Originating in the outer space, an object reaches Earth and gets a place in the list of meteorites. There have been many instances of extraterrestrial bodies impacting the Earth's surface while some have only passed through the Earth's atmosphere before they were destroyed. Meteorites have been arousing interest of the masses as there is an element of mystery that surrounds them. Where do they originate? What makes some of them enter the Earth's atmosphere? How dangerous can they get?
Space research and astronomy have revealed some interesting information about some of these questions and researched thoroughly on the different types of meteorites. Most of the meteorites disintegrate before reaching Earth while some reach the planet's surface. Huge meteorites form craters on Earth while the smaller ones involve less danger.
▸ Meteorites containing small round particles are known as chondrites and form about 86% of those falling on Earth.
▸ Those similar in appearance to small igneous rocks are called achondrites and believed to be the crustal material of asteroids.
▸ Meteorites originating from the core of asteroids are known as iron meteorites and form about 5% of the meteorites that fall.
History has recorded several instances of meteorites impacting the Earth. Some of them are mentioned here.
ALH 84001: It was found in the Allan Hills, Antarctica in December 1984. Meteorite hunters of the United States working on ASMNET project discovered this meteorite. When discovered, its mass was 1.93 kilograms and its rock was reportedly one of the oldest forms. This meteorite was supposed to have come from Mars. Later, it was believed to consist of some traces of the life on Mars and this made ALH 84001 all the more famous.
Hoba: This meteorite lies on the farm Hoba West in Namibia and has never been moved elsewhere because of its exceptionally greater mass. With a mass of about 60 tons, it is the largest meteorite known to mankind. It is tabloid in shape and composed of metal. It is believed to have landed on Earth about 80,000 years ago. In 1955, it was declared as a national monument and has since then been attracting visitors from different parts of the world.
Tunguska Event: The Tunguska explosion took place in June 1908 near Tunguska River, now a part of Russia. Most probably, the air burst of a large meteorite caused this explosion. The energy emitted from this explosion was about 1000 times greater than that of the bomb blast of Hiroshima. According to the eyewitnesses of this explosion, the event started with a flash of bright blue light and a sound originating from east and moving northward. Later, the sound was accompanied by shock waves that broke windows miles away. This was one of the famous disintegrating meteorites that find a place on the list of world's most famous meteorites.
Willamette Meteorite: This is an iron-nickel meteorite that was discovered in the United States near Oregon. It is the largest of the meteorites found in the United Sates as also the sixth-largest in the world. Probably, the meteorite had landed in the region, which is now known as Canada. This meteorite weighing about 15.5 tons is one of the very large meteorites in the world.
Orgueil: This meteorite fell in France in 1864 and is a relatively older meteorite. The fall of this meteorite consisted of small stones that covered a massive area. This is one of those eight meteorites that belong to the CL chondrite group. A striking feature of this type of meteorite it that its composition is similar to that of the Sun. This meteorite is one of the most researched ones. For purposes of deeper study of the composition of this meteorite, it was split into pieces. Currently, it exists in the form of pieces kept in different museums in Europe and the United States.
Murchison: With a mass greater than 100 kilograms, it happens to be among the most-studied meteorites in the world. It fell in the town of Murchison, Victoria on September 28, 1969. It broke into three fragments, then disappeared, leaving smoke, following which vibrations were felt. Classified as a carbonaceous chondrite, it is known for being rich in organic compounds.
Sylacauga: Classified as a chondrite, this meteorite fell in Alabama on November 30, 1954. It is also known as the Hodges meteorite because a part of it had injured Ann Elizabeth Hodges. Interestingly, it is the first documented extraterrestrial object that injured a human being in America. It is said to have broken into three pieces; namely, the Hodges fragment, the McKinney fragment (that Julius McKinney, an African-American farmer found), and another fragment which fell near Childersburg.
Campo del Cielo: It is a group of iron meteorites that belong to the class of octahedrites. It is also the name of the area northwest of Buenos Aires in Argentina, which was where the meteorites were found. It translates to 'Field of the Sky'. The area still has fragments of an iron meteorite. The ones that have been recovered so far constitute a mass of over 100 tons. This makes Campo de Cielo, the heaviest meteorite recorded on Earth. Its largest fragment weighing 37 tons is second to the Hoba meteorite. The craters created by this meteorite span an area of 3x20 kms and are believed to be about 5000 years old. After many expeditions to trace the mass of iron in the craters, the samples were found to contain 90% iron and 10% nickel. It was concluded that the craters were formed because of meteorites falling in the region.
Canyon Diablo: Classified as an iron octahedrite, Canyon Diablo meteorites are fragments of the asteroid which created the Barringer Crater in Arizona, USA. The asteroid fell around 50,000 years ago and is believed to have been known to the prehistoric native Americans. Many fragments of this meteorite are famous, the biggest one being the Holsinger Meteorite weighing 639 kilograms. Its 485-kg fragment is the largest one outside the United States. The meteorite is named after Canyon Diablo, a canyon in Arizona that lies a few miles away from the crater.
These were some of the famous meteorites. They have always been a subject of interest for researchers around the world.