NASA: National Aeronautics and Space Administration


Ask an Astrobiologist
"Hello, I was wondering when a comet was due to pass Earth again? When will the next few be? "
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  1. Question

    How would an asteroid effect our planet or moon?

    The only way an asteroid could have much influence on the Earth is if it collided with us. Small asteroids pass close to the Earth quite often, but these events, while they sometimes generate newspaper stories, have no influence on the Earth. Only if it hits will there be consequences. Any asteroid larger than about 100m in diameter will create an explosion larger than that of the biggest nuclear bombs, and collision with an asteroid 2 km or larger could disrupt the environment and lead to the end of modern civilization. Asteroids can also carry water to the Earth, and this process may have been important when the Earth's oceans formed billions of years ago, but collision with an asteroid today is unlikely to have any benefits for our planet. Asteroids also strike the Moon, but such impacts have no influence on Earth. For more information about asteroid impacts, see the NASA impact hazard website.

    David Morrison
    NAI Senior Scientist

    January 13, 2004