What is a meteor and meteorite in brief? School encyclopedia

They can be large and small, inconspicuous and terrifying, iron and silicate, the most diverse. The scientific name for a shooting star is meteorite. This definition applies to bodies larger than 10 microns. Smaller space guests are called micrometeorites.

What are meteorites?

Almost 93% of meteorites are stony. Among them there are chondrites consisting of silicate spheres (ordinary, carbonaceous and enstatine), and achondrites that have undergone melting and the accompanying differentiation in composition into silicates and metals. The remaining bodies are divided into iron-stone (pallasites and mesosiderites) and pure iron.

It is important to note that a meteorite is not a meteor. These concepts mean different things. A meteorite is the body itself, and a meteor is the fiery trail formed in the atmosphere during its fall. It is he who is mistaken for a “shooting star” on which romantically minded individuals make wishes.

Meteorites can vary in size. Some of them are as small as a grain of sand, others reach tens of tons. Representatives scientific world claim that during the year 21 tons of extraterrestrial bodies fall on our planet, while representatives of the stream can weigh from a few grams to 1000 kilograms.

The largest meteorites in Earth's history

Sutter Mill fell to Earth on April 22, 2012. Its path ran over Nevada and California, and its speed exceeded 29 kilometers per second. Parts broke off from the meteorite over these states different sizes, the main part reached Washington and exploded right above it. The force of the explosion was equal to 4000 tons. Scientists know the age heavenly wanderer- more than 4500 million years.

In Peru, near and near the Bolivian border, there was a fall in 2007 cosmic body, fragments of which were not found. What happened is evidenced only by a pit 6 meters deep and 30 meters in diameter, filled muddy water. At the time of the incident, according to local residents, water boiled like a fountain. There is a version that there were toxic substances, since after his fall, eyewitnesses began to experience severe migraines.

In June 1998, on the 20th, a space guest weighing 820 kg landed on a cotton field near the Turkmen city of Kunya-Urgench. The diameter of the funnel was about 5 meters. The International Meteor Society calculated the age of the body - more than 4 billion years - and recognized it as the largest of all that fell in the CIS, and the third largest in the world.

On a May night in 1990, from the 17th to the 18th, a 315-kilogram meteorite fell twenty kilometers from Sterlitamak. This event occurred on a state farm field, in the soil of which a 10-meter crater formed. At the same time, the cosmic body itself was immersed 12 m deep into the earth.

The Namibian meteorite is considered the largest found. This iron miracle is named Goba and has a volume of 9 cubic meters and weight 66 tons. Its fall occurred 80,000 years ago, but this ingot was discovered only in 1920. Now it is a local landmark.

Meteors are particles of interplanetary material that pass through the Earth's atmosphere and become incandescently heated by friction. These objects are called meteoroids and speed through space, becoming meteors. In a few seconds they cross the sky, creating luminous trails.

Meteor showers
Scientists estimate that 44 tons of meteorite material falls to Earth every day. Several meteors per hour can usually be seen on any given night. Sometimes the number increases sharply - these phenomena are called meteor showers. Some occur annually or at regular intervals when the Earth passes through a trail of dusty debris left behind by a comet.

Leonids meteor shower

Meteor showers are typically named after the star or constellation that is closest to where the meteors appear in the sky. Perhaps the most famous are the Perseids, which appear on August 12 each year. Each Perseid meteor is a tiny piece of Comet Swift-Tuttle, which takes 135 years to orbit the Sun.

Other meteor showers and associated comets are the Leonids (Tempel-Tuttle), the Aquarids and Orionids (Halley), and the Taurids (Encke). Most of the comet dust in meteor showers burns up in the atmosphere before reaching the Earth's surface. Some of this dust is captured by airplanes and analyzed in NASA laboratories.

Meteorites
Pieces of rock and metal from asteroids and other cosmic bodies that survive their journey through the atmosphere and fall to earth are called meteorites. Most meteorites found on Earth are pebbly, fist-sized, but some are larger than buildings. Once upon a time, the Earth experienced many serious meteorite attacks that caused significant destruction.

One of the best-preserved craters is the Barringer meteorite crater in Arizona, about 1 km (0.6 mi) in diameter, created by the fall of a piece of iron-nickel metal approximately 50 meters (164 ft) in diameter. It is 50,000 years old and so well preserved that it is used to study meteorite impacts. Since the site was recognized as such an impact crater in 1920, about 170 craters have been found on Earth.

Barringer Meteor Crater

A severe asteroid impact 65 million years ago that created the 300-kilometer-wide (180-mile) Chicxulub crater on the Yucatan Peninsula contributed to the extinction of about 75 percent of marine and land animals on Earth at the time, including dinosaurs.

There is little documented evidence of meteorite damage or death. In the first famous case An extraterrestrial object injured a person in the USA. Ann Hodges of Sylacauga, Alabama, was injured after a 3.6 kilogram (8 lb) rock meteorite struck the roof of her home in November 1954.

