Nasa's Juno reveals Jupiter's interior in unprecedented detail

Juno orbiting Jupiter providing unparalleled insight into the giant planet

Image of cyclone at Jupiter's north pole. Jupiter's wind flows actually extend 3,000 kilometers (about 1,860 miles) below the cloud tops, where the pressure is about 100,000 times that of the atmosphere at Earth's surface.

Juno data has indicated that the weather layer of Jupiter is more massive and extended much deeper into the planet than previously expected.

The recent things uncovered are part of a four-article collection on Juno science results published in the journal Nature. The most famous feature of Jupiter is the Great Red Spot, but also noteworthy are the bands of light and dark clouds that make up what we can see of the planet from afar.

To see beneath Jupiter's veil of clouds and study its winds, the Juno team precisely measured the planet's gravitational field.

The findings will improve understanding of Jupiter's interior structure, core mass and, eventually, its origin, NASA said. There has been disagreement over whether the planet's bands are a weather system, comparable to the Earth's jet streams, or whether they are an aspect of a deeper-seated convection system that transports energy out of the interior. Now we know that those jet streams are very deep, we also know that the gravity variation is much greater than we previously expected.

But underneath, the planet's liquid core of hydrogen and helium rotates uniformly, behaving nearly like a solid body, researchers found.

"This is really an wonderful result, and future measurements by Juno will help us understand how the transition works between the weather layer and the rigid body below", said lead author of the paper on Jupiter's deep interior, Tristan Guillot. The large central cyclone is surrounded by eight other cyclones and are said to be like nothing else discovered in our solar system.

Juno launched in 2011 with the ambitious mission of finally seeing beneath the dense clouds covering Jupiter. Like in the North, Jupiter's south pole also contains a central cyclone, but it is surrounded by five cyclones with diameters ranging from 3,500 to 4,300 miles (5,600 to 7,000 km) in diameter. "We tried to fit the Cassini data in the same way as Juno's data, but simply it did not work". A similar situation may be occurring at other big gas planets like Saturn, where the atmosphere could be even deeper than Jupiter's, he said.

"They have very violent winds, reaching, in some cases, speeds as great as 220 miles per hour (350 kph)".

These new insights will go a long way towards building a better understanding of gas giant planets, including those in distant solar systems.

How these structures formed and how they continue to survive without merging are still open questions.

Of course, the total observation period of Jupiter's poles only spans about seven months, so it's certainly possible the cyclone pattern could change in the future, hopefully while Juno is able to capture it.

Fortunately, Juno will remain in orbit for at least a couple of years, so we'll certainly have more to learn about Jupiter. Juno carries no instrument capable of directly measuring such asymmetries, but they should manifest as subtle alterations in the spacecraft's motion as it moves through its 53-day polar orbit around the planet. The Italian Space Agency (ASI), contributed two instruments, a Ka-band frequency translator (KaT) and the Jovian Infrared Auroral Mapper (JIRAM).

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