radiation belts affect a variety of activities on Earth ranging from space flight safety to satellite and cell phones communications.

The findings are published in the Journal of Geophysical Research Space Physics.