The interplanetary space is far from empty, it is littered with dust and material dating from the creation of the solar system. Asteroids and comets, metal and rock, traveling at a tremendous pace around the planets and our Sun. Sometimes their orbits intersect that of a planet or the Earth causing a collision. Meteorites and comets pounded the planet since the birth of the solar system. Although they seem quietly installed on their orbits between Mars and Jupiter, they are sometimes destructive and they must likely the emergence of life on Earth. The asteroids are our closest neighbors, they are in one way or another, linked to our destiny. Those who operate near the Earth and that cross our orbit are called Near Earth Objects (ECA), the Earth-Crossing Asteroids English.
On Monday, March 2, 2009 at 13:44 UTC, the asteroid 2009 DD45 passed very close to 63 500 km of the Earth, which corresponds to 0.00048 AU (Symbol: UA) The mean distance from Earth to the Sun. a AU is 149,597,871 km. It is a unit often used for distances in the solar system, or the distance between two stars in a dual system. .
It was discovered Feb. 27, 2009, by Rob McNaught of the Siding Spring Observatory, Australia, when he was approximately 1.6 million kilometers from Earth.
The mean diameter of the object has been estimated at 19 meters + or - 4 meters. The near-Earth asteroid 2008 TC3 burned in the atmosphere above Africa 7 October 2008 at 02h46 UTC without causing damage.
This asteroid two to five meters in diameter, was the first asteroid tracking in space before its fall to Earth.
Image: picture of artist.
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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.
Image: 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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