potentially hazardous asteroid

A potentially hazardous asteroid (PHA) is an asteroid whose orbit brings it close to Earth and is large enough to cause significant damage if it were to impact the planet. These objects are typically larger than 200 meters (656 feet) in diameter and could strike Earth within the next century or two.1

Astronomers actively search for and track these asteroids to assess the risk of collision. While smaller objects like meteoroids burn up in the atmosphere, larger asteroids and comets pose a greater threat. An impact from a 1-kilometer (0.6-mile) asteroid could cause global climate disturbances, and an impact from a 10-kilometer (6-mile) object is believed to have caused mass extinctions, including that of the dinosaurs.21

Planetary defense programs, such as NASA's Planetary Defense Coordination Office, aim to detect dangerous asteroids and develop strategies to mitigate potential impacts. The Double Asteroid Redirection Test (DART) mission successfully demonstrated a method for deflecting an asteroid's orbit.3