Northern and southern lights are one of the most incredible spectacles we see on Earth, but Jupiter may give them a run for their money.
The gas giant has auroras as well, but they are significantly larger and cover an area much bigger than Earth. They are also 100 times more energetic than what we see here at high latitudes. In fact, they are so energetic that they shine in the ultraviolet.
And, using the Hubble Space Telescope, astronomers have captured new images of this incredible spectacle of glowing lights. These observations, in combination with data from the Juno probe (which arrives at Jupiter next week), will allow scientists to better understand how the magnetic field of the planet interacts with the auroras.
“These auroras are very dramatic and among the most active I have ever seen,” said the University of Leicester's Jonathan Nichols, principal investigator of the study describing the findings, in a statement. “It almost seems as if Jupiter is throwing a firework party for the imminent arrival of Juno.”
Auroras are caused by charged particles, mostly electrons and protons, from the solar wind hitting the upper atmosphere. This process leads to the ionization and excitation of high-altitude gasses that emit lights of different colors depending on the gas and the energy of the impact.
Jupiter's magentic field (20,000 times stronger than Earth's) accelerates charged particles towards the poles, and there they slam into the atmosphere, emitting ultraviolet light. In the timelapse videos, the auroras are seem circling the planet's north pole, rising and waning, changing shape, and in general reflecting the complex magnetic enviroment that surrounds Jupiter.
The Jovian auroras were first discovered in 1979 by NASA’s Voyager 1. The probe saw a thin ring of light on Jupiter’s night side that was remarkably similar, although stretched out, to Earth’s own auroras. Later, it was realized that their peak luminosity is in the ultraviolet.
Since then, Jupiter’s polar lights have intrigued astronomers, with Hubble now observing the gas giant on a daily basis to highlight the changes in the system.
Size and intensity are not the only differences between terrestrial and Jovian auroras. On Jupiter, the auroras rise and wane but they never stop. That’s because unlike Earth, the auroras are produced by more than just the solar wind from the Sun. Jupiter has such a strong magnetic field that it traps not just the stream of electrons and protons from the Sun, but also the material spewed into space by its active moon Io.
Hubble’s observations are ongoing, and the analysis, combined with Juno data, will take several more months. Hopefully, we will soon unlock the secrets of the Solar System’s best auroras.