A Comet May Have Exploded Over Chile 12,000 Years Ago —and it Could Happen Again

You wouldn’t want much to do with Chile’s Atacama Desert today. Officially designated the driest place in the world, it has an average annual rainfall of just 15 mm (0.6 in.). Some parts of the 103,000 sq. km (40,500 sq. mi) expanse get no rain at all. But 12,000 years ago, at the end of the Pleistocene era, things were different. Megafauna like sloths and early horses roamed what was then a grassland, and humans had begun to settle the area. Shifting trade winds and ocean currents eventually shut off the rain, but even before those terrestrial forces transformed the Atacama, a decidedly extraterrestrial one did too: at that same 12,000 year point, a great comet exploded over the region, turning a 75 km (45 m) stretch of land partly to green and black glass. At least that’s the conclusion of a new study published Nov. 2 in Geology, and if the researchers are right, there could be more such glassy scarring from more such comet hits elsewhere on Earth. [time-brightcove not-tgx=”true”] The glassy corridor just north of the Andes Mountains, discovered in 2012, was originally attributed to intense wildfires that burned away scrub and grasses and melted the underlying soil. Carbon dating fixed the time of the glass’ formation, but Peter Schultz, a planetary scientist at Brown University and lead author of the new paper, was not so sure about the rest of the scenario. The extent of the glass was greater than what wildfires would likely cause, and ...
Source: TIME: Science - Category: Science Authors: Tags: Uncategorized healthscienceclimate Space Source Type: news