Jupiter’s atmosphere is a fascinating, ever-changing environment. Bands of different colors, storms, and giant clouds can be seen all over the planet. But its upper atmosphere has long been thought to be tranquil. It’s certainly where the polar auroras originate, but other than that, it was believed that nothing strange was going on there. Now, a group of astronomers has overturned that belief.
The upper atmosphere is difficult to study. At the poles, particles from the volcanic moon Io align with magnetic field lines, creating auroras of different wavelengths. For the rest of Jupiter, the energy that drives them comes from sunlight, which receives only about 4 percent of the sunlight that Earth does. So astronomers have assumed Jupiter is very uniform.
“We thought, perhaps naively, that this area would be really boring,” said team leader Henrik Melin of the University of Leicester in the UK. statement“In fact, it’s just as fascinating, if not more so, than the Northern Lights. Jupiter continues to surprise us.”
The JWST observations revealed complex structures above the iconic Great Red Spot, a storm larger than Earth, finding dark arcs and bright patches visible in infrared light, with the source of the variations not sunlight but a turbulent layer deeper in Jupiter’s atmosphere.
“One way this structure is altered is by gravity waves, which are similar to waves crashing on a beach, creating ripples in the sand,” Melin explains. “These waves originate deep in the turbulent lower atmosphere around the Great Red Spot and travel up in altitude, altering the structure and emissions of the upper atmosphere.”
Such gravitational waves also exist on Earth, but if the mechanism at work is the same, the waves are much weaker.
The discovery has been a long time coming: astronomers have long been intrigued by Jupiter’s upper atmosphere, and the observations were made as part of the JWST’s Early Release Science program (ERS).
“This ERS proposal was written in 2017,” says team member Imke de Pater of the University of California, Berkeley, “and one of our aims was to investigate why temperatures above the Great Red Spot appear higher at the time, as revealed by recent observations by the NASA Infrared Telescope Facility. However, our new data showed a completely different result.”
The team hopes to gain a better understanding of this part of Jupiter’s atmosphere with further observations from JWST, which will also inform planned observations by the European Space Agency’s JUICE mission, which will investigate Jupiter and its three icy moons.
These results are Natural Astronomy.