The Cassini spacecraft recently photographed the most powerful storm (white swirl) ever observed on Saturn. The tempest is located in Storm Alley, a region of the planet’s southern hemisphere where strong disturbances have frequently occurred. From north to south, the storm spans 3,500 kilometers, about the distance from Salt Lake City to New York. Because most storms on Saturn lie below the clouds, only the strongest upwellings can be seen.
The storm erupted on Saturn’s night side, so the orbiting craft had to rely on the tiny amount of sunlight reflected off Saturn’s icy rings to record the disturbance. Cassini first detected signs of the storm on Jan. 23, when the craft recorded radio noise generated by lightning deep within Saturn’s atmosphere. Amateur astronomers using small, Earth-based telescopes took the first visible-light portraits. NASA released this Cassini image, taken Jan. 27, on Feb. 14. The storm intensified on Feb. 19.