The chance of a city-killing asteroid striking Earth is higher than scientists previously believed, according to a non-profit group of asteroid hunters led by an ex-astronaut.
A global network that listens for nuclear weapons detonations detected 26 asteroids that exploded in Earth’s atmosphere from 2000 to 2013, data collected by the Comprehensive Nuclear Test Ban Treaty Organisation shows. The explosions include the February 15, 2013 impact over Chelyabinsk, Russia, which left more than 1,000 people injured by flying glass and debris.
“There is a popular misconception that asteroid impacts are extraordinarily rare – that’s incorrect,” says former astronaut Ed Lu, who heads the California-based B612 Foundation. Asteroids as small as 40m – less than half the size of an American football field – have the potential to level a city, he adds. “Picture a large apartment building – moving at Mach 50,” Lu says.
Mach 50 is 50 times the speed of sound, or roughly 17km per second.