Bizarre hexagon circles Saturn's north pole | New 杏吧原创

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Bizarre hexagon circles Saturn’s north pole

A six-sided structure as wide as two Earths lies above the Ringed Planet's north pole and has remained curiously stable for more than 20 years

By Maggie Mckee

27 March 2007

A six-sided feature spanning 25,000 kilometres circles Saturn's north pole in this infrared image taken by Cassini — A six-sided feature spanning 25,000 kilometres circles Saturn鈥檚 north pole in this infrared image taken by Cassini
(Image: NASA/JPL/U Arizona)

An auroral ring (blue) adorns this image of the hexagon above Saturn's north pole, taken on 29 October 2006 from a distance of about 905,000 kilometres above the clouds — An auroral ring (blue) adorns this image of the hexagon above Saturn鈥檚 north pole, taken on 29 October 2006 from a distance of about 905,000 kilometres above the clouds
(Image: NASA/JPL/U Arizona)

A hurricane-like vortex swirls on Saturn's south pole, where towering clouds cast shadows around them — A hurricane-like vortex swirls on Saturn鈥檚 south pole, where towering clouds cast shadows around them
(Image: NASA/JPL/Space Science Institute)

A deep, hexagon-shaped feature lies above Saturn鈥檚 north pole, newly released images from the Cassini spacecraft reveal. The strange structure appears to be nearly stationary and may be a wave that stretches deep into the giant planet鈥檚 atmosphere.

NASA鈥檚 Voyager 1 and 2 spacecraft glimpsed parts of the feature nearly 30 years ago, but because of their viewing angle, they were not able to see the whole thing. Now, Cassini鈥檚 visual and infrared mapping spectrometer has captured the entire hexagon for the first time, thanks to a series of infrared images it took as the spacecraft flew over the pole in October and November 2006 (see Cassini snaps Saturn from a dizzying height).

The hexagon spans nearly 25,000 kilometres 鈥� the width of two Earths 鈥� and appears to be a clearing in the clouds that extends at least 75 km below the planet鈥檚 visible cloudtops. Watch a (4.2 MB, gif).

鈥淭his is a very strange feature, lying in a precise geometric fashion with six nearly equally straight sides,鈥� says team member Kevin Baines of NASA鈥檚 Jet Propulsion Laboratory in Pasadena, California, US. 鈥淲e鈥檝e never seen anything like this on any other planet.鈥�

Striking differences

In a statement, NASA says the feature may be 鈥渁n unusually strong pole-encircling planetary wave that extends deep into the atmosphere鈥�.

Saturn鈥檚 south pole also boasts a dramatic feature 鈥� a hurricane-like storm two-thirds as wide as the Earth (scroll down for image and see Spectacular storm rages on Saturn鈥檚 south pole).

鈥淚t鈥檚 amazing to see such striking differences on opposite ends of Saturn鈥檚 poles,鈥� says Bob Brown, leader of the Cassini visual and infrared mapping spectrometer at the University of Arizona in Tucson, US. 鈥淎t the south pole, we have what appears to be a hurricane with a giant eye, and at the north pole of Saturn we have this geometric feature, which is completely different.鈥�

Currently, the hexagon can only be detected at infrared wavelengths because it is winter in the northern hemisphere 鈥� a 15-year-long season in which sunlight does not fall on the pole. As spring begins to dawn in the region over the next two years, astronomers will search for the feature at visible wavelengths.

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