When researchers registered a Type IV solar radio burst in August 2025, it initially looked ordinary. Such signals usually last hours or a few days.
But this one did not stop. It ended after 19 days, far surpassing the previous record of five.
NASA traces the burst to a large structure in the solar atmosphere called a helmet streamer. A radio signal from the Sun lasting almost three weeks is a very long broadcast even for solar science.
In brief
It was a Type IV radio burst: electrons trapped by magnetic fields emit radio waves. Such signals normally last hours or days, not nearly three weeks.
Why it matters
At 19 days, the event lasted almost four times as long as the previous five-day record. The waves are harmless to people, but their magnetic environments can also produce space-weather events relevant to satellites and spacecraft.
A closer look
STEREO, Parker Solar Probe, Wind and Solar Orbiter observed the signal in succession as solar rotation carried its source into view. That narrowed the origin to a large helmet streamer.
More facts
Researchers suspect that three coronal mass ejections from the same region fuelled the exceptionally long event. The result appeared in Astrophysical Journal Letters and helps classify long-lived radio signals as indicators of space weather.
How we know
This story is based on a publicly available original source.
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