2009 DD45 rose above the Pacific Ocean to the west of Tahiti. Its small size was safe in a collision with our planet.
Timothy Spahr of the Minor Planet Center has quickly confirmed that the subject would be increased to 0.00047 astronomical units from the center of the Earth. Up to 60 meters in diameter, an asteroid enters the atmosphere at an angle of incidence too low, a few degrees, for example, failed to pass through the atmosphere and causes no harm.
It just bounces on the atmospheric layer of the Earth and goes back into space. This occurred August 10, 1972 in the skies over Montana in the northern United States. The chances of this happening is once every 200 years.
By cons, once every thousand years, an asteroid 75 meters in diameter hit the Earth causing a crater 1 700 meters in diameter.
An asteroid 350 meters in diameter would cause a crater 6 000 meters in diameter. The chances of this happening is once every 16 000 years.
Apophis, the asteroid 250 meters in diameter, could be the next threat. | It is currently estimated at one chance in 45 000 probability that this rock come crashing into the Pacific Ocean April 13, 2036. 
* The Meteor Crater in Arizona, measuring 1 500 m in diameter, it dates from 49 000 years. The estimated diameter of the meteorite is 75 meters. | 
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