Monstrous cyclones are churning over Jupiter's poles, until now a largely unexplored region that is more turbulent than scientists expected.

NASA's Juno spacecraft spotted the chaotic weather at the top and bottom of Jupiter once it began skimming the cloud tops last year, surprising researchers who assumed the giant gas planet would be relatively boring and uniform down low.

"What we're finding is anything but that is the truth. It's very different, very complex," Juno's chief scientist Scott Bolton of the Southwest Research Institute said Thursday.

With dozens of cyclones hundreds of miles across — alongside unidentifiable weather systems stretching thousands of miles — the poles look nothing like Jupiter's equatorial region, instantly recognizable by its stripes and Great Red Spot, a raging hurricane-like storm.

"That's the Jupiter we've all known and grown to love," Bolton said. "And when you look from the pole, it looks totally different ... I don't think anybody would have guessed this is Jupiter."

He calls these first major findings — published Thursday — "Earth-shattering. Or should I say, Jupiter-shattering."

Turning counter-clockwise in the northern hemisphere just like on Earth, the cyclones are clearly clustered near the poles. The diameters of some of these confirmed cyclones stretch up to 1,700 miles (2,800 kilometers). Even bigger, though shapeless weather systems are present in both polar regions. At the same time, the two poles don't really resemble each other, which is puzzling, according to Bolton.

Scientists are eager to see, over time, whether these super cyclones are stable or dynamic. "Are they going to stay the same way for years and years like the Great Red Spot ... Of course, only time will tell," Bolton said.

Just as intriguing will be how fast these super cyclones are moving.

Launched in 2011 and orbiting Jupiter since last summer, Juno is providing the best close-up views ever of our solar system's largest planet, peering beneath the clouds for a true portrait. It's made five close passes over Jupiter so far for science collection, the most recent last week; they occur about every two months given Juno's extremely oblong orbit. The next one will be in July, with investigators targeting the Great Red Spot.

Juno is moving so fast during these chummy encounters that it takes only two hours to get from the north pole to the south.

Besides polar cyclones, Juno has spotted white ice caps on Jupiter — frozen bits of ammonia and water. Bolton refers to them as Jovian snowfall — or maybe hail.

Juno also has detected an overwhelming abundance of ammonia deep down in Jupiter's atmosphere, and a surprisingly strong magnetic field in places — roughly 10 times greater than Earth's. It's also led scientists to believe Jupiter may have a "fuzzy" core — as Bolton puts it — big but partially dissolved.

Then there are the eerie sounds of plasma waves at Jupiter — "nature's music," according to Bolton. During the teleconference, he played two minutes of the spacecraft's recording from February, adjusted for the human ear and full of percussion sounds as well as high-pitched beeps and squeals, and even flute-like notes.

Results were published in Science and Geophysical Research Letters.

Jupiter's poles appear dramatically different from neighboring Saturn's, according to the scientists, with nothing like the hexagon-shaped cloud system over Saturn's north pole.

Researchers hope to compare Juno's observations with those of NASA's Cassini spacecraft, in its final months orbiting Saturn.

Juno's findings are "really going to force us to rethink not only how Jupiter works, but how do we explore Saturn, Uranus and Neptune," Bolton said.

Quelle: abc

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Nasa's Juno probe captures dramatic first close-up images of Jupiter

Excitement greets pictures of giant, chaotic weather systems plus new measurements that will help build unprecedented map of planet’s interior

 
 
Jupiter’s south pole, as seen by the 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 separate orbits were combined to show all areas in daylight, enhanced colour, and stereographic projection.
 Jupiter’s south pole, as seen by the 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. Photograph: NASA/JPL-Caltech/SwRI/MSSS/Betsy Asher Hall/Gervasio Robles

The first close-up observations from Nasa’s Juno spacecraft have captured towering clouds, swirling cyclones and dramatic flows of ammonia that drive giant weather systems on the largest planet in the solar system.

The $1.1bn probe swung into orbit around Jupiter in July last year on a mission to peer through the thick clouds that shroud the planet and learn how the alien world, and ultimately all of the planets in the solar system, formed around the nascent sun 4.5bn years ago.

“We were all jumping up and down with excitement when the images came down,” said Fran Bagenal, a planetary space physicist at the University of Colorado, who joined the Juno mission more than a decade ago. “You’ve got to be patient, but the rewards are fantastic.”

Once every 53 days the Juno spacecraft swings close to Jupiter, speeding over its clouds. In just two hours, the spacecraft travels from a perch over Jupiter’s north pole through its closest approach (perijove), then passes over the south pole on its way back out.
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 Once every 53 days the Juno spacecraft swings close to Jupiter, speeding over its clouds. In just two hours, the spacecraft travels from a perch over Jupiter’s north pole through its closest approach (perijove), then passes over the south pole on its way back out. Photograph: Credits: NASA/SWRI/MSSS/Gerald Eichstädt/Seán Doran

The spacecraft survived an almost six-year, 2.8bn km voyage across the depths of space to reach its destination, where it ducked beneath Jupiter’s intense radiation belts, turned on its suite of instruments, and swept into an orbit that loops over the planet’s north and south poles.

