Scientists were able to find out exactly how the aurora borealis form on Jupiter. The European Space Agency (ESA) announced that they have solved a 40-year-old puzzle.
On Earth, the aurora is created when electrically charged particles from the sun (which reach our planet via the solar wind) are deflected toward the poles by Earth’s magnetic field and collide with particles in the atmosphere. On Earth, the aurora can only be seen in the so-called auroral ovals (between 65 and 80 degrees north and south latitudes). Above these latitudes, it does not occur due to open magnetic field lines, which are associated with the solar wind.
If things were the same on Jupiter, no major auroras would be expected on this planet. So the phenomenon of light has different characteristics. Since the gas giant also has closed field lines above the main elliptical aurora, which can leave the planet on one side and return to the other, they also occur at the actual poles. In addition, the aurora pulsates regularly and sometimes varies at the north and south poles.
Based on X-rays from the aurora borealis on Jupiter, scientists have already discovered that they are caused by electrically charged atoms (ions) colliding with the atmosphere. But how these charged particles entered the atmosphere of the largest planet in our solar system in the first place remained a mystery until now.
Astrophysicist Zhonghua Yao (a researcher at the Institute of Geology and Geophysics in Beijing and in the past affiliated with ULiège, among others) and several colleagues have developed computer simulations that link pulsating X-ray auroras with closed magnetic fields that originate deep in Jupiter, then enter millions of kilometers into space. Then you come back.
A group of astrophysicists led by Yao and William Dunn (Mullard Space Science Laboratory at University College London) used these simulations to discover exactly how ions end up in Jupiter’s polar regions. To do this, they analyzed data from the ESA XMM-Newton satellite and NASA’s unmanned Juno spacecraft. Orbiting Earth, XMM-Newton observes Jupiter from a distance using X-ray telescopes, while Juno orbits the gas giant, gathering data within the planet’s magnetic field.
fluctuations of the magnetic field
They found that the X-ray auroras are caused by fluctuations in Jupiter’s magnetic field. As the planet rotates, it pulls with it its magnetic field, which collides with charged particles from the solar wind and compresses. These compressions heat up the particles trapped in the magnetic field, resulting in electromagnetic ion cyclotron waves, or EMIC waves. In doing so, the ions are directed millions of kilometers through space along magnetic field lines, until they collide again in the atmosphere, creating the aurora borealis.
“What we see in the Juno data is a beautiful sequence of events. We see the compression happen, we see the EMIC wave arise, we see the ions, and then we see the ions travel along the field lines,” explains Dan. from. “A few minutes later, XMM saw a burst of X-rays.”
The fact that scientists have now detected X-ray auroras on Jupiter also helps us understand other planets with auroras. “This is a fundamental process that applies to Saturn, Uranus, Neptune and possibly also the exoplanets (planets that orbit stars other than the Sun),” Yao says.
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