Korean scientists have discovered a strange solar anomaly. 350 years ago. How is that even possible?

The sun changes its activity in the so-called solar cycles. Each such cycle – as we know today – lasts on average 11 years, during which our star goes from minimum to maximum and back to the minimum of its activity. Solar activity can be predicted, among others: after observations of sunspots and the frequency of strong aurora borealis.

Korean scientists predicted an unusual anomaly. Hundreds of years ago

However, between 1645 and 1715 a strange anomaly occurred, today known as the Maunder Minimum. At that time, the Sun was surprisingly inactive, and astronomers observed surprisingly few sunspots, much fewer than in the first half of the 17th century and after. Interestingly, the coldest period occurred during the same period, a time of significant cooling in some places on Earth (it is still unclear whether these two anomalies are related).

from Korean royal chronicles indicates that something else has changed. While examining the documents, scientists came across calculations regarding the frequency of aurora occurrences during the Maunder Minimum. Based on this data, modern scientists managed to estimate that at that time the Sun completed each complete cycle not in 11, but on average in 8 years. This is a gigantic change that is an anomaly that is still incomprehensible.

It is not clear whether, based on these records, astronomers of the time could have been aware of the occurrence of solar cycles and their shortening during the anomalies. For Europeans, the existence of cycles was discovered only by the German astronomer Samuel Heinrich Schwabe in 1844, and the first full cycle was observed and described only in the second half of the 19th century. Scientists believe that Korean notes from the 17th and 18th centuries will help us today understand the causes of the Maunder Minimum.