Space rocks often enter the Earths atmosphere. But they usually explode and burn before falling to the ground. About 70 percent of our planet is covered with water. As a result, most meteorites falling from the sky disappear on the oceans floor. We would not know about them if it was not for an international agency.
You may remember the meteorite that exploded last year 23 kilometers above Chelyabinsk, in Russia. Scientists estimate it was about 18 meters long before it fell to Earth. They also think it had a mass of about 10,000 tons.
Many people would have died if the meteorite fell in a populated area. Luckily, it did not. Instead it broke apart mid-air and most of the pieces fell into Lake Chebarkul. But that is a little too close for some people.
The Comprehensive Nuclear-Test-Ban Treaty Preparatory Commission is a group based in Vienna, Austria. It says the Earth is visited by meteorites more often than we know.
The group records explosions made by meteorites that enter Earths atmosphere. Pierrick Mialle works for the commission, also known as the CTBTO. He is an acoustics expert, specializing in the study of sounds.
He says since meteorites are sometimes entering the atmosphere, they are creating loud air bursts.
The commission controls sensors and other equipment that watch for possible violations of the Nuclear Test ban treaty. Some of the devices are seismic, meaning they measure the movement of the Earth. Others are hydrostatic, meaning they measure the movement of the Earths water. The Commission also uses ultrasound and radioactivity sensors.
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