Methodical observations of Saturn’s weather patterns yield conclusive results for the Cassini imaging team. Thanks to the longevity of its orbit around Saturn, Cassini has gathered enough data to determine the reason for Saturn’s churning zonal jet streams.
Jet streams occur when temperature changes vary significantly across latitudes. These currents are what create the waving lines encircling Saturn. Images of these seemingly arbitrary fluctuations to both east and west were possible thanks to Cassini’s ability to observe the planet at lower altitudes.
Multiple theories on what makes waves in Saturn’s atmosphere stem from various possible energy sources: Either the planet’s heat or solar energy generates the thermal changes that move the air up and down like “the rotating gears driving a conveyor belt.”
By taking images through multiple filters Cassini gathered the necessary data to determine that the planet’s thermal energy was creating the storms and fluctuations causing the jet streams.
The first filter takes images in near-infrared light through a filter insensitive to methane absorption; another captures deeper images “at the tops of ammonia ice clouds, where solar heating is weak but closer to where weather originates.” Using an automated cloud tracking software, the imaging team analyzed the data from hundreds of photos to determine the causation of these weather patterns.
“With our improved tracking algorithm we’ve been able to extract nearly 120,000 wind vectors from 560 images, giving us an unprecedented picture of Saturn’s wind flow at two independent altitudes on a global scale,” said John Barbara, a part of the Cassini imaging team and co-publisher of the new study, in a NASA press release.
Observing the deceleration of the jet streams at higher altitudes—where according to the theory of solar powered jet streams, the sun’s rays would have increased acceleration—and the subsequent acceleration closer to the surface of the planet, scientists were able to deduce the correct hypothesis. They believe that internal generation of condensation and heat are responsible for the colossal jet streams.
Discounting the importance of the sun’s role in generating Saturn’s weather patterns provides a counterpoint to our own weather system, which is reliant upon the sun to generate storms and rain. Instead, Saturn’s atmosphere relies upon the heating of condensation to create massive storms that mark the planet’s appearance.