A team of scientistsfrom MIT has put forward a theory that would explain the presence ofenormous polar cyclones present on the gas giant Saturn. Thecyclones, first discovered by the Cassini spacecraft in 2008, are somassive that they could swallow the Earth in their expanse. Theresearch may even lead to better characterization of the atmosphereof distant exoplanets.
The element of thecyclones that has been baffling scientists since their discovery ishow they can come to exist in an environment such as that prevailingon Saturn. On Earth, cyclones are generated by heat and moisturecreated by our planet's oceans. These are prerequisites that areobviously lacking on Saturn – a gas giant which is predominantlycomposed of hydrogen and helium.
A team of scientistsfrom MIT believe that they may have found the answer. According tothe team, numerous relatively small thunderstorms occurring in theatmosphere of the ringed giant could have the effect of diverting airtowards the gas giant's polar regions, thanks to a phenomenon known asbeta drift.
"Each of these stormsis beta-drifting a little bit before they sputter out and die,"states lead author of a paper on the findings Morgan O’Neill says. "This mechanism means that little thunderstorms –fast, abundant, but not very strong thunderstorms – over a longperiod of time can actually accumulate so much angular momentum righton the pole, that you get a permanent, wildly strong cyclone."
The polar cyclonescurrently present on Saturn are believed to whip up winds in excessof 300 mph (483 km/h), and have persevered on the gas giant for many years. Tomake the discovery, the researchers created an atmospheric model andundertook numerous computer simulations that ran for hundreds ofdays.
The tests showed thatfor a polar cyclone to be present, there must be sufficient energy inthe atmosphere, or alternatively energy whipped up by minor storms inthe context of the size of the relevant planet. The larger theplanet, the more storms that must be present to trigger a cyclone.Jupiter for example is too massive for the small atmospheric stormsto generate a cyclone, but they may exist on Neptune.
If the theory iscorrect, astronomers may in the future be capable of gauging stormintensity in the atmosphere of distant exoplanets by observing thesize of polar cyclones.
A paper regarding theteam's findings has been published in the journal NatureGeoscience.
Source: MIT
