November 29, 2021 Juno photographs two storms on Jupiter
Image source NASA/JPL-Caltech/SwRI/MSSS
Image processing: Kevin M. Gill.
1. Juno "heard" Europa's whisper
A few days before Christmas, the 2021 American Geophysical Society Fall Conference was successfully held in New Orleans. At the meeting, Juno mission scientists shared tracks collected during juno mission's recent close flyby of the giant Jupiter moon Ganymede. Juno principal investigator Scott Bolton shared a 50-second audio track generated from data collected during Juno's June 7 overflight. He said:
The soundtrack is wild enough to give you the kind of immersive shock that Juno felt when it first sailed past Europa more than twenty years ago. If you listen closely, you can hear the frequency of sound near the midpoint of the recording suddenly increase, which means that Juno has entered different areas of Europa's magnetosphere.
During the mission's 34th circumference to Jupiter, Juno flew to the closest point to Garnimede, at which point the spacecraft was less than 645 miles (1,038 km) from the surface of Garni Demede, and it flew at a relative speed of 41,600 miles (67,000 km) per hour. Juno's Wave instrument, which collects this data, makes adjustments to the radio and magnetic waves generated in Jupiter's magnetosphere. The scientists then shifted the frequency into the audio range, making the audio track below.
On June 7, 2021, Juno took this photo of Europa, Jupiter's largest moon
Source: NASA/JPL-Caltech/SwRI/MSSS
2, a magnetic large blue spot
Jack Connerney, a staff member at NASA's Goddard Space Flight Center, said at the fall AGU conference that he and his team have produced the most detailed map of Jupiter's magnetic field obtained to date. The map is a compilation of data collected by Juno from 32 orbits during its main mission. Scientists say it gives new insights into Jupiter's mysterious Great Blue Spot. The Great Blue Spot is a magnetic anomaly on Jupiter's equator. Juno's data suggests that the gas giant's magnetic field changed during the spacecraft's five years of operation. Relative to the rest of Jupiter's interior, the Great Blue Spot is drifting eastward at a rate of 2 inches (4 centimeters) per second. At this rate, the Great Blue Spot should circle Jupiter in about 350 years.
In contrast, the Great Red Spot (a long-term atmospheric anticyclone south of Jupiter's equator) is drifting westward at a faster rate, and it can circle Jupiter in about 4 and a half years
In addition, the new map shows that banded winds on Jupiter are stretching out the Great Blue Spot. Banded winds are jets of east-to-west and west-to-east jets on Jupiter that give Jupiter a unique banded appearance. This means that banded winds measured on the planet's surface can extend into the planet's interior.
The new magnetic field map also allows the scientists in charge of Juno to compare it to Earth's magnetic field. These data show the team that there is a dynamo-like phenomenon inside Jupiter, which is also the mechanism by which Jupiter generates a magnetic field. It occurs in metallic hydrogen, just under the shroud of a rain of helium.
This magnetic field map of Jupiter highlights the Great Blue Spot region, where there is a strong magnetic flux. The black line indicates a banded wind that distorts the Great Blue Spot. Band winds are powerful atmospheric winds on Jupiter that form boundaries along the visible atmospheric bands of Jupiter's uppermost layer. Southbound banded winds pull the Great Blue Spot to the west, and northward band winds pull the Great Blue Spot's magnetic field eastward.
图源NASA/JPL-Caltech/SwRI/John E. Connerney。
3. Earth's oceans and Jupiter's atmosphere
Lia Siegelman is a physical oceanographer and postdoctoral fellow at the Scripps Institute of Oceanography at the University of California, San Diego. She decided to study the dynamics of Jupiter's atmosphere after noticing that cyclones in Jupiter's polar regions appeared to have similarities with the ocean eddies she studied during her PhD studies. She said:
When I see the rich turbulence around Jupiter's cyclone, and all the filaments and smaller eddies, I think of the turbulence around the vortex I see in the ocean. These eddy currents in Earth's oceans are clearly visible in high-resolution satellite imagery. These eddies are actually manifested by the reproduction of plankton, and the reproduction of plankton is the tracker of flow.
NASA explains:
Simplified models of Jupiter's poles suggest that geometric patterns of those eddies observed on Jupiter arise spontaneously and never disappear. This means that the basic geometry of the planet can form these very interesting structures.
Although Jupiter's energy system is much larger than Earth's, understanding the dynamics of Jupiter's atmosphere helps us understand the physical mechanisms on Earth.
The picture on the left shows the phytoplankton of the Norwegian Sea on Earth, while on the right is the turbulent clouds in Jupiter's atmosphere. They look so similar, don't they? Oceanographers used juno's images to study the turbulent atmosphere at Jupiter's poles, helping us understand the forces that drive storms there.
图源NASA OBPG OB. DAAC/ GSFC/ Aqua/ MODIS
Image processing: Gerald Eichstadt.
4. Images of Jupiter's thin rings taken by Juno
At the fall AGU meeting, Juno's team also unveiled their latest image of Jupiter's faint dust rings, which were taken from inside the rings by the spacecraft's stellar reference unit navigation camera. NASA says:
The brightest thin bands and nearby dark regions can be seen in the images, which are associated with interstellar dust produced by Jupiter's two small moons, Metis and Adrastea. The image also captures the cantilever of persece.
Heidi Becker, lead researcher at the Juno Stellar Reference Unit instrument at NASA's Jet Propulsion Laboratory in Pasadena, said:
We can gaze at these familiar constellations from spacecraft 500 million miles away. They're still stunning, but everything looks the same as when we admire them in the backyards of the planet.
It's an awesome reminder of how small we are. A vast sea of stars, there are countless unknowns waiting for us to explore.
Juno took this image of Jupiter's thin rings, with the constellation Perseus clearly visible in the background
Source: NASA
Conclusion: Juno has been studying Jupiter and its moons since it arrived on the giant planet in 2016. These are four of its latest discoveries, which were unveiled at the December 2021 meeting of the American Geophysical Society.
BY：Editors of EarthSky
FY：Astronomical volunteer team
Author: Editorial Board of Earth and Sky
Belongs to the column: Astronomical Volunteer Team
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