(ORDO NEWS) — New observations have shown that the auroras on Jupiter’s four largest moons are deep red, and those on Io are also hues of yellow and orange.
When the solar wind interacts with the atmosphere, it can excite the atoms entering it, causing them to radiate.
Magnetically guided solar wind particles enter the upper atmosphere at the poles, resulting in auroras.
Such a glow can be observed not only on Earth, but also on other planets of the solar system, including Jupiter, where they are especially intense.
Jupiter has an exceptionally powerful magnetosphere, and its gaseous envelope consists mainly of hydrogen and helium, so the auroras of this giant are most visible in the blue and ultraviolet regions of the spectrum.
However, such processes are not limited to planets. The same Jupiter is surrounded by dozens of satellites, including the four largest discovered by Galileo – Io, Europa, Ganymede and Callisto.
Observing their auroras is much more difficult, but recently astronomers working at the Hawaiian Keck Observatory were able to observe the glow on all four of the Galilean satellites
It is not easy to see the auroras of the Galilean moons, because this glow is very dim and “overlapped” by the radiation of the Sun reflected from the surface.
Therefore, scientists conducted observations while the satellites were in the shadow of a giant planet. During such periods, they become almost invisible.
“The faint glow of the auroras is the only evidence that we pointed the telescope in the right direction,” said Katherine de Kleer, one of the authors of the work.
The atmospheres of all four satellites are relatively rich in oxygen, although much more rarefied than on Earth.
On Europa, Ganymede and Callisto, oxygen is formed due to the sublimation of ice from the surface and the subsequent decomposition of water molecules under the action of radiation.
On Io, it appears due to the decay of sulfur dioxide molecules. One way or another, but the presence of molecular oxygen colors the auroras of satellites in a deep red color.
On Europa and Ganymede, this radiation goes even into the infrared region of the spectrum.
In addition, on Io, which is considered the most volcanically active body in the entire solar system, the atmosphere is filled with emissions containing sodium and potassium chlorides.
They give the local auroras unusual new colors, including yellow-orange.
The auroras of Jupiter’s Galilean moons are strongly influenced by its magnetic field. Therefore, their intensity varies greatly as the huge planet rotates.
It is curious that the satellites themselves can influence the Jupiterian auroras. Previously, it was shown that the emissions of Io’s volcanoes, reaching its atmosphere, make the “crowns” near the pole flare brighter.
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