Unlock the riddle of Jupiter’s red eye

Colossal vortex over 16,000 kilometers in diameter, the great red spot of Jupiter has intrigued scientists since its discovery respectively by Robert Hooke, in 1665, and by Jean-Dominique Cassini, the following year. While, on Earth, the lifespan of a hurricane rarely exceeds ten days, this titanic storm has been blowing continuously over the same region of the southern hemisphere for at least three hundred and fifty years.

With a diameter greater than that of the Earth, is this “anticyclone”, where winds turn (counterclockwise) at an average of 300 km / h, is it confined to the highest layers of the earth? atmosphere or is it rooted in the depths of the giant gas star? The NASA Juno mission team, which held a press conference on Thursday, October 28, has just provided an answer to this question. In four articles published in Science and the Journal of Geophysical Research : Planets et Geophysical Research Letters, these researchers explain how they were able to establish, from the data collected by the probe which arrived on site in 2016, that this disturbance is relatively superficial. In any case, it would be thinner than the famous structures in the form of colored bands visible in the images of Jupiter, the largest of the planets in the Solar System.

Read also Astronomy: the Juno probe has orbiting Jupiter

On Earth, the movements of the atmosphere are mainly governed by the combined effects of sunlight which heats the oceans and continents, the rotation of the planet and the condensation of water which causes the rains. “Jupiter has a mass 318 times greater, spins on itself in just ten hours and has no solid surface, explains Tristan Guillot, CNRS research director at the Côte d’Azur Observatory and co-investigator of the Juno mission. Jupiter also has the particularity of being made of 90% hydrogen and helium, that is to say chemical elements that are lighter than any condensation product… ”

Cyclonic and anticyclonic systems

And yet: through the eye of a telescope, similarities appear. Episodically, in the middle of the succession of bands, the clouds of ammonia and ammonium hydrosulphide which circulate at high altitudes, and give the celestial body its extraordinary hues, are organized in the form of cyclonic and anticyclonic systems. Below, powerful thunderstorms, fed by the condensation of water and accompanied by lightning, are unleashed. Some of these vortices eventually disappear. Others, like the big red spot, persist.

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Unlock the riddle of Jupiter’s red eye

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