Meteorites can look like rocks on Earth, but they usually have a burnt surface. This burnt crust appears as a result of the meteorite melting due to friction as it passes through the atmosphere. There are three main types of meteorites: silvery, stony and stony-silver. Although most meteorites that fall to Earth are rocky, more meteorites are found in Lately– silver. These heavy objects are easier to distinguish from Earth's rocks than stony meteorites.

This image of a meteorite was taken by the Opportunity rover in September 2010.

Meteorites also fall on other bodies solar system. Mars rover Opportunity studied meteorites different types on another planet when he discovered a basketball-sized iron-nickel meteorite on Mars in 2005, and then found a much larger and heavier iron-nickel meteorite in 2009 in the same area. In total, the Opportunity rover discovered six meteorites during its journey to Mars.

Sources of meteorites
More than 50,000 meteorites have been found on Earth. Of these, 99.8% came from the Asteroid Belt. Evidence for their asteroid origin includes the meteorite's impact orbit calculated from photographic observations and projected back onto the asteroid belt. Analysis of several classes of meteorites showed a coincidence with some classes of asteroids and they also have an age of 4.5 to 4.6 billion years.

Researchers have discovered a new meteorite in Antarctica

However, we can only match one group of meteorites to a specific type of asteroid - eucrite, diogenite and howardite. These igneous meteorites originate from the third largest asteroid, Vesta. Asteroids and meteorites that fall to Earth are not parts of a planet that has broken up, but are composed of the original materials from which the planets formed. The study of meteorites tells us about the conditions and processes during the formation and early history of the solar system, such as age and composition solids, nature organic matter, the temperatures reached on the surface and inside the asteroids and the form into which these materials were reduced by the impact.

The remaining 0.2 percent of meteorites can be divided roughly equally between meteorites from Mars and the Moon. More than 60 known Martian meteorites have been ejected from Mars in meteor showers. They are all igneous rocks that crystallized from magma. The stones are very similar to earthly ones, with some distinctive features, which indicate a Martian origin. Almost 80 lunar meteorites are similar in mineralogy and composition moon rocks from the Apollo mission, but different enough to show they came from different parts of the Moon. Studies of lunar and Martian meteorites complement studies of lunar rocks from the Apollo mission and robotic exploration of Mars.

Types of meteorites
Often a common person imagining what a meteorite looks like, he thinks about iron. And it's easy to explain. Iron meteorites are dense, very heavy, and often take on unusual, and even spectacular, shapes as they fall and melt through our planet's atmosphere. And although most people associate iron with the typical composition of space rocks, iron meteorites are one of the three main types of meteorites. And they are quite rare compared to stony meteorites, especially the most common group of them, single chondrites.

Three main types of meteorites
Exists a large number of types of meteorites, divided into three main groups: iron, stony, stony-iron. Almost all meteorites contain extraterrestrial nickel and iron. Those that contain no iron at all are so rare that even if we asked for help identifying possible space rocks, we likely wouldn't find anything that didn't contain large amounts of the metal. The classification of meteorites is, in fact, based on the amount of iron contained in the sample.

Example of an iron meteorite

For most samples of this group, the iron component is approximately 90%-95%, the rest is nickel and trace elements. Iron meteorites are divided into classes based on chemical composition and structure. Structural classes are determined by studying two components of iron-nickel alloys: kamacite and taenite.

These alloys have a complex crystalline structure known as the Widmanstätten structure, named after Count Alois von Widmanstätten who described the phenomenon in the 19th century. This lattice-like structure is very beautiful and can be easily seen if iron meteorite cut into plates, polish and then pickle in a weak solution of nitric acid. In kamacite crystals discovered during this process, the average width of the bands is measured, and the resulting figure is used to divide iron meteorites into structural classes. Iron with a fine stripe (less than 1 mm) is called “fine-structured octahedrite”, with a wide stripe “coarse octahedrite”.

Stone meteorites
The largest group of meteorites are stony ones, which formed from the outer crust of a planet or asteroid. Many stony meteorites, especially those found on the surface of our planet for a long time, are very similar to ordinary earthly rocks, and it takes an experienced eye to find such a meteorite in the field. Recently fallen stones are characterized by a black, shiny surface that results from the surface burning in flight, and the vast majority of stones contain enough iron to be attracted to a powerful magnet.

A typical representative of chondrites

Some stony meteorites contain small, colorful, grain-like inclusions known as "chondrules." These tiny grains originated from the solar nebula, therefore, even before the formation of our planet and the entire Solar System, which makes them the oldest known matter available for study. Stony meteorites containing these chondrules are called "chondrites".

Space rocks without chondrules are called "achondrites." These are volcanic rocks formed volcanic activity on their “parent” space objects, where melting and recrystallization erased all traces of ancient chondrules. Achondrites contain little or no iron, making it more difficult to find than other meteorites, although specimens are often coated with a glossy crust that looks like enamel paint.

Stone meteorites from the Moon and Mars
Can we really find Moon and Martian rocks on the surface of our own planet? The answer is yes, but they are extremely rare. More than one hundred thousand lunar and approximately thirty Martian meteorites have been discovered on Earth, all of which belong to the achondrite group.

