Centuries-old aurora sightings help scientists reconstruct 8 solar cycles

Centuries-old reports of strange lights in the night sky have helped scientists reconstruct a missing chapter in the Sun’s history. A study published in Scientific Reports by Kristof Petrovay, Laura G. Magyar and Hisashi Hayakawa has reconstructed eight solar activity cycles between 1560 and 1640 using historical records of aurorae, offering a way to trace solar behaviour from an era when systematic telescopic observations were only beginning.When the sky became a record of the SunBefore telescopes began producing regular observations of sunspots, scientists had few direct ways to determine how active the Sun was. One of the clues available to researchers today comes from historical accounts of aurorae, the glowing displays that occur when energetic particles associated with solar activity interact with Earth’s atmosphere.But aurora records are an imperfect proxy.