The Cassini spacecraft has returned the best images yet of the strange hexagonal jet stream that flows around the northern pole of Saturn.

First discovered by the Voyager spacecraft in the early 1980s, the hexagon remains a beautiful mystery to astronomers, and one they've been waiting for another shot to see for almost three decades.

“The longevity of the hexagon makes this something special, given that weather on Earth lasts on the order of weeks,” said Kunio Sayanagi, a Cassini project researcher at the California Institute of Technology, in a NASA release. “It’s a mystery on par with the strange weather conditions that give rise to the long-lived Great Red Spot of Jupiter.”

The hexagon circles Saturn at 77 degrees north and is wider than two Earths. Nearly everything about the weather pattern is baffling. First, it's unclear what causes the hexagon. Second, it's bizarre that the jet stream would make such sharp turns. Earth's atmospheric movements rarely display such geometric rigor.

Fifty-five images were stitched together to create a three-frame animation of the jet stream on the move (see below). The sharp black triangle jutting out of the central black circle is an artifact of the image processing.

**

Images: NASA.

See Also:

WiSci 2.0: Alexis Madrigal's Twitter, Google Reader feed, and green tech history research site; Wired Science on Twitter and Facebook.**