Meteorites and asteroids
The interplanetary space is not empty!
|Updated June 01, 2013
The interplanetary space is far from empty, it is littered with dust and material dating from the creation of the solar system. The asteroids and comets, metallic and rocky objects, move at a dizzying pace around the planets and our Sun. Sometimes their orbits cross that of Earth or the Earth causing a collision, the energy released by the impact is terrifying. Meteorites and comets bombard our planet since the birth of the solar system. Although asteroids 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 cross our orbit are called geo cruisers. Astronomers have estimated the trajectories of asteroids likely to end millions of lives on our planet.
Apophis is a small asteroid as it 250 meters wide and could represent a threat. It is now estimated that one in 45 000 probability that the stone came crashing into the Pacific Ocean on 13 April 2036.
Video: Meteor Crater is an impact crater 170 m deep and 1.1 km in diameter. It is located in the State of Arizona in the western United States of America. Also known Barringer Crater in memory of the mining engineer Daniel Moreau Barringer. © delorayn1-YouTube
What is a meteorite?
A meteorite is a stony object or ferrous extra-terrestrial small that reaches the Earth's surface. If the asteroid is the celestial body in space, the meteorite is what remains when it crashed on the surface of a planet.
But most meteorites burn and break under the pressure of the atmosphere layer, as the Peekskill meteorite that fell in 1992, which could not withstand a force of pressure of 300 atmospheres. Depending on its size and internal structure, the meteorite may or may not cross the Earth's atmosphere. The impact crater is in theory, 24 times the size of meteor craters but some can reach about thirty times this size, when the car density is very high.
Image: The meteorite fell in 1906 Willamette Valley in Oregon, is on display at the Museum of Natural History in New York, AMNH/HAYDEN
How to recognize a meteorite?
The most striking detail of a meteorite is his weight. A meteorite or ferrous siderite, is often 2 to 3 times heavier than terrestrial rocks of similar size. The rocky or stony meteorites called lithoids are 2 times lighter than terrestrial rocks same volume.
Image: Ferrous meteorite found in Rancho Gomelia, Mexico. It is a octahedrite composed of an alloy of nickel and iron. The acid test revealing the structure itself is clearly visible Widmanstätten (size about 14 cm).
Images of meteorites
Image: A metal meteorite photographed on the planet Mars. Credit: NASA
Image: This piece of meteorite dark and smooth, 631g and a little less than 10 cm square, was found in Australia. Her present crustal signs of a merger and is almost entirely composed of pyroxene, a typical component of lava. By its internal structure grainy and abundance of isotopes of oxygen, this fragment bears no resemblance to terrestrial and lunar rocks. Its spectral signature is in fact identical to that of the crust of the asteroid Vesta. Most fragments are exposed to the Western Australian Museum.