Astronomers spotted auroras for the first time on two of the biggest Galilean moons of Jupiter. New features of Io and Europa's auroras have also been discovered.
Previously Unseen Auroras Dazzling Over Galilean Jupiter Moons
The Space Academy reports that these previously unseen auroras can be spotted when an eclipse takes place.
While earth also has ethereal glows of its own, it is not the only planet to host such light shows. Research has recently revealed the presence of auroras on Europa, Io, Callisto, and Ganymede, which are Galilean moons of Jupiter.
The studies published in the Planetary Science Journal are the first ones to document that if an individual stands on the Callisto or Ganymede surfaces, they will be able to spot the ethereal glows above them. The research also illustrates new kinds of auroras across Europa and Io.
These new auroras were captured by the astronomers as they navigated through telescopes from New Mexico, Arizona, and Hawaii. Years were spent monitoring satellites getting swallowed over and over again by the shadow of Jupiter, and then they would emerge once more.
The New York Times reports that being able to catch such ephemeral dazzles on moons that are far away, fast-moving, and diminutive can be quite a hard feat to pull off. However, according to planetary astronomer Katherine R. de Kleer from the California Institute of Technology, auroras are always there when an eclipse takes place.
Galilean Auroras
Compared to the auroras that can be found on earth, Galilean auroras have a different way of coming to be. In earth's case, energetic particles and magnetic fields that are expelled from the sun arrive on earth and get trapped within earth's very own bubble of magnetism. These particles plunge to the south and north poles of the magnet and crash with vapor molecules within the top atmosphere. This briefly leads to energizing and allows the emergency of visible light hues and glows.
The case is quite different from Jupiter's Galilean moons. Aside from Ganymede, the huge moons lack the magnetic bubbles found on earth. Rather than being attributed to such phenomena, their aurora is largely dependent on the Io moon. The New York Times reports that the moon's detrimental atmosphere keeps on shedding out into space. The remnants interact with sunlight and get electrified. While much of these get swallowed by the magnetic bubble of Jupiter, some of the castoffs enter the atmosphere of Io or the vaporous sheaths of other moons. This then ignites the ethereal glows on these Galilean moons.
What Auroras Reveal About the Atmosphere
The researchers examined the moons covered in darkness in order to reveal these glows. They confirmed that the skies of all four moons had red and green hues that mirrored those of earth's. Even if they are less luminous compared to earth's auroras, they have their own intricate and intriguing features.
For one, because of the thin atmosphere, red hues have a more intense shine compared to their green counterparts. Moreover, on earth, different colors depend on the altitude. However, the colors in Io have a rainbow effect mix of some sort.
The auroras' colors show hints regarding the ingredients that make up the atmosphere. Molecular oxygen is a dominant component that can be found across the atmospheres of Ganymede, Europa, and Callisto. The presence of such a component explains the red and green tints. The sickly orange hue from Io can be attributed to sodium compounds. Crimson light, on the other hand, is from potassium.
The clear auroras suggest that there is minimal water vapor across the Ganymede and Europa atmospheres. The Space Academy reports that such findings are quite a shock, given that Europa and possibly Ganymede hold great bodies of water under their carapaces.
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