Juno sees mega-waves on Jupiter
NASA craft confirms Voyager observation from 40 years ago. Lauren Fuge reports.
NASA’s Juno spacecraft has confirmed the existence of massive, wave-like structures on the surface of Jupiter.
Called atmospheric wave trains, these towering structures of moving air were first discovered when NASA’s Voyager missions sling-shotted around the gas giant in 1979. The waves follow one another in successive crests and troughs as they hurtle around the planet, with most moving in an east-west direction.
Juno’s visible-light JunoCam imager – the spacecraft’s “eye” – has now resolved smaller distances than ever before between each individual wave, providing valuable insights into the atmosphere’s dynamics and structure.
“JunoCam has counted more distinct wave trains than any other spacecraft mission since Voyager,” says Glenn Orton, from NASA’s Jet Propulsion Laboratory in Pasadena, California.
“The trains, which consist of as few as two waves and as many as several dozen, can have a distance between crests as small as about 65 kilometres and as large as about 1200 kilometres.”
One wave was estimated to be 10 kilometres tall – a little less than the cruising altitude of commercial jets on Earth.
“The waves can appear close to other Jovian atmospheric features, near vortices or along flow lines, and others exhibit no relationship with anything nearby,” explains Orton.
“Some wave trains appear as if they are converging, and others appear to be overlapping, possibly at two different atmospheric levels. In one case, wave fronts appear to be radiating outward from the centre of a cyclone.”
So, what causes these peculiar structures?
Scientists think most of them are atmospheric gravity waves. Unrelated to gravitational waves in spacetime, gravity waves can occur in air or liquid and are created when gravity attempts to restore equilibrium. (Think of wind-driven waves at the ocean surface.)
On Jupiter, these waves are vertical ripples in the upper atmosphere, caused by disturbances below, such as thunderstorm updrafts or wind flowing over surface features.
This observation is just one piece of the puzzle of Jupiter’s atmosphere. Indeed, one of Juno’s ongoing goals is to learn more about what goes on beneath the planet’s thick, swirling clouds. Since sliding into orbit in 2016, the spacecraft has made a variety of discoveries about Jupiter’s interior composition, atmospheric flows, stormy bands, extreme weather and more.