January 7, 1998: Here is the picture of Saturn taken by the Hubble telescope in ultraviolet light. The glowing, swirling material at Saturn's poles is its auroral "curtains," rising more than a thousand miles above the cloud tops.
Saturn's auroral displays are caused by an energetic wind from the Sun that sweeps over the planet, much like Earth's aurora, which is occasionally seen in the nighttime sky. The process that triggers these auroras is similar to the phenomenon that causes fluorescent lamps to glow.
Credits: J.T. Trauger (Jet Propulsion Laboratory) and NASA.