They’ve only been seen on Earth and possibly on the Moon, but not on any other planets … until now. Human footprints? American flags? Aliens?
“11 transient bright flashes were detected in Jupiter's atmosphere using the UVS instrument on the Juno spacecraft. These bright flashes are only observed in a single spin of the spacecraft and their brightness decays exponentially with time, with a duration of ∼1.4 ms.”
As described in a new study published in the Journal of Geophysical Research: Planets, astronomers working on the Juno project – NASA’s tiny spacecraft that’s been orbiting Jupiter since 2016 – were looking at new data collected by its ultraviolet spectrograph instrument (UVS) when they spotted never-before-seen flashing lights. They had expected to see auroras but not flashes, according to the press release. They could be ‘sprites’ – tall, sinewy transient luminous events (TLEs) that occur in Earth’s upper atmosphere and are triggered by lightning discharges from thunderstorms below them – or ‘elves’, which are flat Emission of Light and Very Low Frequency due to Electromagnetic Pulse Sources, or sprite halos, which are flat sprites caused by weak ionization. Sprites, elves and sprite halos are generally red due to interaction with nitrogen, but the lights on Jupiter are blue or pink from the hydrogen in the gas giant’s upper atmosphere.
Wait a minute, you say … the Moon has flashes too, but doesn’t have much of an atmosphere and no thunderstorms.
Good observation. The flashes on the Moon are referred to as Transient Lunar Phenomena which, although they’ve been reported for a thousand years, are irreproducible on Earth and doubted by many scientists. They could be caused by gas escaping from underground cavities, meteor showers, electrostatic discharge from the surface cracking or just reflections or distortions in observation lenses.
While sprites and elves were predicted to be found on Jupiter, Juno had found nothing but lighting until recently. This cause was ruled out for these new lights because they occurred 186 miles (300 km) above the altitude where most of the planet’s lightning forms, and because the colors were different.
Is this big news? Rohini Giles, Juno scientist and lead author, thinks so.
"Now that we know what we are looking for, it will be easier to find them at Jupiter and on other planets. And comparing sprites and elves from Jupiter with those here on Earth will help us better understand electrical activity in planetary atmospheres."
That’s a good idea for the time when space probes travel at much lower altitudes and could be fried by electrical discharges.
Who would have thought a giant planet could have sprites and elves? This will make for some interesting sci-fi fairy tales.