Halloween On Saturn: A Hex(agon) On You
A Hex(agon) On Saturn's North Pole
Coming up on Halloween, we take a look at one of the most bizarre and least understood features in the Solar System. Remember all the (non-scientific) hullabaloo over the Face on Mars?
Unfortunately, for Halloween fanatics, later higher resolution imaging revealed that the 'face' is just the contoured top of a mesa, probably the result of an old lava dome.
Then, an odd, six-sided, honeycomb-shaped feature circling the entire north pole of Saturn was discovered by NASA's Voyager spacecraft over twenty-five years ago. Now, the Cassini satellite has imaged this bizarre structure, indicating that it is a long-lived feature, like Jupiter's Giant Red Spot. The image was taken with Cassini's wide-angle camera on Nov. 27, 2012 using a spectral filter sensitive to wavelengths of near-infrared light centered at 7500 Å (750 nm).
"This is a very strange feature, lying in a precise geometric fashion with six nearly equally straight sides," exclaimed Kevin Baines, a member of Cassini's mapping spectrometer team at NASA's Jet Propulsion Laboratory (JPL), in Pasadena, Calif. "We've never seen anything like this on any other planet. Indeed, Saturn's thick atmosphere where convective cells dominate is perhaps the last place you'd expect to see such a six-sided geometric figure."
The hexagon is nearly 25,000 kilometers (15,000 miles) across. It extends deep down into the atmosphere, nearly 100 kilometers (60 miles) below the cloud tops. A jet stream is believed to move along the hexagon at around 100 meters per second (220 mph). But how do you get corners in a fluid flow?
Two scientists at the University of Oxford may have discovered part of the answer. Physicists Ana Aguiar and Peter Read decided to see if they could model the hexagon in their laboratory. They first placed a 30-liter cylinder of water on a slowly spinning table; the water represents Saturn's atmosphere spinning due to the planet’s rotation. Inside this tank, they placed two spinning disks that rotated more rapidly than the cylinder, creating a miniature "jet stream" that could be tracked using a green dye. By altering the rate at which the ring spun, the scientists could generate various shapes. "We could create ovals, triangles, squares, almost anything you like," says Read.
The bigger the difference in the rotation between the planet and the jet steam (represented by the cylinder and the ring respectively), the fewer sides the polygon had.
Although this experiment does not explain what force (magnetism?) is driving the hexagonal jet stream, the tantalizing results may yield real insight into what is producing this bizarre feature at Saturn's Northern Pole.
Coming up on Halloween, we take a look at one of the most bizarre and least understood features in the Solar System. Remember all the (non-scientific) hullabaloo over the Face on Mars?
Unfortunately, for Halloween fanatics, later higher resolution imaging revealed that the 'face' is just the contoured top of a mesa, probably the result of an old lava dome.
Then, an odd, six-sided, honeycomb-shaped feature circling the entire north pole of Saturn was discovered by NASA's Voyager spacecraft over twenty-five years ago. Now, the Cassini satellite has imaged this bizarre structure, indicating that it is a long-lived feature, like Jupiter's Giant Red Spot. The image was taken with Cassini's wide-angle camera on Nov. 27, 2012 using a spectral filter sensitive to wavelengths of near-infrared light centered at 7500 Å (750 nm).
"This is a very strange feature, lying in a precise geometric fashion with six nearly equally straight sides," exclaimed Kevin Baines, a member of Cassini's mapping spectrometer team at NASA's Jet Propulsion Laboratory (JPL), in Pasadena, Calif. "We've never seen anything like this on any other planet. Indeed, Saturn's thick atmosphere where convective cells dominate is perhaps the last place you'd expect to see such a six-sided geometric figure."
The hexagon is nearly 25,000 kilometers (15,000 miles) across. It extends deep down into the atmosphere, nearly 100 kilometers (60 miles) below the cloud tops. A jet stream is believed to move along the hexagon at around 100 meters per second (220 mph). But how do you get corners in a fluid flow?
Two scientists at the University of Oxford may have discovered part of the answer. Physicists Ana Aguiar and Peter Read decided to see if they could model the hexagon in their laboratory. They first placed a 30-liter cylinder of water on a slowly spinning table; the water represents Saturn's atmosphere spinning due to the planet’s rotation. Inside this tank, they placed two spinning disks that rotated more rapidly than the cylinder, creating a miniature "jet stream" that could be tracked using a green dye. By altering the rate at which the ring spun, the scientists could generate various shapes. "We could create ovals, triangles, squares, almost anything you like," says Read.
The bigger the difference in the rotation between the planet and the jet steam (represented by the cylinder and the ring respectively), the fewer sides the polygon had.
Although this experiment does not explain what force (magnetism?) is driving the hexagonal jet stream, the tantalizing results may yield real insight into what is producing this bizarre feature at Saturn's Northern Pole.
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