Asteroid impact prediction
Videos
Asteroid impact prediction is the prediction of the dates and times of asteroids impacting Earth, along with the locations and severities of the impacts.
One of the 7,000 buildings damaged by the 2013 Chelyabinsk meteor
Viewed from space by WISE using a thermal camera, asteroid 2010 AB78 appears redder than the background stars as it emits most of its light at longer infrared wavelengths. In visible light it is very faint and difficult to see.
Ground based telescopes can only detect objects approaching on the night-side of the planet, away from the Sun. Roughly half of impacts occur on the day-side of the planet.
Near-Earth object
Videos
A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun (perihelion) is less than 1.3 times the Earth–Sun distance. This definition applies to the object's orbit around the Sun, rather than its current position, thus an object with such an orbit is considered an NEO even at times when it is far from making a close approach of Earth. If an NEO's orbit crosses the Earth's orbit, and the object is larger than 140 meters (460 ft) across, it is considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids, but about 0.35% are comets.
Image: Asteroid 2006DP14
Image: The VLT images the very faint Near Earth Object 2009 FD
Image: Comet Hartley 2