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Science and the Planet: Tracing a Distant Radio Flash October 10, 2026 · 5:43 · With Maya and Nora
This is Science and the Planet, where we explain a science story and why it matters.
Transcript Maya You’re listening to Slow English FM. This is Science and the Planet, where we explain a science story and why it matters. I’m Maya, with Nora, our science and environment columnist. Thanks for listening. Maya Astronomers have identified the galaxy that sent out the most distant fast radio burst yet recorded. The signal traveled for more than 10 billion years before reaching Earth. Nora, what is a fast radio burst, and what did astronomers find? Nora A fast radio burst, or FRB, is a very brief flash of radio waves from space. These flashes last only milliseconds. NASA says astronomers used the James Webb Space Telescope to identify the galaxy that hosted one called FRB 20240304B. A host galaxy is the galaxy where the event happened. NASA describes this as the most distant FRB seen so far. Maya The burst was first detected in 2024. Did Webb detect the flash itself, or did it help answer a different question? Nora The MeerTRAP team first detected the burst on March 4, 2024, using the MeerKAT radio telescope in South Africa. Webb was used later to identify the host galaxy. So the two telescopes had different roles: MeerKAT detected the radio signal, and Webb helped astronomers locate its source galaxy. Maya How do astronomers connect a brief flash with a particular galaxy, especially when the flash comes from so far away? Nora In this case, NASA reports that astronomers used Webb to identify the galaxy linked to the burst. The galaxy is a small dwarf galaxy, and it is actively forming stars. The burst itself lasted only milliseconds, but astronomers could study the galaxy associated with it. That gives them a location in the distant universe to investigate, rather than only a flash with no identified host. Maya NASA gives a redshift measurement of 2.148. What does that tell us in plain language? Nora Redshift describes how light is stretched toward longer wavelengths as the universe expands. Astronomers can use that stretching to estimate how far away an object is and how long its light has traveled. NASA says this measurement places the burst about 3 billion years after the Big Bang. The signal then traveled for more than 10 billion years before reaching Earth. Maya That is a long journey for a flash that lasted milliseconds. The Guardian reports that it passed through about 80 percent of cosmic history. Is that another way of describing its age and distance? Nora It describes the long span of cosmic history the signal crossed on its way here. NASA reports the travel time as more than 10 billion years, while The Guardian describes the journey as passing through about 80 percent of cosmic history. Both details help show why this is an especially distant burst. They do not mean that the flash itself lasted for billions of years. The flash was extremely brief; its journey was extremely long. Maya The cause of these bursts is still uncertain. What do researchers know, and what remains open? Nora NASA says the origin of fast radio bursts remains uncertain. A 2020 report in The Guardian described evidence linking at least some bursts to magnetars. A magnetar is a type of neutron star with an especially strong magnetic field. That evidence concerns at least some bursts, not necessarily every burst. So it is useful context, but it does not settle what caused this particular signal. Maya Why study a radio flash if we still do not know exactly what causes it? Nora NASA says the signal carries information about matter and structures along its path. In simple terms, as the radio waves travel through the universe, they can reveal clues about material between the source and Earth. Researchers can use those clues to study matter that is otherwise hard to see. Identifying the host galaxy also gives them important context for interpreting the burst. The discovery therefore matters both for understanding the source and for using the signal as a probe of the distant universe. Maya So this discovery gives astronomers a distant source to study, but it does not solve the mystery of what creates every fast radio burst. Nora That’s right. It identifies the host galaxy of the most distant burst recorded so far, and it shows how radio telescopes and Webb can contribute different pieces of the picture. The physical cause remains uncertain, while the signal itself can offer clues about the universe it crossed. Maya That’s Science and the Planet. Thanks for listening to Slow English FM. Stay with us.
