After nightfall, Jupiter glows in a way that rivals most theme parks (not to mention Earth's auroras) - but what is the source of this magic? Plasma.
Jupiter's auroras share some similarities to Earth's northern lights in terms of its spectacular X-ray outbursts. They're both triggered by magnetic field lines that vibrate. But Jupiter releases enough energy to momentarily power all of humanity. Jupiter's version is likewise invisible to us since it only glows in X-rays, unlike the Earth version. These were connected to the magnetic field. We now know what it is.
A team of researchers led by planetary scientists Zhonghua Yao of the Chinese Academy of Sciences and Wiliam Dunn of University College London have finally named it in their study titled "Revealing the Source of Jupiter's X-Ray Auroral Flares."
This ultraviolet image of Jupiter was created from data captured on 11 January 2017 using the Wide Field Camera 3 on the Hubble Space Telescope. The Great Red Spot and Red Spot Jr. (also known as Oval BA) absorb ultraviolet radiation from the Sun and appear dark in this view.
Plasma is to Blame For These Auroras
What was previously known was that auroras form when ions hit the Jovian atmosphere: that plasma exists among the magnetic field lines of the planet. Yao said per WIONews that these ions crash into the atmosphere and release ions in X-ray form when these magnetic field lines generate waves in the plasma.
Yao and his colleagues analyzed data from the Jupiter spacecraft Juno and the XMM-Newton satellite observatory to discover the science underlying these seeming sci-fi events. Space.com said the XMM-Newton space telescope is one of the most sophisticated X-ray observatories in the world. It can detect how many X-rays are emitted from Jupiter's poles quickly enough to disclose the intricacies of short-term changes in those emissions. One clue that would eventually lead to the answer was how often the X-rays pulsated. In tens of minutes, plasma electromagnetic waves, also known as magnetohydrodynamic waves, move down the magnetic field line.
Any magnetic field disruptions were considered, and the researchers discovered that the magnetohydrodynamic waves they were studying aligned with X-ray pulses. These were magnetohydrodynamic waves that had been compressed. They worked the same way as compressional waves, which have vibrations parallel to their travel direction and can only propagate through a medium (stuff in the space between) called plasma. Both the XMM-Newton and Juno measurements confirmed periodicities or repeated occurrences of a phenomenon over time. It was the proof needed to build computer simulations of what was going on.
Jupiter's Aurora Almost Surprisingly Similar to Earth's
Science Alert said Jupiter's auroras are, surprisingly, closer to Earth's than scientists imagined. Auroras on Earth go through a similar process to what occurs on Jupiter. When charged particles are blown in by the sun, they collide with our magnetic field and race towards the poles like they're on a cosmic roller coaster. They then collide with air molecules, which get ionized as electrons gain or lose, resulting in a dazzling light show. Auroras are more vivid, as in persistent, on Jupiter. This is because the particles come from the continually erupting moon Io's volcanic sulfur dioxide rather than the Sun.
Now let's look at the electromagnetic ion cyclotron (EMIC) waves linked to auroras on Earth. When charged particles are accelerated by an alternating electric field, they swirl around a spiral or circular track within the magnetic field at the same time, forming a cyclotron. These waves are found in magnetized plasmas and emit electromagnetic energy near cyclotrons. Yao hopes to use his newfound understanding in future explorations of other planets and moons.
The ions in Jupiter's magnetosphere are significantly higher energy than those found in other planets' magnetospheres, so don't anticipate a full-fledged lightscapade. Other gas giants, such as Saturn, may or may not have X-ray auroras. Nonetheless, this is an interesting look at how special space effects are made.
RELATED ARTICLE: Jupiter Moon Ganymede Has Water Vapor in Its Atmosphere! Could This Be Common on Icy Bodies in the Solar System?
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