Saturn is the sixth planet in the Solar System from the Sun and a planet that hosts immense thunderstorm that can encircle it whole. Dubbed "Great White Spots," these fearsome megastorms erupt biennially, persisting for months.
Astronomers have observed six such global storms on Saturn since 1876. The latest, in December 2010, was conveniently witnessed by NASA's Cassini spacecraft during its 200-day existence.
Impact of Megastorms Last for Centuries
Recent investigations into the monumental 2010 storm reveal that its 200-day tumult is merely a fraction of a broader, more peculiar meteorological picture. Via recent radio telescope scans, the enduring impacts of megastorms that erupted on Saturn over a century ago continue to influence the planet's atmosphere today, marked by persistent unexplained chemical irregularities.
Essentially, even long after the visible signs of a megastorm have dissipated, its atmospheric influence on Saturn endures for centuries. The naked eye often perceives Saturn's atmosphere as mostly unremarkable, in contrast to Jupiter's vivid aspect. However, this perception undergoes a profound shift when viewed through a radio lens.
Scientists used the Very Large Array radio telescope in New Mexico in their study, titled "Long-lasting, deep effect of Saturn's giant storms" published in Science Advances, to discern the chemical traces of the expansive 2010 megastorm amidst Saturn's upper atmospheric haze.
Astonishingly, they detected remnants from all six documented megastorms, spanning back over 130 years, alongside a potentially novel, previously unrecorded storm.
Manifesting exclusively in radio wavelengths, these remnants appeared as significant anomalies in ammonia gas. Saturn's upper cloud layer primarily comprises ammonia-ice clouds.
However, the radio observations unveiled regions of notably diminished ammonia concentrations just beneath this cloud layer, coinciding with past storm sites. Interestingly, far below these atmospheric zones, ammonia concentrations spiked well beyond normal levels.
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Megastorms Could Be Driving Mysterious Ammonia Transport in the Atmosphere
The study authors suggest that megastorms may initiate an enigmatic process that transports ammonia gas from Saturn's upper atmosphere to its lower depths.
The process could involve an unusual rain pattern resembling "mushball" precipitation, where icy ammonia hailstones descend through the atmosphere before vaporizing again. This mushy process seems to persist for centuries after the storm's visible disappearance.
While the mechanics behind these atmospheric anomalies, as well as Saturn's megastorms in general, remain elusive, delving deeper into their study has the potential to enhance comprehension not only of the formation of massive planets but also of the forces driving the expansion of enigmatic storm systems like Saturn's Great White Spots and Jupiter's even larger Great Red Spot.
Lead author of the study, Cheng Li, formerly associated with the University of California, Berkeley and now an assistant professor at the University of Michigan, said in a news release that understanding the mechanisms that govern the most megastorms in the Solar System puts the hurricane theory in a more expansive cosmic framework. This endeavor challenges existing understanding and stretches the boundaries of earthly meteorology.
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