- Cameras aboard NASA's Cassini spacecraft have captured images of a mysterious hexagon-shaped cloud formation that is likely formed by the path of a jet stream flowing around the planet's north pole. The hexagon, which was discovered by the Voyager spacecraft in the early 1980s, encircles Saturn with an estimated diameter wider than two Earths. The associated jet stream likely whips along the hexagon at about 220 miles per hour (100 meters per second).
"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 imaging team associate at the California Institute of Technology. "It's a mystery on par with the strange weather conditions that give rise to the long-lived Great Red Spot of Jupiter." Hexagon in clouds on Saturn NASA / JPL / Space Science Institute / Space.com Cameras on NASA's Cassini spacecraft recorded this image of clouds on Saturn. The hexagon shape, which is likely the result of weather patterns, was first noticed in the early 1980s, and scientists are surprised it has lasted so long.
The last visible-light images of the entire hexagon were captured by NASA's Voyager spacecraft nearly 30 years ago, the last time spring began on Saturn. For the next 15 years, the north pole was shrouded in darkness.
Cassini has been orbiting Saturn since 2004, and unlike Voyager, it has a better angle for viewing the north pole and provides higher-resolution images. But the long darkness of Saturnian winter hid the hexagon from Cassini's visible-light cameras for years. During this time, the craft's infrared instruments were able to detect the shape using heat patterns, with the resulting images showing the hexagon is nearly stationary and extends deep into the atmosphere. The images also showed a hotspot and cyclone in the same region.
Just as the north pole emerged from winter in January, Cassini's cameras went to work. Imaging team scientists stitched together 55 images to create a mosaic and a three-frame movie.
The science team will search....
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