Earth does not offer the unique privilege in our solar system of seeing the colorful aurora. American astronomers have discovered that visible auroras are observed on all four of Jupiter’s large moons: Io, Europa, Ganymede and Callisto.

For the first time, auroras were detected on the last two satellites, and new features of an impressive atmospheric phenomenon were discovered on the first two satellites. Auroras exist on other celestial bodies, but usually at wavelengths invisible to the human eye.

Using the 10-meter Keck Opto-Infrared Telescope on Mount Maunakea in Hawaii, scientists published in the Planetary Science Journal under the direction of Caltech (Caltech) professor Katherine de Kleer reported that in all cases, the aurora is caused by a powerful giant magnetic field of the giant planet Jupiter.

The auroras on the four large moons are similar to the aurorae at Earth’s poles, but the gases on Jupiter’s moons are much thinner, resulting in a deep red glow nearly 12 times brighter than the green on Jupiter’s moons on our own planet.

On Io, columns of gases and dust of volcanic origin, huge, reach a height of hundreds of kilometers, and because they contain various salts, they give additional colors to the aurora there, in particular a yellowish-orange glow, reminiscent of night lighting in cities on Earth.

“The brightness of the different colors of the aurora tells us what the atmosphere of these satellites is likely to be made of. “We have found that molecular oxygen, similar to what we breathe here on Earth, is likely a key component of the atmospheres of these icy moons,” de Clier said. On the other hand, there is little evidence for water vapor, although Jupiter’s three large moons are estimated to contain oceans of liquid water beneath their thick icy surfaces.

Because Jupiter’s magnetic field is tilted, the auroras on its moons change in brightness as the planet rotates.

^{Source: RES-IPE}