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Jupiter’s moon Europa has ice that can glow green in the dark

By Leah Crane

The surface of Jupiter’s icy moon Europa

NASA / JPL / University of Arizona

Jupiter’s moon Europa can glow in the dark. Laboratory experiments have shown that the type of ice covering the lunar surface glows under radiation, which could help us figure out the makeup of its frozen plains and subterranean oceans.

Because of the way Jupiter’s strong magnetic field accelerates charged particles, Europe is constantly bombarded by high-energy electrons. Murthy Gudipati of NASA’s Jet Propulsion Laboratory in California and his colleagues studied how Europe’s icy surface might respond to this bombardment by blasting electrons on ice samples that are enriched with molecules that may be found on Europe.

When the electrons hit molecules in the ice, the molecules fall apart and their atoms absorb some energy. The atoms then re-emitted this energy as light, creating an eerie, greenish glow. This was lighter or darker depending on the type of molecule – for example, adding sodium chloride reduced the glow.


“If you imagine standing on Europe and looking at the glow beneath your feet, the brightness is similar to standing outside in the light of the full moon and then looking at the ground,” says Gudipati. “But Europe’s surface is a very dangerous environment. While we can imagine standing on it, a few seconds on Europa would probably kill a person.”

While visiting Europe in person may not be a beginner, NASA already has a spacecraft in the works, the Europa Clipper mission, scheduled to start in 2024 and examine the moon as it orbits Jupiter. It could potentially watch the glowing ice and use its brightness to determine its composition.

“There is evidence that there are oceans beneath the ice on Europe that might be habitable, and if so, the minerals and salts in that ocean should be exchanged with the surface,” says Gudipati. If we find out what the surface is made of, we can better understand whether the seas of Europe have the necessary ingredients for life.

Journal reference: Nature Astronomy, DOI: 10.1038 / s41550-020-01248-1

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