High-resolution images collected by the Cassini probe have helped astronomers discover the broadest system of haze layers in the Solar System, located on Saturn. The images were used for this purpose by the Planetary Science Group at the University of the Basque Country.
A wide selection of meteorological phenomena happens in the extensive hydrogen atmosphere of Saturn, a planet approximately ten times the size of Earth. Those events help experts understand those that function in a similar way in our planet’s atmosphere.
The Hexagon-Shaped Peculiarity
Discovered among the phenomena is the renowned ‘hexagon,’ a unique wave structure that covers the planet’s polar area and whose form looks like it has been drawn by a geometrician.
First spotted back in 1980 by NASA‘s Voyager 1 and 2 probes, it has been monitored continuously since then, in spite of Saturn’s long and tough season cycles. Still, the wave remains almost static, meaning it barely moves according to the planet’s rotation, which is rather weird.
Cassini captured the image in June 2015 with its main camera, allowing researchers to see the hazes from the limb, located above the clouds in the shape of the hexagonal wave. The camera used many color filters, which enabled the composition of the hazes to be examined. To make the study more accurate, images collected by the Hubble Space Telescope 15 days later and depicting the hexagon from above were also used.
“The Cassini images have enabled us to discover that, just as if a sandwich had been formed, the hexagon has a multi-layered system of at least seven mists that extend from the summit of its clouds to an altitude of more than 300 km above them,” said Professor Agustín Sánchez-Lavega, who led the research. “Other cold worlds, such as Saturn’s satellite Titan or the dwarf planet Pluto, also have layers of hazes, but not in such numbers nor as regularly spaced out.”
The vertical scope of each haze layer is between about 7 and 18 kilometers (4 to 11 miles) thick, and as per the spectral examination, they have minute particles with radii of the order of 1 micron. Their chemical composition could include ice crystallites, such as acetylene, propyne, propane, diacetylene, or even butane when it comes to the highest clouds.
Another element analyzed by the team is the frequency of the vertical distribution of the hazes. The theory they came up with is that the hazes are placed by the vertical propagation of gravity waves that create changes in the thickness and temperature of the atmosphere, an event that takes place on Earth and on other planets.
The researchers also considered the possibility that it could be the dynamics of the hexagon itself and its strong jet stream that may be the cause of the formation of the gravity waves. On Earth, waves of this kind created by the oscillating jet stream moving at speeds of 100 km/h (62 mi/h) from West to East in the mid-latitudes have been spotted as well.
The phenomenon could be akin on both planets, although the oddities of Saturn mean that it is the only case seen so far in the Solar System. This is an aspect that has to be examined further.