Solar cycles during the seventeenth century revealed by equatorial aurora records

Solar cycles are fundamental to astrophysics, space exploration, technological infrastructure, and Earth's climate. A better understanding of these cycles and their history can aid in risk mitigation on Earth, while also deepening our knowledge of stellar physics and solar system dynamics. Determining the solar cycles between 1600 and 1700 — especially the post-1645 Maunder Minimum, characterized by significantly reduced solar activity — poses challenges to existing solar activity proxies. This study utilizes a new red equatorial auroral catalog from ancient Korean texts to establish solar cycle patterns from 1623 to 1700. Remarkably, a further reevaluation of the solar cycles between 1610 and 1755 identified a total of 13 cycles, diverging from the widely accepted record of 12 cycles during that time. This research enhances our understanding of historical solar activity, and underscores the importance of integrating diverse historical sources into modern analyses.