‘Impossible’ particle that hit Earth may have been dark matter
We may already have had our first-ever encounter with dark matter, according to researchers who say a mysteriously high-energy particle detected in 2023 is not a neutrino after all, but something far stranger
By Jonathan O’Callaghan
11 June 2025
A blazar may have blasted dark matter at Earth
M. Weiss/CfA/NASA
An extremely high-energy particle that was spotted tearing through Earth has left scientists flummoxed ever since it was discovered. While many researchers believe the particle was an unusual neutrino, some are now suggesting it may be something even wilder: a particle of dark matter travelling across the cosmos.
The KM3NeT detector, off the coast of Italy, spotted this “impossible” neutrino in 2023 while it was still under construction. The particle in question was of immense proportions, 35 times more energetic than any seen before. Where it came from remains a mystery, with possible sources including a galaxy with a very active central black hole known as a blazar, or a background source of high-energy neutrinos pervading the universe.
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Bhupal Dev at Washington University in St. Louis, Missouri, and his colleagues have another idea. They suggest the event might not have been a neutrino at all, but instead a dark matter particle crashing into our planet that originated from a blazar. “It opens up a new way you can really test dark matter,” he says. “We can convert these neutrino telescopes into dark matter detectors.”
Neutrino detectors already have a difficult job to do because these particles are extremely tiny and nearly massless, rarely interacting with matter as they traverse the cosmos. When they arrive at Earth, they can occasionally crash into atoms, producing a particle called a muon that can be picked up by neutrino detectors like KM3NeT and IceCube at the south pole.
IceCube has seen evidence for hundreds of cosmic neutrinos since 2011, but never something as energetic as KM3NeT’s discovery. That was confusing, because whatever source KM3NeT was seeing, IceCube should have seen it too.
