Saturn’s South Pole is tilted toward the sun and is very hot. The hot spot was discovered by the W.M. Keck Observatory in Hawaii. Scientists believed the sun was the cause of the heat, but that’s not the reason. The Cassini spacecraft discovered the North Pole of Saturn is a hot spot too, even though it’s been out of sunlight and in winter since 1995.

The heat at both poles is a mystery. Scientists believe it is the result of air moving poleward, being compressed, and then heating up as it drops into the lowest part of the atmosphere called the troposphere. Scientists don’t know what the forces are driving the currents in Saturn’s atmosphere, but they know that both poles of Saturn have cyclonic vortexes. Cyclonic vortexes are violent, rotating windstorms that draw inward, toward their centers.

An unusual feature of the Northern Polar vortex is that it’s framed by a distinctive, long-lived polar hexagon that is still unexplained. The hexagon was first spotted in the 1980s by NASA’s Voyager 1 and 2 spacecraft. Cassini spacecraft’s infrared cameras detected the hexagon in deep atmospheric clouds in early 2007. The bright, warm hexagon is much higher in the atmosphere than scientists thought, and it extends to the top of the troposphere. The hexagon is associated with the downward current in the troposphere. Another mystery is both poles were depleted of phospine gas, a common gas on Saturn.

Scientists are curious about the dynamics of the giant gas planets. Neptune has a similar Southern Polar hot spot. Jupiter’s poles will be studied by NASA’s Juno mission, scheduled to launch in 2011 and arrive at Jupiter by 2016.