Ancient Trees Reveal 800-Year-Old Solar Storm

Why this is here: The study identified a potential intense aurora caused by extreme solar activity as described in a Japanese diary entry from February 1204.

Scientists at the Okinawa Institute of Science and Technology investigated a historical “red sky” event in Japan. They combined historical records with carbon-14 analysis from ancient trees to reconstruct an extreme solar radiation event from the early 13th century.

The research team examined asunaro trees buried in northern Japan. They found unusual spikes of carbon-14 in the wood’s growth rings.

These carbon-14 increases likely resulted from high-energy particles from the sun hitting Earth’s atmosphere. Researchers also consulted Japanese and Chinese historical texts, including the “Meigetsuki” diary. The diarist, Fujiwara no Teika, noted red lights in the sky near Kyoto in February 1204.

The team determined the sun experienced more intense activity between the 12th and 13th centuries. Current solar cycles last about 11 years, but the analyzed period showed cycles of seven to eight years. Understanding past solar behavior may help predict future space weather risks to satellites and astronauts.