Aurorae are natural light displays that occur in the polar regions of the Earth. They are created when charged particles from the Sun collide with the Earth’s magnetic field and interact with the gases in the Earth’s upper atmosphere. These particles are primarily electrons and protons that are emitted by the Sun during a solar storm or coronal mass ejection.
When these particles enter the Earth’s atmosphere, they collide with the oxygen and nitrogen molecules in the air. This interaction causes the molecules to become excited and emit light in the form of photons.
Not many people know that aurorae can even form on other planets in our solar system that have magnetic fields and atmospheres. In fact, aurorae have been observed on several planets, including Jupiter, Saturn, Uranus, and Neptune.
Aurorae spotted on Ganymede, Io, Europa, and Callisto
Astronomers have used the W. M. Keck Observatory in Hawaiʻi to discover that all four of Jupiter’s major moons, Io, Europa, Ganymede, and Callisto, display aurorae at visible wavelengths, according to SciTechDaily. The team from Caltech and Boston University observed the moons in Jupiter’s shadow to detect their faint aurorae, which are caused by the planet’s strong magnetic field, without interference from sunlight reflected off their surfaces. They utilized the High-Resolution Echelle Spectrometer (HIRES) at the Keck Observatory, as well as spectrographs capable of high-resolution from the Large Binocular Telescope and Apache Point Observatory, to make these observations.
Katherine de Kleer, a Caltech professor, stated as the same publication mentioned above quotes:
The brightness of the different colors of aurora tell us what these moons’ atmospheres are likely made up of,
We find that molecular oxygen, just like what we breathe here on Earth, is likely the main constituent of the icy moon atmospheres.
Ganymede is the largest moon in our solar system, and it orbits the planet Jupiter. It was discovered in 1610 by the Italian astronomer Galileo Galilei, along with three other Jovian moons.
