Medieval "Dark Eclipse" Helps Date Ice Cores — and Time Volcanic Eruptions

"You never know where an astronomical event might turn up in old historical records, and how it might link up with evidence from modern science. Researchers at the University of Geneva recently uncovered such an astronomical tale from the archives, using contemporary accounts of a curiously dark lunar eclipse to give insight into volcanic eruptions and their effect medieval climate. The researchers, who published their study April 21st in Scientific Reports, were examining ice cores from Greenland and Antarctica over the past couple millennia, looking for sulfate spikes that would indicate volcanic eruptions. ..."
Sky and Telescope