Juno mission first results: Jupiter isn’t like what researchers expected

Beneath its heavy cloud cover, Jupiter has been able to keep its secrets from astronomers. Now, first results from NASA’s Juno mission are challenging researchers’ beliefs about the gas giant.

The results were revealed during a media teleconference Thursday with NASA researchers and published in corresponding studies through the journal Science and Geophysical Research Letters.

Juno launched in August 2011 but didn’t arrive at Jupiter until July. The craft has been orbiting the planet and performing calculated flybys over the clouds. These happen every 53 days as Juno “screams by” Jupiter, going from the north to south pole in about two hours.

“The general theme of our discoveries is really how different Jupiter looked from how we expected,” said Scott Bolton, Juno principal investigator, from the Southwest Research Institute in San Antonio. “This is a close-up and personal look at Jupiter. We thought it was uniform inside and relatively boring. What we’re finding is anything but that. It’s very complex. Jupiter from the poles doesn’t look anything like it does from our usual view.”

In this image captured on December 30, 2020, Juno spotted lightning striking near Jupiter's north pole.

Jupiter's northernmost cyclone, seen to the right along the bottom edge of image, was captured by Juno.

This jack-o-lantern-esque view of Jupiter is a mosaic of images taken by the Gemini North telescope in Hawaii. The bright spots represent Jupiter's internal heat escaping through holes in the planet's massive cloud cover.

Part of Jupiter's southern equatorial region can be seen in this image captured by Juno's JunoCam imager. But it's flipped to show the expanse of Jupiter's atmosphere, with the poles to the left and right, rather than top to bottom.

In this image captured by Juno, six cyclones remain stable at Jupiter's south pole. A small cyclone, seen at the bottom right in yellow, has recently joined the party.

An artist's impression of a collision between a young Jupiter and a massive, still-forming protoplanet in the early solar system.

These dramatic swirls on Jupiter are atmospheric features. Clouds swirl around a circular feature in a jet stream region.

Is that a dolphin on Jupiter? No, but it definitely looks like one. It's actually a cloud that looks like it's swimming through cloud bands along the South Temperate Belt.

This composite image, derived from data collected by the Jovian Infrared Auroral Mapper (JIRAM) instrument aboard NASA's Juno mission to Jupiter, shows the central cyclone at the planet's north pole and the eight cyclones that encircle it.

This striking image of Jupiter was captured by NASA's Juno spacecraft as it performed its eighth flyby of the gas giant.

Algorithmic-based scaling and coloring reveal a vivid look at the Great Red Spot in July 2017.

Jupiter's Great Red Spot is a storm with a 10,000-mile-wide cluster of clouds in July 2017.

Color enhancements offer a detailed look into the Great Red Spot.

NASA configured this comparison of its own image of Earth with an image of Jupiter taken by astronomer Christopher Go.

This artist's concept shows the pole-to-pole orbits of the NASA's Juno spacecraft at Jupiter.

This image shows Jupiter's south pole, as seen by NASA's Juno spacecraft from an altitude of 32,000 miles (52,000 kilometers). The oval features are cyclones, up to 600 miles (1,000 kilometers) in diameter. Multiple images taken with the JunoCam instrument on three orbits were combined to show all areas in daylight, enhanced color and stereographic projection.

An even closer view of Jupiter's clouds obtained by NASA's Juno spacecraft.

Jupiter's north polar region comes into view as NASA's Juno spacecraft approaches the giant planet. This view of Jupiter was taken when Juno was 437,000 miles (703,000 kilometers) away during its first of 36 orbital flybys of the planet.

This infrared image gives an unprecedented view of the southern aurora of Jupiter, as captured by NASA's Juno spacecraft on August 27, 2016. Juno's unique polar orbit provides the first opportunity to observe this region of the gas-giant planet in detail.

NASA's Juno spacecraft has sent back its first photo of Jupiter, left, since entering into orbit around the planet. The photo is made from some of the first images taken by JunoCam and shows three of the massive planet's four largest moons: from left, Io, Europa and Ganymede.

An illustration depicts NASA's Juno spacecraft entering Jupiter's orbit. Juno will study Jupiter from a polar orbit, coming about 3,000 miles (5,000 kilometers) from the cloud tops of the gas giant.

This was the final view of Jupiter taken by Juno before the on-board instruments were powered down to prepare for orbit. The image was taken June 29, 2016, while the spacecraft was 3.3 million miles (5.3 million kilometers) from Jupiter.

NASA's Hubble Space Telescope captured images of Jupiter's auroras on the poles of the gas giant. The observations were supported by measurements taken by Juno.

This artist rendering shows Juno orbiting Jupiter.

Jupiter and the gaseous planet's four largest moons -- Io, Europa, Ganymede and Callisto -- are seen in a photo taken by Juno on June 21, 2016. The spacecraft was 6.8 million miles (10.9 million kilometers) from the planet.

Juno made a flyby of Earth in October 2014. This trio of images was taken by the spacecraft's JunoCam.

Three Lego figurines are flying aboard the Juno spacecraft. They represent the Roman god Jupiter; his wife, Juno; and Galileo Galilei, the scientist who discovered Jupiter's four largest moons on January 7, 1610.

