There are countless meteorites in our solar system. They are solid objects that enter the Earth's atmosphere at great speed. They are probably the debris of asteroids.
Meteorites range from a few millimeters to several kilometers in diameter. When they burn up in the atmosphere, they create a glowing trail, which we call a meteor or shooting star. Almost everyone has observed this phenomenon before. Between five and fifteen can be seen in the sky every hour.
Although meteorites seldom reach the surface of the Earth, they can create a crater when they do. Over one hundred of these impact craters are known on Earth. The Barringer crater in Arizona is among the best known. It is 1.3 kilometers in diameter and 174 meters deep! It is estimated to be about 25,000 years old. The largest meteorite crater on Earth formed the basin of the Noerdlinger Ries. It is approx. 15 million years old and has a diameter of 25 kilometers. It no longer looks very impressive, as it has been worn down by erosion.
Meteorites can be divided into two main groups according to their composition. There are rock meteorites, which are made up mainly of silicates, and iron meteorites that can be partially iron and nickel with small amounts of copper and cobalt. There is also a mixed type with rock and iron. Rock meteorites erode faster than others and are therefore recognized less often. However, identifications immediately after the sighting of the light trail have indicated that the majority of meteorites are made up of rock.
With its weight of 60 tons, the object found near Hoba West in Namibia is among the largest ever found. A meteorite of thirty tons and two smaller ones were found in Ahnighito in Greenland. They were made up of iron and had long provided the Eskimos with raw materials for making tools.
A 65-kilogram meteorite from Treysa in Germany is of special note. After it was sighted as a fireball on the 3rd of April 1916, the geophysicist Wegener precisely calculated its trajectory and impact position, thus making its recovery possible.
We speak of a meteorite shower when numerous meteors occur within a short time span. Some of these are the annually returning Lyrids, Perseids, Leonids and others. They are named after the constellation in which they appear in the sky.
