The Farthest Radio Flash Ever Had a Hidden Return Address

For a few thousandths of a second, an apparently empty patch of sky blasted out radio waves. The source lies over 10 billion light-years from Earth, more than twice as far as the previous record holder for this kind of signal.

The event, cataloged as FRB 20240304B, belongs to a class of flashes called fast radio bursts, which astronomers have logged by the thousands. Because each one is over almost before it starts, what produces them remains unclear.

MeerKAT, a South African network of 64 radio dishes, caught this one and pinned down its exact position. The signal had smeared out heavily in transit, which told researchers it came from very far off. Powerful ground-based telescopes then examined the spot and found essentially nothing. The likeliest reason, the team said, was a host galaxy too dim for them to register.

The James Webb Space Telescope saw it. According to a study published Oct. 8 in Science, the galaxy is smaller than expected, busy churning out stars and metal-poor, holding little beyond hydrogen and helium. The burst dates to when the cosmos was roughly 3 billion years into its life, evidence that such flashes began early.

Researchers suggest a magnetar may be responsible. That is the intensely magnetized core a star leaves behind after exploding as a supernova. The galaxy's traits could hint at the kind of neighborhood that breeds these flashes. They do not settle the question.

Webb found the galaxy. Whether a magnetar fired the flash is an open question.

Read the full story at Live Science, October 8, 2026

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