Models allow us to simulate events rather than make them happen in reality. This is desirable in many ways. It may be too costly or damaging to actuate an event, and models allow us to investigate many 'what if' scenarios. In this case, the asteroid collision with the Earth happened many millions of years ago, and the effects of the asteroid's impact have long passed. When the asteroid impacted, we would have expected major local, regional and even global impacts, and by understanding how the Earth works, computer models can allow us to make an informed prediction of the effects of the impact.
