Astronomers measured the winds in Jupiter’s stratosphere for the first time and discovered ultra-fast jet streams. Using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, speeds were clocked at 895 miles per hour—that’s about five times faster than Earth’s strongest hurricanes and twice as fast as the planet’s Great Red Spot.
Thibault Cavalié, lead author of the paper published in Astronomy & Astrophysics and planetary scientist at the Laboratoire d’Astrophysique de Bordeaux in France noted that the jets were found under Jupiter’s polar auroras and are the “lower tail of the supersonic jets seen 900km (560 miles) above,” and that the currents could form a “huge anticyclone with a diameter of 3 to 4 Earth diameters and a vertical extent of 900 km. This is unique in the solar system.” Cavalié also noted in a statement from the European Southern Observatory that the jet streams are a “unique meteorological beast.”
Unlike Jupiter’s top layer, which features the gas giant’s famous red and white bands, the Great Red Spot, and the auroras, the jets were much more difficult to measure and study. Finally, scientists were able to capture this reading thanks to a famous comet and Chile’s powerful telescope.
The comet—Shoemaker-Levy 9—smashed into Jupiter in 1994, and its impact left unique hydrogen cyanide molecules to blow around in the planet’s atmosphere. These molecules are what allowed Cavalié and his colleagues. The team used 42 of ALMA’s 66 high-precision antennas to detect the molecules and measure their frequency changes in their radiation emissions as they are blown around, which is to say they measured the Doppler shift.
By focusing on this measurement, “we were able to deduce the speed of the winds much like one could deduce the speed of a passing train by the change in the frequency of the train whistle,” said Vincent Hue, co-author of the study and planetary scientist at the Southwest Research Institute in the earlier ESO statement.
The study revealed that the stratospheric winds underneath Jupiter’s auroras were whipping around at 895 miles per hour. Towards the planet’s equator, these same winds moved a little more slowly, at just 373 miles per hour (600kilometers per hour). Scientists already knew of the fast winds on Jupiter’s top layers and previously believed that as you moved further into the planet, the slower the winds would get. This new data turns that theory on its head and completely surprised Cavalié’s team.
What’s really exciting is that, while Jupiter’s stratospheric winds are fast, they are far from the fastest in our solar system or even on the rest of the planet. In Jupiter’s ionosphere, a layer of the atmosphere closer to the planet’s exterior, there are supersonic winds that rush at 1-2km per second (0.62-1.24 miles per second) or 3,600-7,200 kilometers per hour (2,240-4,475 miles per hour). Neptune holds the solar system record, however, with winds that are 25% faster than those measured underneath Jupiter’s aurora.