NASA says Jupiter’s funky moon Europa may glow in the dark

If you managed to get to Jupiter and then looked at the dark side of its moon Europa, you might be blown away by an ethereal glimmer. The fascinating icy moon may sport a glow-in-the-dark nightside triggered by blasting radiation. 

Scientists at NASA’s Jet Propulsion Laboratory have figured out what Europa’s glow might look like and how it ties into the composition of the moon’s ice. The team published a paper on the potential glow in the journal Nature Astronomy on Monday.  

Here on Earth, we’re used to seeing our moon shining back at us as sunlight reflects off its surface. That’s not how Europa’s special gleam would work. Europa’s ice is likely mixed with salts (which we know as Epsom salt and table salt). Mix in some high-energy radiation blasted out by Jupiter and you would get a lovely glow-in-the-dark effect.

“If Europa weren’t under this radiation, it would look the way our moon looks to us — dark on the shadowed side,” said JPL’s Murthy Gudipati, lead author of the study. “But because it’s bombarded by the radiation from Jupiter, it glows in the dark.”     

To dive deeper into these ideas, researchers at JPL built a special instrument with an amazing name: Ice Chamber for Europa’s High-Energy Electron and Radiation Environment Testing (Ice-Heart). Experiments conducted with Ice-Heart mimicked conditions on Europa and showed how various ice-and-salt compositions generated distinct glows.

“Different salty compounds react differently to the radiation and emit their own unique glimmer,” NASA said in a statement on Monday. “To the naked eye, this glow would look sometimes slightly green, sometimes slightly blue or white and with varying degrees of brightness, depending on what material it is.”  

Europa likely harbors a hidden ocean under the ice. That’s one of the reasons scientists think it could be a great place to seek out signs of alien life, and also why NASA is sending its Europa Clipper spacecraft mission to get a closer look. 

NASA is aiming to launch Europa Clipper in the mid-2020s. The spacecraft will make close flybys of the moon, but it won’t be physically dipping into the ice or the interior ocean to look for microbes. It could still tell us a lot about the potential habitability of Europa.  

This research could help scientists make sense of data sent back by Europa Clipper as they investigate the chemical composition of the moon’s ice. If we’re lucky, we might also get some lovely visuals of Jupiter’s nightlight to go along with it.