ONE of the largest impact craters on Earth was probably caused by a comet strike rather than an asteroid. If so, the crater could have provided ideal conditions for life to flourish.
Susan Kieffer and her team at the University of Illinois in Urbana-Champaign compared the rock structure and composition in and around two of the world’s largest craters. The first, a 65-million-year-old crater at Chicxulub on the Yucatan peninsular in Mexico, is widely believed to be the site of the impact that wiped out the dinosaurs. The other crater, in Sudbury, Ontario, dates back to 1.8 billion years ago.…
