NASA has recently made some groundbreaking discoveries that have shed light on the unusual polar lights discovered some time ago on the mighty Jupiter. The polar lights, also known as auroras, have been observed for many years, and until now, have puzzled experts. However, with the help of the space probe Juno, experts have succeeded in coming closer to the true background of these spectacles.

Auroras are a luminous phenomenon caused on our blue home planet by excited nitrogen and oxygen atoms of the high atmosphere. They are probably one of the most majestic natural spectacles that our earth has to offer. However, in view of the overwhelming beauty of auroras, we should not ignore one fact: they are not a phenomenon that occurs exclusively on our terrestrial home. If a planet has its own magnetic field and atmosphere, the unique formations can also appear there.

How the lights in the sky are created on earth has been known for quite some time. While quite a few of our ancestors still believed that they were supernatural phenomena, we now know that auroras are created when electrically charged particles of the solar wind hit nitrogen and oxygen atoms in the earth’s atmosphere and ionize them. The recombination that starts shortly thereafter, or in other words, the neutralizing unification of electrically positive and negative charge carriers is finally accompanied by the emission of light.

Much more mysterious, however, is the background that leads to the formation of such auroras on the imposing Jupiter. Since NASA’s Voyager 1 spacecraft transmitted the corresponding findings to Earth in 1979, we have known that the breathtaking light shows also occur on the largest representative of our planetary system. In the following decades, the auroras on Jupiter were to be observed many more times with the help of ground-based and earth-orbiting observation instruments such as the Hubble Space Telescope.

A striking characteristic of these phenomena was soon recognized: the so-called twilight storms. In detail, this refers to short-lived but intense brightenings and broadenings of Jupiter’s auroras, which always occur where the gas giant’s atmosphere emerges from darkness after the end of Jupiter’s night. Before NASA’s Juno spacecraft reached the giant celestial body in July 2016, experts were unable to observe the process up close. In fact, everything that happened on the night side of the planet remained hidden from the researchers until now.

In the context of the investigation of the Jupiter aurora, it’s not impossible from the earth to take a look at the night side of the poles. While Juno is not the first unmanned spacecraft to visit the realms of Jupiter, it’s the closest. Galileo, Voyager, and Cassini approached the planet from quite large distances without flying past its poles. So for decades, scientists were unable to draw a holistic picture of the gas giant. The data currently being collected and transmitted by Juno thus represent a turning point in the history of Jupiter exploration.

Novel insights thanks to Juno’s mission. Experts realize that the unusual light storms occur on the night side of the planet as soon as Jupiter rotates. The approaching sunrise virtually rotates with it to the dayside, as a result of which the already complex bright auroras become even more intense, ultimately radiating hundreds to thousands of gigawatts of ultraviolet light into the universe. This striking increase in auroral brightness, which occurs on Jupiter during dawn, means, in detail, that the morning storms release at least 10 times more energy into the gas giant’s upper atmosphere than ordinary auroral displays.

Viewed as a whole, however, the spectacles on Jupiter show certain parallels to terrestrial phenomena, the so-called substorms. These occur on our blue home planet as a result of temporary disturbances in the magnetosphere.