Caption: This picture of the Jupiter's South Pole is a mosaic of many images acquired by the Jovian InfraRed Auroral Mapper at wavelengths around 5 µm during perijove pass #4. The images have been taken in different times while Juno was leaving the planet after the closest approach. What you see here is the heat (measured as radiance) coming out from the planet through the clouds: yellow indicates the presence of thinner clouds and dark red the thicker ones.  Credit: NASA/SWRI/JPL/ASI/INAF/IAPS

EXPERT REACTION: Jupiter spills his heavy secrets to spacecraft wife Juno

Embargoed until: Publicly released:

Jupiter’s deep interior is made up of a fluid mixture of hydrogen and helium rotating as a solid body, according to a collection of papers based on data gathered by NASA's Juno spacecraft, named after the gas giant's mythological wife. The international researchers also found eight cyclones rotating around a single cyclone at the north pole, and the south polar cyclone circled by five cyclones. An accompanying editorial says more information about Jupiter and Saturn's interiors could help us understand gas giants.

Journal/conference: Nature

Organisation/s: Sapienza Università di Roma, Italy | Weizmann Institute of Science, Israel | Université Côte d’Azu, France | INAF-Istituto di Astrofisica e Planetologia Spaziali, Italy

Media Release

From: Springer Nature

Detailed insights into the properties of Jupiter, including its gravitational field, its atmospheric flows, its interior composition and its polar cyclones, are reported in four papers published in this week’s Nature. The studies present some of the key findings of NASA’s Juno mission to the gas giant. Despite extensive studies of Jupiter’s surface, with its distinctive dark ‘bands’ and bright ‘zones’, the planet’s deep interior has remained poorly understood.

Luciano Iess and colleagues used Doppler data based upon the Juno spacecraft’s motion to study Jupiter’s gravitational field, which is known to vary from pole to pole. The authors show that this north‒south asymmetry, which is unexpected for a fluid planet that is fast-rotating and oblate (squashed at the poles), results from atmospheric and interior wind flows. Two further studies assess the depths of these flows. Yohai Kaspi and colleagues analyse Jupiter’s ‘odd’ gravity moments, and show that its jet streams extend to 3,000 kilometres below cloud level. They also report that Jupiter’s turbulent atmosphere involves about 1 per cent of the planet’s total mass. From their analysis of the ‘even’ gravity moments, Tristan Guillot and co-authors find that at depths greater than 3,000 kilometres below cloud level, Jupiter’s deep interior is made up of a fluid mixture of hydrogen and helium, rotating as a solid body.

In a fourth paper, Alberto Adriani and colleagues report comprehensive visible and infrared observations made by Juno of Jupiter’s polar regions. They find that the cyclones known to exist at Jupiter’s poles create persistent polygonal patterns. At the north pole, eight circumpolar cyclones rotate around a single cyclone, whereas the south polar cyclone is circled by five such cyclones. The origins of these cyclones and how they persist without merging remain unknown, however.

Writing in an accompanying News & Views article, Jonathan Fortney concludes that if a consistent physical picture can be put together for the interior dynamics of Saturn as well as Jupiter, it would go a long way towards solidifying our understanding of the internal dynamics of this class of gas giant planets.


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    Paper 3 - The URL will go live after the embargo ends
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    Paper 4 - The URL will go live after the embargo ends

Expert Reaction

These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.

Emeritus Professor Andrew Prentice is an Affiliate Scientist in the School of Physics & Astronomy at Monash University

In July 2016, NASA’s $1.1bn Juno spacecraft attempted to become the second-ever spacecraft to go into orbit about Jupiter.

In doing so, it experienced a major hardware glitch, as had happened to its predecessor, the Galileo Orbiter, in 1995. In Juno’s case it was not an antenna that became stuck but to two sticking valves that stopped the firing of jets, thus preventing the spacecraft from descending to its planned 14-day circular orbit, close to Jupiter’s cloud tops.

So, although Juno now has to make the best of an unplanned long and loopy 53-day orbit, the first batch of scientific measurements have been made and some very startling results discovered.

