Scientists say that during the mid-Holocene, the Sun experienced a mysterious magnetic ‘solar event’. Around 7,000 years ago, our planet was heavily ‘bombarded’ by a flux of intense cosmic rays.
Based on new analysis of ancient tree in California, scientists say an abnormal solar even occurred in sometime around 5480 B.C. as experts measured carbon-14 levels in tree rings.
Strangely, the exact cause of the mystery remains an enigma for scientists, but there are some who believe that it may have been triggered by our sun’s magnetic activity.
The team of experts, led by researchers at Nagoya University, analyzed carbon-14 levels in the bristlecone pine forest in California.
It is well-known that these trees can live for thousands of years, meaning that they are excellent keepers of solar events that directly affected our planet throughout history.
According to experts, as the sun’s activity weakened, a type of carbon referred to as carbon-14 increases in the atmosphere. These ‘cosmic’ changes are registered by trees, and evidence is found in tree rings which are able to absorb the carbon in the air.
According to AJ Timothy Jull of the University of Arizona:
“We measured the 14C levels in the pine sample at three different laboratories in Japan, the US, and Switzerland, to ensure the reliability of our results. We found a change in 14C that was more abrupt than any found previously, except for cosmic ray events in AD 775 and AD 994, and our use of annual data rather than data for each decade allowed us to pinpoint exactly when this occurred.”
To better understand the situation, scientists compared the data with other events that have occurred in the last couple of thousands of years.
Their results suggest the sun may have experienced an ‘unknown phase of grand solar minimum,’ when solar activity was EXTREMELY weak.
Another possibility is that the sun may have experienced strong solar bursts and fluctuations in solar magnetic activity.
However, scientists have yet to pin-point the exact cause. Experts hope that telescope observations of flares from other sun-like stars may help them understand what occurred with our sun thousands of years ago.
Fusa Miyake of Nagoya University said:
“Although this newly discovered event is more dramatic than others found to date, comparisons of the 14C data among them can help us to work out what happened to the sun at this time. We think that a change in the magnetic activity of the sun along with a series of strong solar bursts, or a very weak sun, may have caused the unusual tree ring data.”
The article “Large 14C excursion in 5480 BC indicates an abnormal sun in the mid-Holocene” was published in PNAS at: www.pnas.org/cgi/doi/10.1073/pnas.1613144114