Asteroid deflection. Artwork of rockets firing from the surface of a near-Earth asteroid. The rockets provide thrust which nudges the asteroid away from an Earth-bound trajectory. The power from the main engine of the Space Shuttle could, in theory, deflect a 1 kilometre asteroid given 30 years warning. Asteroids are minor planets with diameters of less than 100 kilometres. A collision with Earth would cause massive tsunamis if it hit the oceans and block sunlight due to the huge quantities of dust thrown in to the stratosphere. It is thought that the extinction of the dinosaurs around 65 million years ago was caused by an asteroid impact. An asteroid, comet or other large body posing a danger to Earth is known as a Near- Earth Object (NEO).