A type 4 radio burst, which typically lasts hours to days, lasted for nearly three weeks and likely came from a helmet stream in the sun's atmosphere. Researchers hope the finding will help improve space weather predictions
A radio burst from the sun detected in August 2025 initially appeared to NASA scientists to be a normal solar event. These bursts, caused by the interaction of energetic particles and the sun's magnetic field, typically last from a few hours to several days.
But this signal goes on and on.
Instead of fading quickly, the radio burst lasted an astonishing 19 days, a new record as the longest known event of its kind. The previous record was just five days.
Record-breaking Type 4 solar flare
The unusual event was classified as a Type 4 radio burst, a category associated with clouds of electrons trapped within large magnetic structures around the sun. The radio waves themselves are harmless to Earth, but the same magnetic conditions can also cause intense solar activity that can disrupt satellites and spacecraft.
Scientists are particularly interested in these eruptions because they can reveal conditions that lead to dangerous space weather.
To study the event, researchers collected observations from several spacecraft located throughout the inner solar system.
Spacecraft across the solar system joined the search
Because of the Sun's rotation, the long flare moved into the field of view of different spacecraft over time. Each mission observed the flare for several days during its 19-day existence, and scientists were able to combine the data to create a more complete timeline of the event.
The researchers also developed a new method using observations from the STEREO mission to determine the source of the outburst. Their analysis led to a massive magnetic structure in the sun's atmosphere called a helmet stream.
Scientists believe that three coronal mass ejections (CMEs) that erupted from the same region may have helped sustain the eruption for nearly three weeks. CMEs are massive explosions that launch vast amounts of plasma and magnetic energy into space.
The findings could improve space weather forecasting
The results may help researchers better detect and analyze long radio bursts from the Sun in the future.
A better understanding of these events could also strengthen space weather forecasting, helping scientists anticipate solar activity that could threaten satellites, spacecraft, and other technologies operating in space.
for the scientific article DOI: 10.3847/2041-8213/ae5537
Short FAQ:
What did NASA detect?
NASA has detected a solar radio burst that lasted 19 consecutive days, much longer than is typical for similar events.
Are radio waves dangerous to the Earth?
The radio waves themselves are harmless, but the magnetic conditions that create them can be related to solar activity that could affect satellites and spacecraft.
What is helmet current?
A helmet stream is a large, characteristically shaped structure in the solar atmosphere where magnetic fields can trap charged particles and produce radio emissions.
Why is the event important?
Understanding such events can improve space weather prediction, especially in cases where solar activity could disrupt technological systems in space.
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