“Cassini gazed toward high southern latitudes near Saturn’s south pole to observe ghostly curtains of dancing light — Saturn’s southern auroras, or southern lights. These natural light displays at the planet’s poles are created by charged particles raining down into the upper atmosphere, making gases there glow.
The dark area at the top of this scene is Saturn’s night side. The auroras rotate from left to right, curving around the planet as Saturn rotates over about 70 minutes, compressed here into a movie sequence of about five seconds. Background stars are seen sliding behind the planet. Cassini was moving around Saturn during the observation, keeping its gaze fixed on a particular spot on the planet, which causes a shift in the distant background over the course of the observation. Some of the stars seem to make a slight turn to the right just before disappearing. This effect is due to refraction — the starlight gets bent as it passes through the atmosphere, which acts as a lens. Random bright specks and streaks appearing from frame to frame are due to charged particles and cosmic rays hitting the camera detector.”
Video credit: NASA