General, Research, Technology

Jupiter's moon Europa glows in the dark. But why?

One of Jupiter's moons glows in the dark. At first glance, this is perhaps not surprising, because our own moon glows in the dark, reflecting the light of the sun. Jupiter is far from here, but our star, despite its distance, illuminates the planet and its many moons, including Europe. Europe, as the reader probably knows, is different from the other 78 moons of the gas giant. So, according to the results of recent studies, Europe can glow even on its night side, flickering without any help from the Sun. Since Jupiter's magnetic field is the largest of all other planets in the solar system, radiation within its boundaries is many millions of times more intense than radiation near Earth. High-energy particles constantly bombard Europe - a world with a thin atmosphere, which is slightly smaller than the Moon. And when these particles hit the ice-covered surface of Jupiter's moon, a chemistry quirk can make the moon glow in the dark.

An illustration of Jupiter's moon Europa, showing what it might look like when it glows in the dark.

Why is Europa a special moon of Jupiter?

The surface of this icy world is as smoothjust like the surface of our own planet, except for a few cracks caused by Jupiter's gravitational tides. Although Europa is the sixth closest moon to the gas giant, its magnetic field helps protect it from radiation from its host planet.
Moreover, the surface of Europa is so cold that the ice on it is as hard as concrete.

Observations by spacecraft andground-based telescopes show that the area is littered with chemicals such as sodium chloride and magnesium sulfate. On earth, we know them as table salt and Epsom salts.

Europe's atmosphere is mostly oxygen, although it is too thin for humans to breathe.

Salts scattered across the surface of Europe area necessary ingredient for a strange glow. As it turned out, the radiation of Jupiter has the same effect on these compounds as a large cup of coffee on a person. Drinking too much coffee can make you feel overexcited. Roughly the same thing, according to The Atlantic, happens with molecules and atoms. But molecules and atoms cannot remain in an excited state for a long time, and therefore return to their normal state, emitting energy in the form of visible light - photons.

The surface of Europa in the lens of the Juno camera

As noted by the authors of the work published inin Nature Astronomy magazine, Europa's glow is more than a beautiful light show; it could help researchers learn more about what lies beneath its ice crust. Since the Voyager missions first flew past Europa in the 1970s, scientists have believed that this moon has a salty ocean, warmed by the internal heat warmed by Jupiter.

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When Europe revolves around the planet in its own wayan elongated orbit, Jupiter's gravity stretches and contracts the entire moon, creating heat that keeps the ocean liquid. Scientists now suspect that microbial life forms may exist in Europa's marine oceans. I talked in more detail about what life can be on the satellite of this gas giant in this article.

Space in the laboratory

Scientists have modeled many of Europa's unusual features in a lab to recreate the moon's environment. But they weren't ready for what they found: the greenish or bluish light is emitted by the icy moon due to radiation from its host planet, Jupiter. Depending on the compounds included in theice, the glow can appear green or blue with varying degrees of brightness. The results are detailed in a paper published in the journal Nature Astronomy.

When researchers modeled Europe,bathed in radiation, they emitted a glow that ranged from green to bluish and neon white, depending on which salts the scientists mixed with the ice. It is noteworthy that outside the laboratory, this effect does not occur naturally, either on our Moon or on Earth. The most similar glow on our planet comes from the aurora borealis, which occurs when particles drifting from the Sun meet particles trapped in our planet's magnetic field.

As the authors of the study write in their work,“This luminous effect is seen throughout Europe, but is probably too dim to be noticed in the sunshine on the daytime side of the moon. On the dark side, Europe casts its dreamy glow into the darkness of space. "

Columns of water erupting over Europe as seen by the artist.

According to the current leading theory,Over the course of many millions of years, materials from the deep waters of Europe rose to the surface and vice versa. The presence of salts on the surface of Europa's ice and within it may be a direct indication that ocean water was rising from below, bringing these salts and possibly other materials to the surface of the satellite.

Life in Europe

The new discovery not only highlightsthe uniqueness of Europe, but can also help astronomers detect signs of life on an icy moon. Scientists have long suspected that beneath the cracked icy surface of Jupiter's moon lies a vast ocean of liquid water, twice the size of the oceans on earth. And this ultra-cold water can be a haven for alien life.

You will be interested: Why do we need to colonize the moon of Jupiter?

Let me remind you that NASA is preparing to launch a mission toEurope in the mid-2020s. The Europa Clipper will study the surface of the moon, and the researchers behind the new discovery also hope to be able to observe Europa's glow in real life. At the same time, the authors of the work note that due to radiation directly on the surface of the icy moon, any microorganisms are unlikely to be able to survive.

“We probably won't find Europa on the surfacefish, but we could find some interesting chemistry that would help us understand what chemical processes may be available for life in the subglacial ocean, ”write the authors of the scientific work.