Drawing illustrating air showers from high-energy cosmic rays, which were unexpectedly discovered in 1912.Researchers have discovered a puzzling surplus of high-energy electrons bombarding Earth from space. The source is unknown, but it must be close to the solar system and could be made of dark matter.
"This is a big discovery," says John Wefel of Louisiana State University. "It's the first time we've seen a discrete source of accelerated cosmic rays standing out from the general galactic background."
Galactic cosmic rays are subatomic particles accelerated to almost light speed by distant supernova explosions and other violent events, according to an explanation from NASA. They swarm through the Milky Way, forming a haze of high-energy particles that enter the solar system from all directions.
Wefel likens the bombardment to driving down a freeway among family sedans, mini-vans and trucks—when suddenly a bunch of Lamborghinis bursts through the normal traffic. "You don't expect to see so many race cars on the road—or so many high-energy electrons in the mix of cosmic rays," he says. Seventy electrons may not sound like a great number, but like seventy Lamborghinis on the freeway, it's a significant surplus.
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