NASA’s Juno spacecraft arrived in orbit of Jupiter last summer, and it began its death-defying dives into Jupiter’s magnetic field earlier this year. It’s on a longer 53-day orbit than originally planned due to engine trouble, but NASA is still gathering lots of information. NASA has just published the first data from Juno, and it reveals some fascinating things about Jupiter. For one, it has cyclones the size of a planet.
Juno is in a polar orbit, which allows it to see the entire surface of Jupiter, including the poles. That’s where Juno used its JunoCam imager to spot the massive cyclones that dominate the cloudscape (above). One of the storms was found overlapping the terminator, a line the separates the light side from the dark. That created shadows that were used to calculate the size of the storm. NASA says these cyclones stick up 30-60 miles above the cloud layer and are about half the diameter of Earth.
These cyclones are present at both poles, but the arrangement and size are different. Many of the storms even brush up against each other. They’re also nothing like the hexagonal storm on Saturn’s north pole. Scientists aren’t currently sure how these storms form, but that’s something Juno might find out as it continues the mission.
The other surprises are less visual, but perhaps more important to our understanding of Jupiter and other gas giants. Juno carries a Microwave Radiometer, which samples the thermal microwave radiation from Jupiter’s atmosphere. It can actually figure out what molecules are hidden deep under the top cloud layer, and Juno reports there’s a mysterious belt of ammonia down there around the equator.
Then there’s Jupiter’s incredibly strong magnetic field. NASA expected it to be strong, but not this strong. Juno’s magnetometer reads 7.766 Gauss, a whopping ten times more powerful than Earth’s magnetic field and twice what was as expected.
On Earth, the magnetic field is a product of the rotating metallic core, which is known as a dynamo. The closer you are to the dynamo, the more variable the field becomes. As Juno gets closer to Jupiter’s cloud layer, the field variance goes up—NASA describes it as “lumpy.” That, along with the high field strength, could indicate Jupiter’s core is not small and compact as previously thought. Jupiter’s core may not be one solid body.
More data from Juno is expected later this summer. With each pass, NASA gets a few more pieces of the puzzle. Hopefully we have the full picture when Juno deorbits in a few years.