the California Institute of Technology (Caltech) and Boston University researchers A Keck Giant Telescope With the help of two other ground-based observatories, the hitherto unknown type of aurora was detected on Jupiter’s four largest moons. This could happen when the moons were in the shadow of Jupiter, that is, they did not receive direct sunlight, so the glow of the aurora borealis that formed on them as a result of the very strong magnetism of Jupiter could be detected.
“These observations are very complicated, because in the shadow of Jupiter it is almost impossible to see its moons. The faint glow of the aurora borealis indicated that we were pointing the telescope in the right direction, ”explains Professor Catherine de Claire, Planetary Science Journal Leader of the research published in the journal.
Fantasy image: Aurora borealis on Ganymede, Jupiter and the Sun in the background, and the Keck Observatory used for observing below.
Source: Julie Inglis
All four of the Galileo moons showed aurorae of oxygen origin, similar to that on Earth, but because the gases on these moons are much rarer than on Earth, the deep red aurorae appeared 15 times brighter than the more common bright green version. (During the formation of aurorae, the excited atoms lose their excitement when they collide with another atom, after which they can no longer emit light, which is why they shine due to the fact that they are rarely found in the given atmosphere, so they can collide often.)
The aurorae of Ganymede and Europa also shine in the infrared, and this is the first time we’ve seen the aurora in infrared on a celestial body other than Earth. Io, the most volcanic moon in the solar system, has additional interesting features. As countless molecules undetectable on other moons, such as sodium chloride or potassium chloride, enter the atmosphere from the surface of this young moon, these molecules add additional colors to the young moon’s sky. Sodium emits a glow similar to the orange glow of classic streetlights, but potassium creates a kind of infrared afterglow not seen anywhere before.
Because individual gases can emit their distinct colors, specialists can infer the composition of these moons’ atmospheres from observations of the aurora borealis. According to observations, molecular oxygen is most common in the atmosphere of these moons – as is Earth’s atmosphere, which we can breathe at home. The observations also revealed that there is a trace amount of water vapor in the atmosphere around these moons, and this issue has been the subject of scientific debates for a long time.
It is also worth bearing in mind that if we could spot these aurora borealis from here on Earth, what a wonderful spectacle they would present locally, if viewed from the surface of one moon or another!
