The B612 Foundation (which attempts to build public support for defenses against killer asteroids) has released a report claiming that asteroids with nuclear bomb level of explosive force hit the Earth's atmosphere every year.
...between 2000 and 2013 some 26 explosions on Earth ranging in energy from 1 to 600 kilotons were caused by asteroids.
To put that in perspective, the Little Boy nuclear bomb dropped on Hiroshima had 16 kilotons of explosive force (or possibly 15 kt with the Nagasaki bomb at about 21 kt..
The Earth is continuously colliding with fragments of asteroids, the largest in recent times exploding over Tunguska, Siberia in 1908 with an energy impact of 5-15 megatons. More recently, we witnessed the 600-kiloton impact in Chelyabinsk, Russia in 2013, and asteroid impacts greater than 20 kilotons occurred in South Sulawesi, Indonesia in 2009, in the Southern Ocean in 2004, and in the Mediterranean Sea in 2002. Important to note as well is the fact that none of these asteroids were detected or tracked in advance by any existing space-based or terrestrial observatory.
But luckily the asteroid above Chelyabinsk exploded at about 18 miles (29.7 km) high. By contrast, the 1908 Tunguska event asteroid exploded at about 5-10 km and had a similar or larger size than the Chelyabinsk asteroid.
The B612 folks say the recent asteroids exploded too high up in the atmosphere to cause damage. Watch their video:
Count me in with the people who say we ought to build asteroid defenses.
|Share |||Randall Parker, 2014 April 23 08:42 PM|