Jupiter is one of the best-studied planets in the Solar System, and yet the gas giant is still hiding plenty of surprises and mysteries. One was discovered at a distance, thanks to the keen infrared eye of JWST. There is a high-speed jet stream over Jupiter’s equator about 40 kilometers (25 miles) above the main cloud decks.
The jet stream is over 4,800 kilometers (3,000 miles) wide and its winds are moving at a speed of 515 kilometers (320 miles) per hour. That’s twice as fast as a Category five hurricane and a fair bit faster than the strongest gust of wind ever recorded on Earth. And before JWST, astronomers had no idea it was there.
“This is something that totally surprised us,” lead author Ricardo Hueso of the University of the Basque Country in Bilbao, Spain, said in a statement. “What we have always seen as blurred hazes in Jupiter’s atmosphere now appear as crisp features that we can track along with the planet’s fast rotation.”
The stream is confined to plus or minus three degrees from the equator. JWST’s infrared capabilities allow us to measure hazes that sit far above the clouds. The research team compared the observations from JWST to the views from Hubble that come from deeper in the atmosphere. By comparing the motion of the two layers, they could work out how fast the jet stream was moving.
And that is not all. The combination of the two data sets allowed the researchers to follow the development of convective storms around the equator of Jupiter. These are unrelated to the jet stream but go to show the power of different observatories working in tandem. And the team plans to keep following these weather phenomena.
“Jupiter has a complicated but repeatable pattern of winds and temperatures in its equatorial stratosphere, high above the winds in the clouds and hazes measured at these wavelengths,” explained team member Leigh Fletcher of the University of Leicester in the United Kingdom. “If the strength of this new jet is connected to this oscillating stratospheric pattern, we might expect the jet to vary considerably over the next two to four years – it’ll be really exciting to test this theory in the years to come.”
“It’s amazing to me that, after years of tracking Jupiter’s clouds and winds from numerous observatories, we still have more to learn about Jupiter, and features like this jet can remain hidden from view until these new NIRCam images were taken in 2022,” continued Fletcher.
The paper is published in the journal Nature Astronomy.