Is the Earth Targeted for an Impact?

Not that the experts know of! None of the asteroids or comets discovered so far is on a collision course with Earth. However, they can't speak for those that are not yet discovered. In principle, one of those could hit any time, but statistically the chances are very small.

• Asteroid and Comet Impact Hazards  - NASA
• NASA Near Earth Object Program Office
• Near Earth Asteroid Tracking Home Page
• SpaceGuard UK
• Impact Hazard: A Systems Approach - White paper on public policy issues associated with the impact hazard, by C. Chapman, D. Durda & R. Gold (February 24, 2001)
• Dealing with the Impact Hazard - Comprehensive technical summary by David Morrison and colleagues of the asteroid impact hazard as of mid-2002.
• Earth Impact Effects Program (University of Arizona)

Torino Scale

The Torino Scale is a "Richter Scale" for categorizing the Earth impact hazard associated with newly discovered asteroids and comets. It is intended to serve as a communication tool for astronomers and the public to assess the seriousness of predictions of close encounters by asteroids and comets during the 21st century.