NASA APOD – Are asteroids dangerous? Some are, but the likelihood of a dangerous asteroid striking the Earth during any given year is low. Because some past massΒ extinction events have been linked to asteroid impacts, however, humanity has made it a priority to find and catalog thoseΒ asteroidsΒ that may one day affectΒ life on Earth.Β Pictured hereΒ are the orbits of the over 1,000 knownΒ Potentially HazardousΒ Asteroids (PHAs). These documented tumblingΒ bouldersΒ of rock and ice are over 140 meters across and will pass within 7.5 million kilometers of Earth — about 20 times the distance to the Moon. Although none of them willΒ strike the EarthΒ in the next 100 years —Β not all PHAs have been discovered, and past 100 years, many orbits become hard to predict. Were an asteroid of this size toΒ impact the Earth, it could raiseΒ dangerous tsunamis, for example. To investigate Earth-saving strategies, NASA’sΒ Double Asteroid Redirection TestΒ (DART) is planned for launch later this year. Of course rocks and ice bits of much smaller sizeΒ strike the Earth every day, usually pose no danger, and sometimes creatingΒ memorable fireballΒ andΒ meteor displays.

Orbits of Potentially Hazardous Asteroids
Image Credit: NASA, JPL-Caltech

Source: APOD: 2021 August 29 – Orbits of Potentially Hazardous Asteroids (

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.