An anonymous reader sends in a brief writeup about a massive storm that's been visible on Saturn's surface for a few months now. "As it rapidly expanded, the storm's core developed into a giant, powerful thunderstorm, producing a 3,000-mile-wide (5,000-kilometer-wide) dark vortex possibly similar to Jupiter's Great Red Spot." The storm has been photographed by the Cassini probe, Hubble and even amateur astronomers here on Earth. (The Planetary Society Weblog also posted an 8,000-pixel-wide panorama a while back.) "The violence of the storm — the strongest disturbances ever detected in Saturn's stratosphere — took researchers by surprise. What started as an ordinary disturbance deep in Saturn's atmosphere punched through the planet's serene cloud cover to roil the high layer known as the stratosphere." A study on the thermal structure of the storm (abstract) was just published in the journal Science.