We Now Know What Lies Beneath Jupiter's Clouds

Juno orbiting Jupiter providing unparalleled insight into the giant planet

Juno orbiting Jupiter providing unparalleled insight into the giant planet. Erik Simonsen Getty Images

Jupiter's beauty is more than skin deep.

Jupiter is a type of planet called a gas giant, as opposed to rocky planets like Earth and Mars, and its composition is 99 per cent hydrogen and helium.

Previous studies of Jupiter focused on the planet's most obvious features - its dark bands, bright zones, and big red spot - but these four studies use small signatures from the gas giant's gravitational field to dig much deeper. These clouds and winds are thought to be as old as the planet itself, but until now we haven't been able to tell what exactly lies beneath these bands that have obscured our vision of the surface for so long.

But what if we went even deeper than those 3,000 kilometres below cloud level? No one knew for sure-until now.

"Juno's discovery has implications for other worlds in our solar system and beyond", he said.

They determined that the magnitude of the winds of Jupiter decayed with altitude, finally petering out at a depth of around 3,000 kilometres (1,864 miles) below cloud level. In comparison, the Earth's atmosphere is less than one millionth of our planet's mass. These charged particles drag against Jupiter's powerful magnetic field, dampening the winds.

Since the famous stripes of the planet Jupiter were seen by Galileo in the early 17th century, scientists have wondered whether they are just colorful bands or a significant layer of the planet. Essentially, the resulting force of Jupiter's rotation around its axis should produce a perfectly symmetric "bulge" around the equator. Any asymmetry would be an unmistakable sign of complex internal structures, such as large flows of material deep in the planet's atmosphere. Juno swings around the planet on an elliptical orbit about once every 53.5 days.

Using a large antenna from NASA's Deep Space Network of radio telescopes tuned in to a special transponder on Juno provided by the Italian Space Agency, the team repeatedly searched for any unexplained anomalies in the spacecraft's trajectory. Luciano Iess of Sapienza University of Rome, presents the findings of asymmetry in the gravitational fields.

The wind belts that encircle the planet, explained Kaspi, are much stronger than the fiercest winds on Earth and have lasted for at least hundreds of years.

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For the past year and a half, the NASA spacecraft Juno has been circling Jupiter and collecting data from the turbulent planet. An independent analysis by William Folkner and colleagues at the NASA Jet Propulsion Laboratory verified the hard measurement. They also suggest the electrical conductivity of a gas-giant planet's atmosphere is the crucial property that sets the limits for such a world's dynamic winds, as ionized gases at high pressures drag against its magnetic field.

New findings from NASA's Juno spacecraft show Jupiter's weather systems extend much deeper than previously believed and that the huge planet rotates almost as a rigid body below the racing jet streams, storms and cyclones.

Remarkably, these predictions are already being tested. By measuring the difference in frequencies between transmitted and received signals, Iess was able to infer minute changes in the probe's speed, caused by variation in Jupiter's gravitational field.

Saturn, Jupiter's gaseous neighbor, has only single cyclonic systems at each pole. Juno will continue to gather data until July 2018. "The picture that is emerging from Cassini is that of a planet very different from Jupiter".

"The result is a surprise because this indicates that the atmosphere of Jupiter is massive and extends much deeper than we previously expected", Kaspi said in an email. The pair and their collaborators have reportedly submitted a paper detailing the findings to the journal Science. NASA might choose to extend it, but the spacecraft could still succumb any day to the intense radiation from the deadly halos of high-energy particles trapped around the planet by magnetic fields.

An artist's conception of the Juno spacecraft in orbit around Jupiter.

The first of the three Nature papers, led by Prof.

Researchers poring over these datasets are finally uncovering some of the planet's mysteries.

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