content long 26-September-2018 17:34:36

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16-18 years old: The hexagon at Saturn's north pole

 Author: Andrew Ng

I believe that of the three targets, an attempt to study the hexagon at Saturn’s North Pole is the most appropriate, as the least is known about the enigmatic hexagon.

On earth, weather conditions typically last for weeks at most, and even this is by no means a common occurrence. However, it is fascinating that the storm on Saturn measuring 13,800km across, larger than the size of the Earth, can exist for decades or even centuries. This immediately gives rise to the questions asked by many scientists: ‘How has it remained stable? What fuels it for so long?’ Moreover, another, arguably even more intriguing aspect of the hurricane, is its shape. A distinct hexagon can be made out in most photos of Saturn’s North Pole, and no one has been able to definitively answer the question of how it stably maintains this shape over such long periods of time.

Various theories have been proposed to explain this phenomenon, which cannot be found anywhere else in the solar system. One theory holds that the hexagon is a result of drastically different wind speeds that cause an area of turbulent flow, with a number of vortices being formed. These then interact until they reach an equilibrium where they are evenly spaced apart. This only occurs on Saturn’s North Pole because the viscosity and speed difference have to be within a certain range; on Saturn’s South Pole, for example, Hubble observed vortices and a hurricane with a colossal eye but no hexagon. Another theory asserts that it is due to a series of spiralling vortices which have not been observed, but by imposing certain conditions on the jetstream, including being slow and shallow, scientists were nevertheless able to accurately simulate the behaviour of the hurricane.

According to Kevin Baines, atmospheric expert and member of Cassini's visual and infrared mapping spectrometer team at NASA's Jet Propulsion Laboratory, ""Once we understand its dynamical nature, this long-lived, deep-seated polar hexagon may give us a clue to the true rotation rate of the deep atmosphere and perhaps the interior,"" Gaining insight into the pure fluid mechanics of the gases, without being subject to terrestrial influences, apart from being an alluring topic of research in itself will also help us understand our own planet, for example the hexagon’s jet stream keeping photochemical smog out of the interior has been likened to the way the ozone hole over Antarctica can’t be replaced because ozone is prevented from entering by the strong winds.

With the start of Saturn's northern spring in August 2009, sunlight has begun to bathe the planet's northern hemisphere, illuminating the previously dark north pole. This should make an attempt to study it more fruitful and useful to the scientific community compared to previous years. It is therefore that I believe now is the time for Cassini to turn its eyes on the hexagon.


Last Update: 19 May 2017

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