For the first time ever, astronomers have measured winds in Jupiter’s central atmosphere, which reveal unexpectedly fast jets in the deeper layers of the planet.
A paper published in Astronomy & Astrophysics, gives the term “polar vortex” new meaning.
Using the Atacama Large Millimeter / Submillimeter Array (ALMA) in Chile, astronomers clocked the velocity of polar jets far below the cloud tops, and Wow, is it ever flurry down there. The fastest of these rays travels at 1,440 km / h (1,440 km / h), which is almost five times faster than winds produced by the strongest hurricanes on earth.
Thibault Cavalié, lead author of the study and a planetary scientist at the Laboratoire d’Astrophysique de Bordeaux in France, said these jets, found among Jupiter’s most important auroras (yes, Jupiter has auroras, and they are quite astonishing), appears to be the “lower tail of the supersonic jets seen 900 km [560 miles] above, ”as he explained in an email. These currents can form an ‘enormous anticyclone with a diameter of 3 to 4 diameters of the earth and a vertical range of 900 km’, said Cavalié, to which he said: ‘It is unique in the solar system.’
In a statement set by the European Southern Observatory, Cavalié describes the newly discovered feature as a ‘unique meteorological animal’.
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Measuring wind speed below the upper atmospheric layer of Jupiter is not easy. The iconic red and white bands that line Jupiter are commonly used to measure winds at the upper layer, and the auroras of the planet, which are linked to strong winds in the upper atmosphere, are also used as reference points. But to be honest, scientists have so far not been able to really measure winds in the middle atmosphere of Jupiter – the stratosphere.
Two things made these measurements possible: a famous comet and a very powerful telescope.
The comet in question here is Shoemaker – Levy 9, which crushed Jupiter in 1994. The impact has left characteristic molecules in the atmosphere and they have been blowing around the gas giant for the past 27 years. The presence of these molecules – namely hydrogen cyanide – made it possible for Cavalié and his colleagues to peek under the cloud tops and measure the velocity of stratospheric jets.
To detect these molecules, the team used 42 of ALMA’s 66 high-precision antennas, the first time scientists have obtained such measurements in Jupiter’s central atmosphere.
The ALMA data enabled the scientists to measure small frequency changes in the radiation emissions of molecules as they blow through winds in this part of the planet. In other words, they measured the Doppler shift. By doing so, ‘we could deduce the velocity of the wind as one could deduce the velocity of a passing train by changing the frequency of the train whistle’, explains Vincent Hue, a planetary scientist at Southwest Research Institute. and a co-author of the new study in the ESO statement.
These measurements showed that winds move under the auroras near the poles at 895 km / h, which is more than twice the speed of winds within the Great Red Spot of the planet. On the way the equator, stratospheric winds were clocked at an average speed of 373 mph (600 km / h).
High-speed winds have previously been detected at the upper atmospheric layer, but scientists have realized the deeper you go, the slower you go, in terms of wind speed. The new research indicates otherwise, a finding that the team was a total surprise.
The newly spotted winds are fast, but they are not the fastest in the solar system, nor are they the fastest on Jupiter. The winds observed under Jupiter’s aurora are ‘twice as fast as the fastest winds measured at Jupiter’s cloud top,’ Cavalié said. ‘Higher up’, and ‘still below the aurora in a layer called the ionosphere’, there are ‘winds with supersonic speeds of 1 to 2 kilometers per second [0.62 to 1.24 miles per second], ”Or 2 240 to 4 475 mph (3,600 to 7,200 km / h). Neptune, he added, “has the strongest winds in the solar system at cloud level and is 25% faster than the winds we measured under the aurora.”
This research, in addition to measuring winds in Jupiter’s stratosphere, was done as evidence of concept for similar investigations conducted by the Submillimeter Wave Instrument (SWI) aboard the upcoming Jupiter Icy Moons Explorer (JUICE). The launch is scheduled for next year, and it will be the first European mission to Jupiter, with an arrival of about ten years.