What caused the toxic snowfall in The Eternaut? Details from the Netflix series, explored

Netflix's new sci-fi series, The Eternaut, dropped on April 30, 2025. Helmed by Bruno Stagnaro, this six-episode Argentinian series is based on the graphic comic by the duo Hector German Osterheld and Francisco Solano Lopez. The series is based on the aftermath of a deadly and unnatural snowfall in Buenos Aires that kills everybody exposed to it.

It follows Juan Salvo and a small group of survivors in a post-apocalyptic world trying to navigate and find answers to a deadly snowfall that killed everybody except for them. Turns out it's not a natural event, but what caused this bizarre phenomenon? A chilling explanation rooted in science and even alien intervention.

What caused the toxic snowfall in The Eternaut? Favalli's Theory — Earth's magnetic collapse

Even though the Netflix series does not explain the reason behind the toxic snowfall that killed anybody who was exposed to it, a pivotal character from the series does shed some light.

An electrical engineer, Favalli, one of the survivors of the attack, said that it occurred due to a major shift in Earth's magnetic field. He also gave a plausible explanation for his theory. He revealed that he got the idea when his compass stopped working. Favalli was sure some phenomenon disrupted the Earth's magnetic field as the poles were reversed/weakened due to an external force.

Usually, the Van Allen radiation belts protect life from solar radiation, but as the magnetic poles were reversed/weakened, the radioactive elements could have mixed with the snow. Thus turning the flakes into a deadly radioactive element, killing life on Earth.

His theory becomes more believable when the snowfall stops, and the compasses confirm that the poles have flipped. While scientifically speculative, the show suggests this magnetic disruption was not natural, but rather that an external force is behind it.

Who was behind the deadly snowfall attack in The Eternaut?

The snowfall wasn't a natural disaster. It was the first stage of an upcoming alien invasion. Yes, it was indeed the aliens! The show does not give much information about the reason for the alien attack or their next move.

At the end of the series, the show's protagonist, Juan Salvo, discovered an extraterrestrial force, led by a mysterious entity, an eerie alien hand, orchestrated the magnetic shift, and is also the reason behind the controlled army in Campo de Mayo. The alien hand uses some form of music to control the human and the giant bugs.

The lethal snow served two purposes- one was mass extinction (wiping out the entire population), the other was psychological warfare (leaving the survivors disoriented and thus easy targets for the next phase).

Once the snow stopped, the aliens deployed beetle-like creatures and began manipulating the human mind. The snowfall was thus an opening to a larger, sinister plan.

A Weaponised Apocalypse: The Eternaut

The Eternaut presents the toxic snow as both a scientific anomaly and an alien weapon. By destabilizing the Earth's magnetic field, the invaders turned the planet's own defenses against humanity. The result? A haunting, slow-burning apocalypse.

For sci-fi fans, the show's blend of real-world science and extraterrestrial terror makes it uniquely terrifying. And with Juan Salvo trapped in a time loop, the mystery is far from over.

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The Eternaut is now streaming on Netflix.

Also read: What does The Eternaut mean? Details from the Netflix sci-fi series, explored

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