Saturn’s hexagon: An amazing phenomenon

This colorful view from NASA’s Cassini mission is the highest-resolution view of the unique six-sided jet stream at Saturn’s north pole known as “the hexagon.”
Credit: NASA/JPL-Caltech/SSI/Hampton

An unusual structure with a hexagonal shape surrounding Saturn’s north pole was spotted on the planet for the first time thirty years ago. Nothing similar with such a regular geometry had ever been seen on any planet in the Solar System. The Planetary Sciences Group has now been able to study and measure the phenomenon and, among other achievements, establish its rotation period. What is more, this period could be the same as that of the planet itself. Saturn is the only planet in the Solar System whose rotation time remains unknown.

In 1980 and 1981 NASA’s Voyager 1 and 2 space probes passed for the first time over the planet Saturn, located 1,500 million km from the Sun. Among their numerous discoveries they observed a strange, hexagon-shaped structure in the planet’s uppermost clouds surrounding its north pole. The hexagon remained virtually static, without moving, vis-à-vis the planet’s overall rotation that was not accurately known. What is more, the images captured by the Voyager probes found that the clouds were moving rapidly inside the hexagon in an enclosed jet stream and were being dragged by winds travelling at over 400 km/h.

Thirty years later — the equivalent of one Saturn year, in other words, the time the planet takes to go all the way around the Sun — and over more than six consecutive years, researchers in the UPV/EHU’s Planetary Sciences Group, in collaboration with astronomers from various countries, were able to observe Saturn’s northern polar region in detail once again and confirmed that the hexagon continued in place. After measuring the positions of the hexagon vertices with great precision, they determined that its movement remains extremely stable, and on the basis of the cloud movements, that the jet stream inside it remains unchanged. For this study the researchers used images taken from Earth between 2008 and 2014; they used, among others, the astronomical cameras PlanetCam (developed by the Planetary Sciences Group itself) and Astralux, fitted to the telescopes of the Calar Alto Observatory in Almería (Spain); in addition, they used the very high resolution images obtained by t he Cassini spacecraft, which has been orbiting Saturn since 2004. More here Saturn’s hexagon: An amazing phenomenon

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