The swirls and vortexes in the clouds of gas giants like Jupiter sometimes have analogs in Earth’s atmosphere, but some cloud formations are completely alien. NASA’s Juno probe has been in orbit of Jupiter since 2016, sending back fascinating images and data from the solar system’s largest planet. In the latest set of discoveries, Juno reveals the wild octagonal storm at Jupiter’s north pole and the depth of the planet’s iconic stripes.
We’ve come to expect complex vortices in the polar region of large gas giants. For example, Saturn has a hexagonal cloud formation on its north pole. As you can see in the image above, Jupiter’s north pole is pretty surprising even in the context of other gas giants.
Scientists had expected something Saturn-like — a six or eight-sided vortex. Instead, they got eight storms around a large central one. The south pole is similar, but has just six cyclones surrounding the main storm. Juno scanned the poles with its Jovian Infrared Auroral Mapper (JIRAM) instrument, so this isn’t a natural color image. NASA says the wind gusts as high as 220 miles per hour (350 kilometers per hour) in the vortexes, and each of them is several thousand miles across.
We were unable to see Jupiter’s polar storms from Earth because of Jupiter’s low axial tilt. Past missions to Jupiter didn’t enter a polar orbit, which is necessary to map a planet’s entire surface. Juno is in such an orbit, completing one loop every 53 days. This gives it a unique overview of the planet’s wind patterns, and scientists used that the measure how deep the surface features go. It turns out, probably deeper than you thought.
Jupiter’s gravity affects the radio signal from Juno, and gravity is not uniform across the planet because the striped clouds have varying mass. Because Juno is in a polar orbit, it passes over a different part of the planet each time. Thus, the radio distortion reveals a map of Jupiter’s gravity and can tell us about the nature of the stripes below the surface.
According to NASA’s analysis of Jupiter’s gravity, those cloud bands extend about 1,800 miles (3,000 kilometers) below the surface. That’s much deeper than previously thought. Related research also indicates that Jupiter’s interior moves as a single body. That could explain why its appearance has been so consistent over the centuries. Galileo observed the planet’s stripes in the early 17th century.
Juno will no doubt provide many more insights into Jupiter during its mission. The probe will continue in its current orbit through this summer, at which time NASA will likely seek to extend its mission.
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