10 facts about meteorites – rocks that have fallen to the ground from the sky.
Have you ever seen meteorites falling? Probably not. This is because the “stars” that fall from the sky are called “meteors” (from Ancient Greek means “raised from the ground, hanging, lofty”). If a “star” is very bright, it is called “bolide”. A meteorite is something that fell down on Earth, on the other planet or on large celestial body (well, it is even harder to find them there, than on Earth, but still it is possible).
Information about all meteorites found is recorded in a special database kept by the Meteoritical Society – the international organization dealing with the study of meteorites. As of March 13, 2018, it contains information about some 66,000 meteorites. Innovation House offers to take this database as a travel guide in search of meteorites.
Hoba iron meteorite (see photo above) – world’s largest one (at least, of those that have been found). It fell on the territory of present-day Namibia about 80,000 years ago and was found in 1920 by the owner of a nearby farm Hoba West Farm, from which the meteorite and got its name.
At that time, it weighted about 66 tons, but erosion, vandals and scientists made it “loose” 6 tons. Hoba is a tabloid body of metal (84%), measuring 2.7×2.7×0.9 metres. Remaining portion of meteorite is nickel with traces of cobalt.
In 1955, Hoba was declared to be a national monument attracting numerous foreign tourists.
A total of 43 meteorites were found in Ukraine: Sukhoj Liman, Genichesk, Kharkov, Odessa, Bjelaja Zerkov – meteorites that were named after inhabited localities, near which they fell, or they were found. The “oldest” Ukrainian meteorite – Owrucz has fallen in 1775. The “newest” one is Verkhnyi Saltov. No one knows when exactly it has fallen on Earth, but it was discovered in 2001 in Kharkiv oblast close to the village having the same name, when archaeological excavations of Verkhii Saltiv Archaeological Complex (the capital city of Khazar Khaganate was located there in VIII-X centuries) were performed. This is a an iron meteorite weighing 9.5 kilograms and measuring 21x16x7 cm.
Knyahinya meteorite fell in the summer of 1866 close to Knyahinya village in Zakarpattia. Its total weight exceeds 500 kg.
Knyahinya is a meteoric stone, the largest meteorite found on the territory of Ukraine. In summer 1866 at an altitude of about 40 kilometers bolide exploded and broke into some 1,200 pieces. This has happened close to Knyahinya village located in Zakarpattia. The largest piece of this meteorite weighing almost 280 kilograms has split to almost equal parts from the fall. The total weight of Knyahinya exceeds 500 kg. It is believed that some pieces of this meteorite may still be found near the fall area.
There are 7 meteorite craters in Ukraine as well. They are also named “astroblemes”. The largest of them – Boltysh is about 25 kilometers in diameter and is located on the boundaries of Kirovohrad and Cherkasy oblasts. It is believed that it was formed nearly 65 million years ago – roughly at the same time, when famous Chicxulub crater (sometimes associated with the extinction of dinosaurs) was formed. Meteoritic craters also exist in Vinnytsya, Volyn, Dnipropetrovsk, Zhytomyr, Poltava, and Cherkasy oblasts.
Meteor Crater is about 1,200 meters in diameter.
Craters in the world
So far, a total of 190 meteorite craters were discovered. However, it is thought that there should be more of them, since it is believed that meteorite falls every 1-3 million years resulting in a crater of at least 20 kilometers in diameter.
Vredefort crater is the largest crater on Earth. It is located in the Republic of South Africa and is more than 300 kilometers in diameter. There is also Wilkes Land crater located under the ice cap of Antarctica. Its diameter is about 500 kilometers, but it is not yet known whether it is of meteorite nature.
All known meteorite craters were formed in prehistoric times. Tswaing, the youngest astrobleme, is about 220,000 years old. It is also located in South Africa.
The name Tswaing means “place of salt” in Tswana language
Hailed from Mars
Earth has some meteorites that were once a part of Mars. These meteorites are rare and so far there are 201 known meteorites only. For a fragment of Mars hit the Earth, some space body shall first fall on the ground of the Red Planet and “beat out” some rocks from it.
Nakhla is one of the most famous Martian meteorites. It fell in Egypt in 1911. It exploded in the atmosphere and broke into pieces weighting from 20g to 1.8kg. There is a legend: supposedly, one of the fragments hit the dog vaporizing the animal instantly. Surprisingly enough, but this legend was long thought to be true, but no facts of evidence were provided.
It makes sense that Martian meteorites (though not only they) are being studied in search for signs of life. Various organic compounds were found in Nakhla, but it was not enough to draw a conclusion as to the existence of life on Mars.
In 1996, another Martian meteorite, ALH 84001, was the subject of much controversy when researchers at NASA found a sort of fossilized bacteria in it. However, this finding may also have different explanations and does not prove at all that there is or there were any life on the Red Planet.
The surface of a fragment of the Martian meteorite Nahla (enlarged). Bacteria may create similar structures in Earth-like conditions.
Found on Mars
Meteorites from Mars should not be confused with meteorites found on Mars. Currently, there are six of them. According to the Meteoritical Society, the first of them was found in 2006 by Opportunity Mars Exploration Rover on Meridiani Planum and for that very reason it was called Meridiani Planum. Curiosity Rover discovered another five iron meteorites in 2014-2017.
One of the landscapes of Martian Meridiani Planum – the place where the meteorite was found
In addition to Mars, meteorites were also found on the surface of Moon. In 1969 astronauts of Apollo 12 have found Bench Crater meteorite, and in 1971 the team of Apollo 15 have found Hadley Rille.
However, the meteorites from Moon also hit our planet. The database contains information about 330 of such “aliens”. The largest of them is called Northwest Africa 10309 and weights 16.5 kg.
Most of meteorites on Earth were found in Antarctica – 42,638 items, i.e. almost two thirds of all known meteorites. This is attributable to the fact that they are clearly noticeable there, and therefore ANSMET (ANtarctic Search for METeorites) established by NASA and National Science Foundation is dealing with the search of such meteorites.
“Industrial” search of meteorites in Antarctica
Tunguska meteoroid impact
Witnesses of this phenomenon describe it as a ball of fire followed by extraordinarily powerful explosion in the sky. Fortunately, this region is scarcely populated, and so no one was hurt, but flattened 2,000 square kilometers.
Fallen trees in Tunguska ereignis zone. Photo taken in 1929.
More than a hundred hypotheses were developed at different times as to explain the Tunguska ereignis. Most of them have no scientific evidences or have some evidences of fantastic nature. There are some serious doubts that this was a meteorite, since neither meteorite nor the crater were found. One of the possible explanation states that this was a burst of a part of a comet that, as you probably already know, mostly consists of ice, and that is why nothing or at least nothing big hit the Earth.