Jupiter’s gravity field is not symmetrical between the north and south hemispheres. In a series of four papers in Nature, Luciano Less and his co-workers - including many seasoned stalwarts from the heady Voyager 1 & 2 spacecraft days, Galileo and even Pioneer 10 (1973) - have concluded that this asymmetry could be due to sharp changes in the dynamic structure of the powerful winds and jet streams that patrol the outer 3000 km of Jupiter’s deep massive atmosphere.

Below this outer dynamic ‘skin’, which makes up just 1 per cent of Jupiter’s mass, the inner 99 per cent of Jupiter’s mass rotates smoothly and steadily, just like a rigid body. Thus deep down, despite the unfriendly greeting that he gave to Galileo and then Juno on their arrival, Jupiter really means no harm. He’s really like the line of the lyric “Ol’ man River, he jest keeps rollin along’."

Last updated: 07 Mar 2018 4:35pm
Dr. Rebecca Allen is from the Centre for Astrophysics and Supercomputing at Swinburne University of Technology

We have long known that Jupiter was this massive gas giant, but only now can we appreciate how those gases flow, interact, and shape the very gravity of the planet.

The Juno spacecraft has revealed that Jupiter’s gravity changes as you move from its north to south pole, and that this is driven by enormous flows of gas that extend thousands of kilometres below the planet’s surface.

Juno also uncovered vast systems of cyclones at Jupiter’s poles that defy logic. As we come closer to understanding the physics of this gas giant, we also realise there is more to learn!

Last updated: 07 Mar 2018 10:38am
Swinburne University’s A/Prof Alan Duffy, Lead Scientist of The Royal Institution of Australia

Deep beneath the clouds Jupiter has long hidden its secret inner structure from view. The exquisitely precise motion of the Juno satellite around the Gas Giant betrays the unexpected pull by the gravity of the clouds beneath. As the spacecraft orbits it builds up a map of regions that pull more strongly than others. The data can then be split into spherical harmonics or moments, similar to the notes on a drum, that trace out the scale and type of the gravitating structure beneath.

Our ears can tell a similar story when we hear the difference between striking a small tuning fork which gives a clear high-pitched ringing, and a large metal bar when struck that gives a dull, low-pitched sound.

The gravitational maps reveal enormous jet streams extending thousands of kilometre deep, until merging with a fuzzy interior. This interior has now been revealed to be a mixture of hydrogen and helium that rotates together as a solid body, similar to the Earth but, unlike our rocky solid surface, it is in fact a liquid.

The coloured surface indicates belts of cloud, Juno has revealed that these belts or zones make sudden jumps in direction, moving at hundreds of km/h either with or against Jupiter’s rotation, depending on what latitude you choose. If we had these on Earth, planes could use them like conveyor belts to easily move back and forth across the planet.

Finally, at the poles the planet is just plain nuts. The belts of cloud give way to continent sized cyclones that form polygonal shapes, either a pentagon with five points or octagon with eight, around each other. Why these cyclones haven’t merged together is a mystery; the only other example we have is Saturn which has only a single giant cyclone. They also appear to be fixed in place, when we would expect them to slowly rotate around. These raging tempests are as beautiful as they are mysterious.

Last updated: 07 Mar 2018 10:34am
Dr Brad Tucker is a Research Fellow and Outreach Manager at Mt. Stromlo Observatory at the Australian National University

Jupiter has fascinated astronomers and scientists alike for centuries. Moreover, over the past two decades of looking for other planets around other stars, many show similar sizes to that of Jupiter.

By understanding Jupiter, it will provide a window into many other exoplanets and solar systems.

These four papers show that there is more than meets the eye with Jupiter.

Underneath the cloudy surface is a core that moves like a liquid but acts like a solid. The storm systems at the north and south poles and the varying gravity across the planet show that Jupiter is a complex world.

More than just getting a better picture of Jupiter, this will help us in understand the moons of Jupiter, some of which may host life.

Last updated: 07 Mar 2018 10:27am

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