By Earth’s most famous killer asteroid came from the outer reaches of the solar system, researchers report in the Aug. 16 Science.
About 66 million years ago, an asteroid slammed into the sea just off Mexico’s Yucatán Peninsula, forming the Chicxulub crater. That powerful impact may have triggered a mass extinction event on Earth, killing off more than 60 percent of the planet’s species, including all nonbird dinosaurs (SN: 1/25/17). The impact left geochemical fingerprints, such as elevated levels of the element iridium, in a thin layer of rock found in multiple countries around the globe (SN: 9/8/84).
