Halley's Comet provided more than just a light show for residents of planet Earth in the year 530 AD—a chunk of it may have slammed into Greenland, creating such a massive dust storm in the atmosphere that it triggered drought, famine, and possibly even the first recorded instance of the Black Death in Europe, reports LiveScience. The revelation comes courtesy of a new study out of Columbia that found all kinds of "extraterrestrial stuff" in samples of Greenland's ice core from that time.
"Of the two brightest apparitions of Comet Halley, one of them is in 530," says the lead researcher. "Comets are normally these dirty snowballs, but when they're breaking up or they're shedding lots of debris, then that outer layer of dark stuff goes away, and so the comet looks brighter." It adds up to circumstantial evidence that Halley triggered a cooling period of the Earth in subsequent years, one that made people more vulnerable to "Justinian's plague" recorded in 541-542, writes Mike Wall. (Read more Halley's Comet stories.)