Astronomers detect new aurorae on Jupiter's 4 largest moons
Astronomers have spotted new aurorae, at visible wavelengths, on all four major moons of Jupiter -Io, Europa, Ganymede, and Callisto. Surprisingly, the Jovian moons show the same auroras seen at Earth's poles, which are caused due to oxygen molecules. However, since the gases on Jupiter's moons are thinner, the red color glow is intensified by nearly 15 times more than the familiar green one.
Why does this story matter?
- It might be a lesser-known fact that the largest planet in the solar system is also home to stunning auroral displays like the ones on our home planet. In fact, Jupiter has the brightest auroras in the solar system.
- The occurrence of auroras on Jupiter was first discovered almost 40 years ago, in 1979, by NASA's Voyager 1 space probe.
Observations were made when the moons were in Jupiter's shadow
The observations were made using the W. M. Keck Observatory in Hawaii, the Large Binocular Telescope in Arizona, and Apache Point Observatory, in New Mexico. Astronomers observed the moons in Jupiter's shadow so that the aurorae, caused by the planet's strong magnetic field, could be spotted without any interference from the sunlight reflected off of their surfaces.
"These observations are tricky"
"These observations are tricky because in Jupiter's shadow, the moons are nearly invisible," said Katherine de Kleer, lead author of one of two new research papers published in The Planetary Science Journal describing the discovery. "The light emitted by their faint aurorae is the only confirmation that we've even pointed the telescope at the right place," she added.
How do auroras form on Earth and Jupiter?
On both Earth and Jupiter, auroras are formed when charged particles like electrons interact with the planet's magnetic field lines, which then subsequently enter the planet's atmosphere, giving rise to the glow. On Earth, the most intense auroras are caused by solar storms, which are a result of high-energy particles ejected from the Sun that make their way to the planet.
Jupiter's Io moon also sparks auroras on the planet
When these particles enter the atmosphere, they interact with gases present there, sparking off red, green, and blue glows at the poles. Along with solar winds, Jupiter has an additional source for auroras- Io, the planet's innermost moon, known for its numerous and massive volcanoes.
Io is known for its massive volcanoes
On Io, the volcanic plumes of gas and dust are so large, that they can shoot hundreds of kilometers high. These plumes contain salts like sodium chloride and potassium chloride, which break down to produce multiple colors. For instance, sodium imparts a yellow-orange glow. The investigation also shows potassium auroras at Io in infrared light. This has not been detected anywhere else before.
Auroral colors provide information on Jovian moons' atmospheres
What's significant about these findings is that they shed more light on the Jovian moons. "The brightness of the different colors of aurora tell us what these moons' atmospheres are likely made up of," said de Kleer. "We find that molecular oxygen, just like what we breathe here on Earth, is likely the main constituent of the icy moon atmospheres."
The investigation reveals an interesting finding
There is another interesting finding as well. On Europa and Ganymede, oxygen auroras were seen in infrared wavelengths. So far, this phenomenon has not been seen on another planet other than Earth.