Seattle - The Earth was struck by 26 asteroids ranging in explosive power from 1 to 600 kilotons of TNT between 2000 and 2013,says a private US foundation which is soliciting donations for a space mission to protect the planet from such impacts.
For comparison, the atomic bomb that destroyed the Japanese city of Hiroshima in 1945 had the power of 15 kilotons.
The impacts were monitored by a network of sensors operated by the international Nuclear Test Ban Treaty Organisation to detect nuclear detonations.
The Earth is continuously colliding with fragments of asteroids, the California-based B612 Foundation noted. It said that most of them exploded too high in the atmosphere to do serious damage on theground.
In addition to the 600-kiloton impact in Chelyabinsk, Russia, in 2013, there have been asteroid impacts greater than 20 kilotons in Indonesia, the Southern Ocean and Mediterranean Sea since the turn of the millennium.
"While most large asteroids with the potential to destroy an entire country or continent have been detected, fewer than 10,000 of the more than 1 million dangerous asteroids with the potential to destroy an entire major metropolitan area have been found by all existing space or terrestrially operated observatories," said former US astronaut Ed Lu, the B612 Foundation's CEO and co-founder.