Tucson Standard

Researchers from the University of Arizona and ETH Zurich have used radiocarbon in tree-ring samples to study solar activity from 1000 B.C.E. to 2 B.C.E. This study provides a detailed record of solar behavior during the first millennium B.C.E.

The findings, published in Nature Communications, offer insights into the sun's historical influence and may help in predicting future solar events. Lead author Nicolas Brehm highlighted the detail these results provide on how the sun operated millennia ago, which is crucial for understanding the potential effects of solar outbursts and "magnetic storms" on technology.

The sun, a ball of hot gas with a magnetic field, undergoes an 11-year cycle influencing cosmic radiation reaching Earth. This affects radiocarbon levels, as explained by Charlotte Pearson, co-author and associate professor at the Laboratory for Tree-Ring Research. By studying these patterns, researchers can analyze solar activity annually.

The research is significant for understanding the stable 11-year solar cycle during a period known as the "Hallstatt plateau," where carbon-14 production was stable, making dating difficult. Brehm was intrigued by the consistency of this cycle during the first millennium B.C.E., while Pearson emphasized the importance of studying data between solar events.

Moreover, the observations have implications for archaeology, as solar patterns found in tree-rings worldwide can now accurately date wooden artifacts from the Hallstatt period. Pearson noted the importance of reproducible solar patterns for determining archaeological timelines.

A new radiocarbon analysis instrument at the Laboratory for Tree-Ring Research will enhance the ability to gather data from small wood samples, allowing the team to explore further the vast archive of tree-ring samples. Pearson expressed optimism about filling gaps in the radiocarbon record through this advanced technology.