Expert stresses the importance of monitoring comets and asteroids that could pose a threat to Earth

Read MoreMost people observe comets with wonder and awe as they streak across the sky. But one man observes them with a more vigilant eye and warns us of the potential devastation they hold. Ian Lee reports.Most people observe comets with wonder and awe as they streak across the sky. But one man observes them with a more vigilant eye and warns us of the potential devastation they hold. Ian Lee reports.