New analysis of data from NASA's Cassini spacecraft finds a viable explanation for what's keeping the upper layers of Saturn,and possibly the other gas giants, so hot: auroras at the planet's north and south poles. Electric currents, triggered byinteractions between solar winds and charged particles from Saturn's moons, spark the auroras and heat the upperatmosphere. (As with Earth's northern lights, studying auroras tells scientists what's going on in the planet's atmosphere.)The work, published today in Nature Astronomy, is the most complete mapping yet of both temperature and density of a gasgiant's upper atmosphere -- a region that has been poorly understood."Understanding the dynamics really requires a global view. This dataset is the first time we've been able to look at the upperatmosphere from pole to pole while also seeing how temperature changes with depth," said Zarah Brown, lead author of thestudy and a graduate student in the University of Arizona Lunar and Planetary Laboratory.By building a complete picture of how heat circulates in the atmosphere, scientists are better able to understand how auroralelectric currents heat the upper layers of Saturn's atmosphere and drive winds. The global wind system can distribute this
