Saturn's rotation period revealed?

LONDON: In a thrilling revelation, scientists have ascertained the rotation period of the enigmatic hexagon-shaped structure in Saturn's uppermost clouds surrounding its north pole.

And the rotation period of the hexagon could be that of the planet itself, said the researchers.

Saturn is the only planet in the solar system whose rotation period is not yet known.

"The movement of the hexagon could be linked to the depths of Saturn, and the rotation period of this structure, which, as we have been able to ascertain, is 10 hours, 39 minutes and 23 seconds, could be that of the planet itself," said Agustan Sanchez-Lavega, head of the planetary sciences group at the University of the Basque Country (UPV/EHU) in Spain.

Researchers in the UPV/EHU's planetary sciences group, in collaboration with astronomers from various countries, observed Saturn's northern polar region in detail and confirmed that the hexagon continued in place.

Nasa's Voyager 1 and 2 space probes that passed for the first time over the planet Saturn in 1980 and 1981, discovered the hexagon-shaped structure in the planet's uppermost clouds.

After measuring the positions of the hexagon vertices with great precision, the researchers in the UPV/EHU's planetary sciences group 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 the 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 Almeraa (Spain).

They used the very high resolution images obtained by the Cassini spacecraft, which has been orbiting Saturn since 2004.

The UPV/EHU researchers suggest that the hexagon and its stream are the manifestation of a "Rossby wave" similar to those that form in the mid-latitudes of the earth.

On Saturn, "the hexagonal wavy motion of the jet stream is expected to be propagated vertically and reveal to us aspects of the planet's hidden atmosphere", Sanchez-Lavega pointed out.