Astronomers Directly Measure Winds In Jupiter's Middle Atmosphere For The First Time

European Southern Observatory (ESO) astronomers have used the Atacama Large Millimeter/submillimeter Array (ALMA) to directly measure winds in the middle atmosphere of Jupiter for the first time. Scientists analyzed the aftermath of a comet collision with Jupiter in the 1990s, and the research revealed incredibly powerful winds. Wind speeds are measured at up to 1450 kilometers an hour near Jupiter's poles.

Jupiter is well known for distinctive red and white bands in its atmosphere, which are swirling clouds of moving gas that are traditionally used for tracking wind in the lower atmosphere of the planet. Near the poles of the planet, astronomers have also seen a vivid glow known as aurorae that appear to be associated with strong wind in the planet's upper atmosphere. Researchers had previously been unable to directly measure wind patterns between those two atmospheric layers in the planet's stratosphere.

Measuring wind speed in the stratosphere of Jupiter using cloud-tracking techniques is impossible due to the absence of clouds in this part of the atmosphere. However, astronomers received an alternative tracking aid when comet Shoemaker-Leavy 9 collided with Saturn in 1994. That collision produced new molecules in the atmosphere of Jupiter that have been moving with the winds ever since.

The astronomers have been able to track one of those molecules, hydrogen cyanide, to measure stratospheric jets in Jupiter's atmosphere directly. Astronomers use the word "jets" to refer to narrow bands of wind in the atmosphere, which are similar to the jetstream on earth. Scientists have recorded strong jets with speeds of up to 400 meters per second located under the aurorae near the planet's poles. The wind speed of 1450 kilometers an hour is more than twice the maximum storm speed seen in the Great Red Spot and over three times the wind speed measured in the strongest tornadoes on Earth.