September 28, 2020
Various plasma instabilities are found on Jupiter.
NASA launched the Juno spacecraft on August 5, 2011. Its primary mission includes analyses of Jupiter’s massive plasmasphere: how do its electromagnetic influences affect the Jovian system. Since Jupiter radiates more energy than it receives from the Sun, astronomers think that some kind of internal dynamo, acting like a generator, “must be” creating the excess. However, there are processes occurring on Jupiter that are now coming to light.
Jupiter is an electrically active world, far more so than computer simulations predicted. Based on what was surmised about Jupiter, a 5 gauss magnetic field was assumed to exist. When Juno entered orbit and began its scientific measurements, levels as high as 9 gauss were found. Compare those readings to Earth’s .5 gauss field and the enormity of Jupiter’s electromagnetic energy can be deduced. Its field is also irregular, leading some astrophysicists to suggest that there is an anomalous structure in Jupiter’s core.
Recently, for example, Juno discovered jet-streams on Jupiter that run farther down into its atmosphere than previously thought: over 3000 kilometers deep. Why the atmospheric bands are so deep is a mystery, since they have always been associated with superficial weather patterns.
According to a recent press release, the South pole of Jupiter also exhibits an unusual grouping of phenomena. Multiple vortices encircle a central whirlpool of gas and dust. The structures are warmer than the surrounding cloud bands, but are still near absolute zero temperatures.
Perhaps the Great Red Spot that has persisted for more than 300 years can provide additional clues to how the polar vortices are formed and stabilized. The consensus opinion is that it is a cyclonic storm driven by rising heat from below, because it is warmer than its surroundings. However, exactly how it was formed and why it has persisted for so long are mysteries. Wind speeds around its perimeter have been measured at 635 kilometers per hour, twice as fast as a terrestrial tornado.
As previously written, Jupiter and its moon, Io, dissipate 2 trillion watts between them. That flow of electric charge causes lightning in Jupiter’s upper atmosphere, along with aurorae at the poles. Since Jupiter is obviously an electrical environment, it is there that some answers can be found. Rotating charged bodies produce dipolar electromagnetic fields, whether they are gas giants or rocky planets. Why some planets like Earth and Mercury possess magnetic fields, while Venus and Mars do not demands further investigation. However, the basic physics of charged objects in motion generating electromagnetism is not debated.
Plasma is not a substance, it is a state of matter. Any material can become a plasma if electrons are stripped from atomic nuclei, causing charge separation to occur. Whenever there are regions of opposite charge—and Juno team members detected a gravitational asymmetry inside Jupiter that most likely contributes to charge separation—double layers will form and an electric field will develop. An electric field, no matter how weak, accelerates charged particles. Depending on the characteristic of any given plasma, it will be affected differently by electricity. This could explain why the polar vortices are so distinct, Jupiter’s electric field accelerates plasmas at different rates.
Coupled with the cloud band observations, the “massive cyclones” exhibit distinct temperature bands, high wind speeds and endurance—they appear to be permanent fixtures. Charge separation in plasma could explain those anomalies.
The Thunderbolts Picture of the Day is generously supported by the Mainwaring Archive Foundation.