Potentially Hazardous Asteroids and Comets

Potentially hazardous asteroids and comets or, more generally, potentially hazardous objects (PHOs) are defined to be near-Earth asteroids or comets (near-Earth objects [NEOs]) with orbits that come close to Earth. These potentially hazardous objects have the potential to cause significant human suffering unlike anything we have encountered in our history if Earth impact with a PHO did indeed occur. The population of NEOs with a diameter larger than one (1) kilometer is estimated to be 1,000 objects. The estimated population with diameters greater than 40 m is a 1,000 times (one million) greater. Overall, it is estimated that over one million NEOs exist that could cause damage to the Earth from impact. None yet has been found that poses an immediate threat. We must continue to be vigil, and current programs watching the heavens are presented.