From 5,000km above the brown-orange blanket that covers the planet, Juno’s camera snapped pictures of tall, white storm clouds standing high above the rest. Some were so high, they stood out even on the nightside of the planet, betrayed by the feeble light of the sun glinting off them.

Yet more images revealed flashes of lightning that illuminate the Jovian sky. “The weather is dramatic,” said Bagenal. “What we thought we knew about Jupiter, we underestimated. It’s more variable, there are more features, there is much more detail the closer you look.”

Described as a “planet on steroids” by Scott Bolton, the mission’s principal investigator at the Southwest Research Institute in San Antonio, Jupiter is an enormous gas giant made from hydrogen and helium. Compared with Jupiter and the sun, the rest of the solar system is an afterthought. All of the other planets, the asteroids and comets, would fit within Jupiter, a planet 11 times wider than Earth.

Writing in two papers in the journal Science today, the Juno team describe fresh images and measurements of the planet’s atmosphere, magnetic field and the brilliant non-stop lightshows that constitute the aurorae at Jupiter’s poles.

An image of the North polar region of Jupiter.
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 An image of the North polar region of Jupiter. Photograph: MSSS/SwRI/JPL-Caltech/NASA

Its sensors peering down as it swooped around the planet, Juno spotted chaotic scenes with bright oval-shaped features swirling in the clouds. Time-lapse images revealed them to be enormous cyclones, rotating counter-clockwise in the northern hemisphere. The storms reached up to 1,400km wide, more than ten times the size of the largest cyclones on Earth. Deep inside the atmosphere, the scientists found evidence for what they called an “equatorial plume” – a massive and unexpected overturning of gas driven by a steady upward stream of ammonia from around the planet’s equator. It seems to mirror the Hadley cell convection currents on Earth, where warm air rises at the equator and falls again about 30 degrees to the north and south. But “It looks like a band that goes all the way round the middle of Jupiter,” said Bagenal. The question is where does it go down?”

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Another instrument on Juno measured the magnetic field of the planet and found it to be twice as strong as scientists expected, at about ten times greater than the field that surrounds Earth. During observations of the planet’s intense aurorae, Juno detected streams of electrons hurtling down into Jupiter’s upper atmosphere, where they potentially power the spectacular light shows.

Over the coming months, Juno will build up an unprecedented map of the planet’s interior before its instruments succumb to the harsh radiation and the spacecraft plunges into the clouds at the end of its mission. Along for the ride are three Lego crew members: the Roman god Jupiter, his wife Juno, and a telescope-wielding Galileo, who discovered four of Jupiter’s 53 moons.

One mystery scientists are keen to clear up is whether Jupiter has a solid core. With more data from the orbiting Juno, it is a puzzle they hope to answer. “We’re having to put together this 3D puzzle,” Bagenal said. “And surprise, surprise, it isn’t like Earth.”

Quelle: theguardian

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Update: 28.05.2017

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A WHOLE NEW JUPITER: FIRST SCIENCE RESULTS FROM NASA’S JUNO MISSION

 

Early science results from NASA’s Juno mission to Jupiter portray the largest planet in our solar system as a complex, gigantic, turbulent world.
Credit: NASA/JPL-CalTech/USGS.

WASHINGTON, DC — Early science results from NASA’s Juno mission to Jupiter portray the largest planet in our solar system as a complex, gigantic, turbulent world, with Earth-sized polar cyclones, plunging storm systems that travel deep into the heart of the gas giant, and a mammoth, lumpy magnetic field that may indicate it was generated closer to the planet’s surface than previously thought.

“We are excited to share these early discoveries, which help us better understand what makes Jupiter so fascinating,” said Diane Brown, Juno program executive at NASA Headquarters in Washington, D.C. “It was a long trip to get to Jupiter, but these first results already demonstrate it was well worth the journey.”

Juno launched on Aug. 5, 2011, entering Jupiter’s orbit on July 4, 2016. The findings from the first data-collection pass, which flew within about 2,600 miles (4,200 kilometers) of Jupiter’s swirling cloud tops on Aug. 27, are being published this week in two papers in the journal Science, as well as a 44-paper special collection in Geophysical Research Letters, a journal of the American Geophysical Union.

“We knew, going in, that Jupiter would throw us some curves,” said Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio. “But now that we are here we are finding that Jupiter can throw the heat, as well as knuckleballs and sliders. There is so much going on here that we didn’t expect that we have had to take a step back and begin to rethink of this as a whole new Jupiter.”

Among the findings that challenge assumptions are those provided by Juno’s imager, JunoCam. The images show both of Jupiter’s poles are covered in Earth-sized swirling storms that are densely clustered and rubbing together.

“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,” said Bolton. “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?”

Another surprise comes from Juno’s Microwave Radiometer (MWR), which samples the thermal microwave radiation from Jupiter’s atmosphere, from the top of the ammonia clouds to deep within its atmosphere. The MWR data indicates that Jupiter’s iconic belts and zones are mysterious, with the belt near the equator penetrating all the way down, while the belts and zones at other latitudes seem to evolve to other structures. The data suggest the ammonia is quite variable and co

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