The Tortured History Of Earth's First 500 Million Years

New research suggests the Earth was pummelled by four gigantic asteroids measuring at least 600 miles across in its early days — impacts that would have rebooted the surface, boiled off the oceans, and extinguished any fledgling life. Here's what we now know about the Late Bombardment Era and its affect on our… » 7/31/14 1:15pm 7/31/14 1:15pm