Asteroids are small rocky bodies that orbit the sun and can be covered in dust. Their total mass in the solar system is approximately 1/35 that of the moon, and they range in size from 10 meters to 100 kilometers. It is believed that an asteroid impact 65 million years ago created the Chicxulub crater and contributed to the extinction of the dinosaurs. Proposed methods for deflecting potentially hazardous asteroids include direct nuclear explosions, laser sublimation, electric propulsion, using gravity to alter an asteroid's trajectory, and deploying solar sails.