NASA in a media teleconference has recently released the first in-depth science results from the Juno mission at Jupiter. The Solar System’s largest planet is incredibly active and complex, with polar cyclone storm systems as large as Earth, other storms which plunge deep down into the atmosphere and an immense, but lumpy, magnetic field. Juno has sent back the most detailed images ever taken of the planet, showing the atmospheric storms and other features, including Jupiter’s rings, as never before.
The most obvious features are of course the planet’s belts of clouds with many circular storm systems, including the Great Red Spot. Even small telescopes can see some of these details. But now with Juno, we can see just how complex Jupiter’s atmosphere is, such as at the poles; previous spacecraft had glimpsed the poles before, but due to being in a polar orbit, Juno has provided the first detailed look at them, and they are incredible. While Jupiter’s equatorial regions are dominated by bands of clouds, the poles are covered in many cyclone-type storms each as large as the Earth. They are densely clustered and often rub against each other. Other data from Juno shows that the equatorial belts and zones are also perplexing – the belt closest to the equator penetrates very deep down into the atmosphere, while other belts apparently evolve into different structures farther down. These measurements come from Juno’s Microwave Radiometer (MWR), which samples the thermal microwave radiation from Jupiter’s atmosphere, from the top of the ammonia clouds to deep down in the atmosphere.
It should be remembered that Jupiter has no solid surface as such below the clouds, the atmosphere just keeps getting progressively denser until you reach the core. Previous models of Jupiter’s interior had been based only on gravitational measurements of the planet, but the new findings are providing a lot more detail. It also seems that Jupiter’s interior is not as uniform as once thought. Instead of a solid core, the data now suggests that Jupiter has a more “fuzzy” core, which is dilutely mingled with the overlying metallic hydrogen layer. Jupiter also has a very strong magnetic field, the most intense in the Solar System. Now we know it is even stronger than first thought, thanks to Juno. It is also more irregular or “lumpy.” Juno’s magnetometer investigation (MAG) found that the magnetic field is as strong as 7.766 Gauss, which is about 10 times stronger than the most powerful magnetic field on Earth. Along with the powerful magnetic field, Jupiter has incredible aurora displays at its poles – again more intense than those on Earth, and they also seem to behave differently than auroras on Earth.
Some of these new results had also been discussed almost a month ago at the European Geosciences meeting, but the new NASA briefing presented the latest information available with additional images. Juno orbits Jupiter every 53 days, soaring over the planet’s poles, allowing the spacecraft to get views never possible before. One of the new images also shows Jupiter’s main ring, from the inside looking out, something not possible before. It is reminiscent of Cassini’s latest views of Saturn’s rings from between the planet and the rings. It has been known for a long time that Jupiter has rings, they just are not nearly as prominent as Saturn’s. Juno just completed its sixth close flyby of Jupiter, during which some of the most amazing images were taken so far. The JunoCam is a public outreach camera, and a lot of fantastic image processing has been done by people not part of the mission team, such as Seán Doran. The images are breathtaking and show Jupiter in a way never seen before. Even tiny white clouds can be seen floating above the main storms and cloud belts.
The mission has been almost flawless so far, although a problem with the engine caused the mission team to announce that it would stay in the orbit for the rest of the mission, instead of moving in to a closer orbit as planned. Fortunately, that does not affect the science too much, and in some ways actually helps it. It also means that Juno will experience less intense radiation from Jupiter. Juno is not only rewriting the textbooks about Jupiter, it is also helping scientists to understand how gas giants in general form and evolve, including, perhaps, Jupitertype, and larger, exoplanets in other Solar Systems as well.