For the first time, astronomers have measured the winds inside Jupiter’s middle atmosphere, revealing unexpectedly fast currents in the deepest layers of the planet.
A paper published in Astronomy & Astrophysics is giving a new meaning to the term “polar vortex”.
Using the Atacama Large Millimeter / submillimeter (ALMA) matrix in Chile, astronomers have recorded the speed of polar rays well below the clouds, and wow, it sometimes bursts down there. The fastest of these planes moves at 1,440 km / h at 895 miles per hour, almost five times faster than the winds produced by the strongest hurricanes on Earth.
Thibault Cavalié, the lead author of the study and planetary scientist at the Laboratoire d’Astrophysique de Bordeaux in France, said that these jets, which are found in the main auroras of Jupiter (yes, Jupiter has auroras, and are quite impressive), appear to be the “lower tail of supersonic aircraft seen at 900 km [560 miles] above, “he explained in an email. These currents could form a” huge anticyclone with a diameter of 3 to 4 Earth diameters and a vertical extension of 900 km, “Cavalié said, adding:” This is unique to the solar system “.
In a statement published by the Southern European Observatory, Cavalié described the recently detected trait as a “unique meteoric beast.”
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Measuring wind speed below Jupiter’s upper atmospheric layer is not easy. The iconic red and white bands that scratch across Jupiter are often used to measure winds in the upper layer, and the planet’s auroras, which are tied to strong winds in the upper atmosphere, are also used as reference points. . But to be fair, so far scientists have not been able to measure winds in Jupiter’s middle atmosphere (the stratosphere).
Two things made these measurements possible: a famous comet and a very powerful telescope.
The comet in question is Shoemaker – Levy 9, which exploded against Jupiter in 1994. The impact left distinctive molecules in the atmosphere and they have been blowing around the gas giant for the past 27 years. The presence of these molecules, i.e. hydrogen cyanide, made it possible for Cavalié and his colleagues to look below the clouds and measure the speed of stratospheric currents.
To detect these molecules, the team used 42 of ALMA’s 66 high-precision antennas, marking the first time scientists have obtained these measurements in Jupiter’s middle atmosphere.
Specifically, ALMA data allowed scientists to measure small frequency changes in molecule emissions by radiation as winds blow them in this part of the planet. In other words, they measured Doppler displacement. In doing so, “we were able to deduce the speed of the winds in the same way that we could deduce the speed of a train going through the frequency change of the train’s whistle,” said Vincent Hue, a planetary scientist at the Southwest Research Institute and co-author of the new study, in the ESO statement.
These measurements showed that winds under the auroras near the poles were moving at 895 mph, which is more than twice the speed of winds swirling within the planet’s Great Red Spot. Towards 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 imagined it. the deeper you go the slower, in terms of wind speed. New research suggests the opposite, a finding that completely surprised the team.
Newly detected winds are fast, but they are not the fastest in the solar system, not even the fastest on Jupiter. The winds observed under Jupiter’s aurora are “twice as fast as the faster winds measured at the top of Jupiter’s cloud,” Cavalié said. “Above,” however, 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]”, O from 2,240 to 4,475 mph (From 3,600 to 7,200 km / h). Neptune, he added, “has the strongest winds in the solar system at the 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 a proof of concept for similar research that the Submillimeter Wave Instrument (SWI) would perform aboard the next Jupiter Icy Moons Explorer (SUC). The launch is scheduled for next year and will be the first European mission to Jupiter, with an expected arrival in about ten years.