For the first time, astronomers have measured the winds in Jupiter’s middle atmosphere, revealing unexpectedly fast flows in the deeper layers of the planet.
A paper published in Astronomy & Astrophysics gives a new meaning to the term “polar vortex”.
Using the Atacama Large Millimeter / Submillimeter Array (ALMA) matrix in Chile, astronomers recorded the speed of polar jets well below the cloud top, and, Wow, is it ever tasted down there. The fastest of these planes travels at 1,495 km / h, which is almost five times faster than the 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 that these planes, found under the main auroras of Jupiter (yes, Jupiter aurora, and they are quite amazing), they seem to be the lower tail of supersonic planes seen at 900 km [560 miles] above ”, as he explained in an e-mail. These currents could form a “huge anticyclone with a diameter of 3 to 4 diameters of the Earth and a vertical extent of 900 km,” said Cavalié, adding: “This is unique in the solar system.”
One statement launched by the European Southern Observatory, Cavalié described the new feature detected as a “unique weather beast”.
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Measuring wind speed under Jupiter’s upper atmosphere is not easy. The iconic red and white band that spins over Jupiter is usually used to measure winds in the upper layer, and the planet’s auroras, which are related to strong winds in the upper atmosphere, are also used as reference points. But to be honest, scientists haven’t really been able to measure the winds in Jupiter’s middle atmosphere – the stratosphere – so far.
Two measurements made these measurements possible: a famous comet and a very powerful telescope.
The comet in question is Shoemaker – Levy 9, which erupted in Jupiter in 1994. The impact has left distinct molecules in the atmosphere and 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 look under cloud tops and measure the speed of stratospheric jet streams.
To detect these molecules, the team used 42 of ALMA’s 66 high-precision antennas, marking the first time scientists have obtained such measurements in Jupiter’s middle atmosphere.
Specifically, ALMA data allowed scientists to measure small frequency changes in the radiation emissions of molecules as they are blown by winds in this part of the planet. In other words, they measured Doppler change. By doing so, “we were able to deduce wind speeds just as we could deduce the speed of a train passing through the changing frequency of the train’s whistle,” said Vincent Hue, a planetary scientist at Southwest Research Institute and co-author of the new study. , in the ESO statement.
These measurements showed that the winds under the aurora near the poles were moving at a speed of 895 mph, which is more than twice the speed of the winds that spin inside the planet’s Great Red Spot. To at the equator, stratospheric winds were recorded at an average speed of 600 km / h.
High-speed winds had previously been detected in the upper atmosphere, but scientists realized that the deeper you go, the slower you go in terms of wind speed. The new research suggests otherwise, a finding that came as a complete surprise to the team.
The newly detected winds are fast, but they are not the fastest in the solar system and they are not the fastest on Jupiter. Winds observed under Jupiter’s aurora are “twice as fast as the fastest winds measured at the top of Jupiter’s clouds,” Cavalié said. However, “above” 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 from 2,240 to 4,475 mph (3,600 – 7,200 km / h). Neptune, he added, “has the strongest winds in the solar system at the level of clouds and is 25% faster than the winds we measured under the aurora.”
This research, in addition to measuring the winds in Jupiter’s stratosphere, was done as proof of the concept for similar investigations to be carried out by the Submillimeter Wave Instrument (SWI) aboard the future. Jupiter Icy Moons Explorer (JUICE). The launch is scheduled for next year and will be the first European mission to Jupiter, with the expected arrival in about 10 years.