Jupiter’s moons atmosphere glows up with hypnotic auroras

Using the HIRES (High-Resolution Echelle Spectrometer) of Keck Observatory in combination with a high-resolution spectrograph, scientists were able to discover the traces of Aurora on Jupiter's Moons- Io, Callisto, Europa, and Ganymede. The entire research was conducted at Large Binocular Telescope and Apache Point Observatory.

The Aurora Borealis is considered one of the most mesmerizing natural phenomena, which occurs when charged solar wind particles move around in the magnetic field. The phenomenon is not just a common occurrence on Earth but could also be observed on the surface of planets like Mars, Venus, Uranus, and Neptune. However, to the researchers' surprise, this natural light display was not witnessed on a planet this time but on moons.

"These observations are tricky because, in Jupiter’s shadow, the moons are nearly invisible. The light emitted by their faint aurorae is the only confirmation that we’ve even pointed the telescope at the right place," says Katherine de Kleer, Caltech professor, and lead author of one of two new research papers.

Reason for the occurrence

Researchers penned down the unusual nature of the formation of a few of these Auroras. Except for Ganymede, volcanic emissions occurring on the surface of Io could be the possible reason for such phenomena on the other three moons.

Once in the vacuum of space, the particle of the eruption reacts with sunlight. When the already irradiated emission makes its way to the atmosphere of other satellites, such auroras occur.

However, scientists believe that the constant fluctuating surface temperature of the moons and Jupiter's strong gravitational field may significantly affect the phenomena's brightness.

"Io’s sodium becomes very faint within 15 minutes of entering Jupiter’s shadow, but it takes several hours to recover after it emerges into sunlight, "explains Carl Schmidt, an astronomy professor at Boston University and lead author of the second paper. “These new characteristics are really insightful for understanding Io’s atmospheric chemistry. It’s neat that eclipses by Jupiter offer a natural experiment to learn how sunlight affects its atmosphere."

Scientists also add that the competition between the gases in the Gas Giant's atmosphere is another crucial factor. This factor provides the red color of the polar light of Jupiter's moons, the ability to get fifteen times brighter than the green light we are all familiar with.

Sodium compounds in the volcanic fumes of Io provide its aurora with the signature orange color, while potassium is the reason behind the crimson light.

The first research paper, "The Optical Aurorae of Europa, Ganymede, and Callisto" was led by de Kleer. The second research paper is titled "Io's Optical Aurorae in Jupiter's Shadow," and Schmidt led it. Both research papers were published this week in The Planetary Science Journal.