Could asteroids bombard the Earth to cause a mass extinction in 10 million years?
(PHYSorg.com Space & Earth)

Scientists have spent decades debating whether asteroids and comets hit the Earth at regular intervals. At the same time, a few studies have found evidence that the large extinction events on Earth - such as the one that wiped out the dinosaurs 66m years ago - repeat themselves every 26m to 30m years. Given that there`s good evidence that an asteroid triggered the dinosaur extinction, it makes sense to ask whether showers of asteroids could be to blame for regular extinction events.