I originally posted this article on February 20, 2009. I like the image a lot, and there’s a link to a cool animation of the hexagonal feature around Saturn’s north pole.

As Saturn’s spring approaches, its north pole comes into view and reveals the curious six-sided geometric shape rotating in its uppermost latitudes. This image was taken by Cassini one month ago. (The image was black-and-white….I colored it myself using the hues found in Saturn’s atmosphere. Click to see the original photo.)

The hexagonal feature is a phenomenon caused by the high wind speeds encircling the pole (300+ mph) and the convective heat processes from deep within the atmosphere, combined with the rotation of the giant gas planet. The hexagon appears to be a deep trough within the high layers of clouds, a clear channel extending 40-50 miles down into the atmosphere. It maintains its geometric shape even while strong winds and storms circle around it…watch it in motion here, filmed in heat-sensitive infrared on October 30, 2006.

This curious feature will be studied further as more of the pole comes into sunlight as Saturn progresses into its spring season. (Saturn’s seasonal rotation takes 29 Earth years to complete, so there’s plenty of time for study.)

Image credit: NASA/JPL/Space Science Institute