Comet Hitting Earth | Universe Today

Written by Jerry Coffey

In the movie “Deep Impact” the chance of a comet hitting Earth is explored. The world is saved when a spacecraft is built to deliver a system of destroying the comet before an Extinction Level Event(ELE) could happen. Is this pure science fiction or is there a chance of a comet hitting Earth? The fact is that there are comets and other solar debris hitting the Earth on a yearly basis. The most recent was in 2008 when a small asteroid hit our atmosphere. It burned up immediately and left nothing to hit the ground, but it goes to show that these events happen on a yearly basis. The chances of an ELE are very rare and only happen many millions of years apart.

Small objects hit the Earth with an amazing regularity. Astronomers have even gone to the trouble to predict these comet hitting Earth events. Objects with a 1 km diameter impact the Earth every 500,000 years on average. Large collisions with five kilometer objects happen approximately once every ten million years. Objects with diameters of 5-10 m impact the Earth's atmosphere approximately once per year, but break up and most of the material is vaporized in the upper atmosphere. Objects of diameters of over 50 meters strike the Earth approximately once every thousand years. It is easy to believe these numbers when you take into account the millions of objects that are out there, then couple that with gravity anomalies, etc. The surprise is actually that you would expect more frequent impact events.

A comet hitting Earth helps us to learn many new things about solar objects, but could be very dangerous for the peoples of the world if we are caught off guard. The complexity of the SENTRY and NEAT programs will prevent any unexpected strikes and will help us to defend any threatened cities. The movies have embellished on what might happen to prevent an impact, but they might not be too far off from the truth.

NASA has a good article about monitoring near Earth objects here. Here on Universe Today there are two good articles on the topic. One is about meteors hitting the Earth and the other is about the Tunguska event being caused by a comet hitting Earth. Astronomy Cast offers a good episode about destruction in our solar system.

Filed under: Astronomy

Tags: comet, comet hitting Earth, Comets, Solar System