spaceSpace and Physics

Juno Reveals Breathtaking New Views Of Jupiter's North Pole And Its Mysterious Dynamo


Robin Andrews

Science & Policy Writer

Cyclones and anticyclones dance about each other in Jupiter's northern polar region. NASA via YouTube

NASA’s Juno mission is the gift that keeps on giving. From peering into Jupiter’s atmosphere to probing its gravitational well, it’s lifting the lid on longstanding mysteries that scientists have struggled to answer. To wit, a pair of beautiful videos showcasing Juno’s research on these exact phenomena have just made their debut.

The first is a 3D flyover of Jupiter’s northern polar region, as viewed through an infrared filter. The images were taken by the Jovian InfraRed Auroral Mapper (JIRAM) instrument, whose ability to spot meteorological marvels through tens of kilometers of hazy clouds has highlighted a number of curious features.


By far the most stunning is a strange form of synchronized dancing taking place up there: one massive cyclone is surrounded by eight other circumpolar cyclones. Individual diameters vary, but at least one is 4,600 kilometers (2,900 miles) across – roughly the same distance you’d take traveling from New York to San Francisco.

These images, taken during the spacecraft’s fourth pass, also reveal that the temperatures of the cyclones are far chillier than our terrestrial equivalents. The maximum temperature of those featured in the video appears to be around -13°C (8.6°F), with the coolest points higher up in the atmosphere and along the “limbs” of the cyclones registering as low as -83°C (-117°F).


The second newly unleashed video, however, is arguably the more fascinating. Using eight orbits of Jupiter, researchers have managed to produce a model of how Jupiter’s internal dynamo works, and thus gain an insight into how its magnetic field works.


Earth’s magnetic field, although still fairly mysterious in some respects, is far better understood. Earth has a liquid, iron-rich outer core; as it cools, its contents move around in convection currents and, thanks to a quirk of physics known as the dynamo theory, this generates a life-protecting, aurora-influencing magnetic field.

Jupiter also has a magnetic field, but it is truly enormous, by far the largest in the Solar System. Without knowing what its innards are doing, however, how it produces such a colossus remained highly speculative.

Thanks to Juno’s ability to probe internal gravity changes as things move about, however, we now have, for the first time, a working observational model of the gas giant’s own dynamo. It’s safe to say that it surprised those looking through the data, and other researchers who’ve spent much of their careers trying to guess what it may be like.

“We’re finding that Jupiter’s magnetic field is unlike anything previously imagined,” the mission’s deputy-principal investigator, Jack Connerney of the Space Research Corporation, said in a statement.


Instead of being a “simple” bar magnet model that more or less applies to our own world, it turns out that Jupiter’s is both messy and far more complex.


Between the north pole and the equator, for example, an intense spot of positive magnetic field is surrounded by areas that are far weaker and negative. The south pole, however, is intensely negative, and it progressively weakens as you get nearer to the equator.

So – what’s causing this anomalous behavior? At present, rather marvelously, no-one’s quite sure, although it’s indubitably something happening deep below that we’ve yet to see in its still-enigmatic interior.


Hopefully, Juno’s additional orbits will take us some way toward solving this increasingly bemusing dilemma.


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