Activity event

Scientists spot event of ‘extreme’ solar activity by examining tree rings


  • SEP events can be determined by dating tree rings
  • When these events hit the atmosphere, they create a chain reaction
  • This reaction creates carbon-14

Researchers in a recent study found evidence of another event of extreme solar activity by examining tree rings.

The sun is constantly emitting energetic particles, the Astronomical Geophysical Union (AGU) noted in a press release, noting that some of these particles eventually reach Earth.

In fact, extreme solar energetic particle (SEP) events can be determined via dendrochronological recording, or dating of tree ringsbecause when SEPs hit the atmosphere, they create a chain reaction that creates carbon-14, AGU said.

“So far, three extreme MS events have been reported as a rapid increase in 14C in tree rings and increases in 10 Be and 36 Cl in ice cores,” the study researchers explain, published in Geophysical Research Letters, writes.

These were events in 660 BCE, 774-775 CE, and 992-993 CE, and are said to be “much more important” than such events in the space age.

In their study, the researchers described a fourth extreme MS event between 5411 BC.

The event occurred during a solar maximum and caused atmospheric carbon-14 to rise 0.6% in the northern hemisphere. It then stayed that way for a few years before returning to normal levels, AGU explained. According to the researchers, carbon-14 during this event was similar to the three previously known events, but was slightly lower than the 992-993 CE event.

While it is possible that the measurements reflect another cause, such as a nearby supernova explosion, if it turns out to be an SEP event, it could help predict future events since the the sun’s energy flow is the basis of everything space weather.

As the AGU noted, a “key unresolved question” is how often the sun emits such particles strong enough to affect or even destroy space electronics like satellites.

“Although the cause of the event’s signal has just been hypothetical, it is consistent with the origin of the extreme MS event based on the similarity to other confirmed MS events,” the researchers wrote. “If this event stems from MS, this finding will help better estimate the frequency and intensity of extreme MS events and their relationship to solar activity.”

Representation. Photo: Manfred Antranias Zimmer / Pixabay

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