Jupiter was 445 million miles (716 million kilometers) from Earth when Juno was launched from Cape Canaveral, Florida, on August 5, 2011. But the probe traveled a total distance of 1,740 million miles (2,800 million kilometers) to reach Jupiter, making a flyby of Earth to help pick up speed.

Technicians use a crane to lower Juno onto a stand where the spacecraft was loaded with fuel for its mission.

Technicians test the three massive solar arrays that power the Juno spacecraft. In this photo taken February 2, 2011, each solar array is unfurled at a Lockheed Martin Space Systems facility in Denver.

Juno, meet Jupiter

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During the flybys, observations and data showed Jupiter’s previously unseen poles. Bright ovals at the poles were revealed to be gigantic cyclones spanning 870 miles. Juno was also able to probe the cloud cover and discover wells of ammonia that form giant and violent weather systems in the deep atmosphere.

But this ammonia isn’t consistently mixed, like researchers believed. The variation shifts from high to low.

In the cut-out image to the right, orange signifies high ammonia abundance, and blue signifies low ammonia abundance. Jupiter appears to have a band around its equator high in ammonia abundance.

The giant cyclones at the poles are also new to researchers. Further study could reveal whether these are like the Great Red Spot, which has been observable for at least 300 years, or more ephemeral.

“We’re puzzled as to how they could be formed, how stable the configuration is and why Jupiter’s north pole doesn’t look like the south pole,” Bolton said. “We’re questioning whether this is a dynamic system, and are we seeing just one stage, and over the next year, we’re going to watch it disappear, or is this a stable configuration and these storms are circulating around one another?”

This image of Jupiter is a composite of four images taken by NASA's Cassini spacecraft in December, 2000. The images were combined to illustrate what Jupiter would look like if the cameras on Cassini had captured the entire planet. Jupiter's moon Europa is casting the dark shadow on the planet.

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Imaging also revealed intriguing cloud features.

“The idea of seeing those little cloud features full of ammonia and water ice, it’s like it’s snowing on Jupiter and we’re seeing how it works,” Bolton said. Or it could be hail, he said.

A close-up of the bright clouds that dot Jupiter's south tropical zone, as seen by NASA's Juno spacecraft.

Juno revealed that Jupiter’s magnetic field is 10 times stronger than the strongest magnetic field on Earth and and twice as strong as anticipated, exceeding researchers’ expectations. The mission had an encounter with the planet’s “bow shock,” akin to a type of stationary shockwave, when exploring Jupiter’s magnetosphere.

The researchers compared this bow shock to a Hadley cell on Earth, without the rain. A Hadley cell is the atmospheric circulation of air rising near the equator that creates hurricanes, jet streams, trade winds and rain belts.

“Juno is giving us a view of the magnetic field close to Jupiter that we’ve never had before,” said Jack Connerney, Juno deputy principal investigator. “Already, we see that the magnetic field looks lumpy: It is stronger in some places and weaker in others. This uneven distribution suggests that the field might be generated by dynamo action closer to the surface, above the layer of metallic hydrogen. Every flyby we execute gets us closer to determining where and how Jupiter’s dynamo works.”

Voyager 1 at Jupiter - Red spot Image taken on March 5, 1979 This image was re-processed on November 6, 1998 and re-recorded to film on the MDA film recorder, MRPS ID# 93779, from which this file was scanned. Original vidicon image size is 800 lines with 800 pixels per line.

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Juno also encountered Jupiter’s huge auroras, captured in ultraviolet and infrared images, and the electron beam pushing energy into the planet’s upper atmosphere, which could be creating the auroras.

A still from the animation of Jupiter's southern lights.

And Juno was able to measure Jupiter’s gravitational field. Those data, combined with information to be gathered as Juno’s mission continues, can help researchers determine the structure of Jupiter’s atmosphere and answer the big question: Does the planet have a solid core?

Previous models have suggested this, but Juno’s unique data could provide actual insight. If the planet has a solid core, it could change the belief that the gas giant is largely composed of hydrogen and helium.

Juno's gravity field data will reveal new clues about Jupiter's core.

Luckily, Juno is just getting started.

Even though Jupiter is the largest planet in our solar system, astronomers don’t know much about its origin. The Juno mission was designed to collect data and observations that will reveal the origin and evolution of the gas giant. Its other objectives include mapping Jupiter’s gravitational and magnetic fields, observing auroras, measuring the amount of water and ammonia in its atmosphere and finding evidence of a solid core.

This sequence of enhanced-color images shows how quickly the viewing geometry changes for NASA's Juno spacecraft as it swoops by Jupiter. T

The planet’s cloudy atmosphere has contributed greatly to obscuring general knowledge. Juno was designed to look below those clouds at the planet underneath. This will also help astronomers determine finer points about Jupiter’s composition and how much of it is water.

Europa Enceladus

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Jupiter was most likely the first planet to form in the solar system and contains some of the same ingredients of the collapsing nebula that formed the system. Knowing more about Jupiter can provide greater insight about its beginnings.

Given the fact that gas giants are common around other stars, this could inform future observations of exoplanets and other planetary systems.

The next flyby will happen July 11 and go directly over the Great Red Spot.

“If anybody is going to get to the bottom of what is going on below those mammoth swirling crimson cloud tops, it’s Juno and her cloud-piercing science instruments,” Bolton said.