Video: Earth has had 26 powerful asteroid explosions in 13 years

By Deborah Netburn
April 22, 2014, 3:13 p.m.

Is asteroid impact a real threat to humanity? Watch this video and decide for yourself.
(VIDEO @ http://www.latimes.com/science/scien...,5822355.story )

What you see above is a visualization of 26 powerful explosions in the Earth's atmosphere that have occurred since the year 2000 -- each the result of a space rock slamming into our planet.

The video was put together by the B612 Foundation, a nonprofit that hopes to send a privately funded infrared telescope into space by 2018 to map the solar system, locating as many potentially dangerous asteroids as possible.

Most of us remain blissfully unaware of the pummeling the Earth gets on a regular basis because the force released by most asteroid impacts is absorbed entirely by our atmosphere and rarely causes much damage at ground level.

But we are not always so lucky. The asteroid that exploded over the Russian city of Chelyabinsk in February 2013 is a sobering reminder of the kind of damage a relatively small asteroid an estimated 65 feet in length can do.

The asteroid impacts included in the video above released anywhere from 1 kiloton to 600 kilotons of energy. (The bomb that flattened Hiroshima in 1945 released 15 kilotons of energy).

The asteroid explosions were recorded by the Nuclear Test Ban Treaty Organization, which has an array of infrasonic microphones scattered throughout the world. The microphones are used to monitor man-made nuclear explosions, but they also pick up nature-made asteroid explosions as well.

"As far as we know, all these explosions were asteroids, though it is possible some were small comets (but unlikely)," Peter Brown of the University of Western Ontario, who first reported the asteroid explosion data in a paper published in Nature last year, wrote via email. The video is based on information in his report.

Just how terrifying you find the video above, and the data it is based on, depends on your perspective.

"To me, all this data shows just how effective our atmosphere is at shielding us from these things that could cause a lot of damage," Brown said. "If you wait long enough, you will get rocks that punch through the atmosphere, but you have to wait a long time."

Ed Lu, a former NASA astronaut and the co-founder of the B612 Foundation, agreed that our atmosphere provides a powerful line of defense against asteroid impacts, but he'd like to see civilization do more to protect itself.

"I would say the other thing protecting us is our human brains and our judgment," he said, "and whether we use that judgment to do something about asteroids."

http://www.latimes.com/science/scien...,5822355.story