NASA's Cassini spacecraft captures new images of the planet's freakish weather system.
Saturn’s giant, north-pole jet stream is known as “the hexagon” for its unusual shape. This image from NASA’s Cassini spacecraft captures the gas giant down to 70° latitude and covers 20,000 miles (35,000km) of its northern hemisphere. Along the hexagon’s boundaries, winds reach 220 mph (322 km/hr), while a massive storm rotates at its center.
While there are many storms in the solar system, there’s nothing exactly like the hexagon. Unimpeded by solid land masses, which interrupt storms’ progress on Earth and usually limit their existence to a few days, Saturn’s hexagon has possibly existed for decades. On Earth, we have hurricanes — a storm that resembles the one at the hexagon’s center — but those are dwarfed by the hexagon’s size.
The new Cassini images not only reveal smaller vortices inside the hexagon, but also the size, shape, and density. The colors chosen for this false-color rendering distinguish between types of particles: inside the hexagon there are fewer large haze particles but more small haze particles, while outside the hexagon, the opposite is true. The striking clarity is due to a 10-hour exposure and Saturn’s northern spring (which began in August 2009). By 2012 the Sun had illuminated more of the gas giant’s north pole than scientists had ever seen.
Some of the smaller vortices rotate in the opposite direction of the hexagon flow and are occasionally swept around by the jet stream. The largest of these spans 2,200 miles (3,500km) — only one-tenth the hexagon’s size but twice the size of the largest hurricane ever recorded on Earth.
For more information, read JPL's press release.