Lunar meteorite

The collision of the surface of the Moon and Mars with other meteorites threw fragments into open space and some of them fell to Earth. From a financial point of view, lunar and Martian samples are among the most expensive meteorites. In collector's markets, their price reaches thousands of dollars per gram, making them several times more expensive than if they were made of gold.

Stony-iron meteorites
The least common of the three main types is stony-iron, accounting for less than 2% of all known meteorites. They consist of approximately equal parts of iron-nickel and stone, and are divided into two classes: pallasite and mesosiderite. Stony-iron meteorites formed at the boundary of the crust and mantle of their “parent” bodies.

Example of a stony-iron meteorite

Pallasites are perhaps the most alluring of all meteorites and are definitely of great interest to private collectors. Pallasite consists of an iron-nickel matrix filled with olivine crystals. When olivine crystals are pure enough to display an emerald green color, they are known as gem perodot. Pallasites got their name in honor of the German zoologist Peter Pallas, who described the Russian Krasnoyarsk meteorite, found near the capital of Siberia in the 18th century. When a pallasite crystal is cut into slabs and polished, it becomes translucent, giving it an ethereal beauty.

Mesosiderites are the smaller of the two lithic-iron groups. They are composed of iron-nickel and silicates, and are usually attractive in appearance. The high contrast of the silver and black matrix, if the plate is cut and sanded, and random inclusions, leads to very unusual looking. The word mesosiderite comes from the Greek for "half" and "iron" and they are very rare. In thousands of official catalogs of meteorites, there are less than a hundred mesosiderites.

Classification of meteorites
The classification of meteorites is a complex and technical subject and the above is intended only as a guide. brief overview Topics. Classification methods have changed several times over the years last years; known meteorites were reclassified into another class.

Martian meteorites
A Martian meteorite is a rare type of meteorite that came from the planet Mars. Until November 2009, more than 24,000 meteors had been found on Earth, but only 34 of them were from Mars. Martian origin meteors were known by the composition of the isotopic gas, which is contained in meteors in microscopic quantities; an analysis of the Martian atmosphere was carried out by the Viking spacecraft.

The emergence of the Martian meteorite Nakhla
In 1911, the first Martian meteorite, called Nakhla, was found in the Egyptian desert. The occurrence and belonging of the meteorite to Mars was established much later. And they established its age - 1.3 billion years. These stones appeared in space after large asteroids fell on Mars or during massive volcanic eruptions. The force of the explosion was such that the ejected pieces of rock acquired the speed necessary to overcome the gravity of the planet Mars and leave its orbit (5 km/s). Nowadays, up to 500 kg of Martian rocks fall to Earth in one year.

Two parts of the Nakhla meteorite

In August 1996, the journal Science published an article about a study of the ALH 84001 meteorite, found in Antarctica in 1984. Started new job, is centered around a meteorite discovered in a glacier in Antarctica. The study was carried out using a scanning electron microscope, they identified "biogenic structures" inside the meteor that theoretically had the potential to be formed by life on Mars.

The isotopic date demonstrated that the meteor appeared about 4.5 billion years ago, and having entered interplanetary space, fell to Earth 13 thousand years ago.

"Biogenic structures" discovered on a meteorite section

By studying the meteor using an electron microscope, experts found microscopic fossils that suggested bacterial colonies consisting of individual parts volume approximately 100 nm. Traces of drugs produced during the decomposition of microorganisms were also found. Proof of a Martian meteor requires microscopic examination and special chemical analyses. A specialist can attest to the Martian occurrence of a meteor based on the presence of minerals, oxides, phosphates of calcium, silicon and iron sulfide.

The known specimens are invaluable finds because they represent typical time capsules from Mars' geological past. Data Martian meteorites we got it without any space missions.

The most large meteorites that fell to Earth
From time to time, cosmic bodies fall to Earth... more and less, made of stone or metal. Some of them are no larger than a grain of sand, others weigh several hundred kilograms or even tons. Scientists at the Astrophysical Institute of Ottawa (Canada) claim that several hundred solid alien bodies with a total mass of more than 21 tons visit our planet every year. The weight of most meteorites does not exceed a few grams, but there are also those that weigh several hundred kilograms or even tons.

The places where meteorites fall are either fenced off or, on the contrary, opened for public viewing so that everyone can touch the extraterrestrial “guest”.

Some people confuse comets and meteorites due to the fact that both of these celestial bodies have a fiery shell. In ancient times, people considered comets and meteorites to be a bad omen. People tried to avoid the places where meteorites fell, considering them a cursed zone. Fortunately, nowadays, similar cases is no longer observed, but on the contrary - the places where meteorites fall are of great interest to the inhabitants of the planet.

Let's remember the 10 largest meteorites that fell on our planet.

The meteorite fell on our planet on April 22, 2012, the speed of the fireball was 29 km/sec. Flying over the states of California and Nevada, the meteorite scattered its burning fragments over tens of kilometers and exploded in the sky over the US capital. The power of the explosion is relatively small - 4 kilotons (in TNT equivalent). For comparison, the explosion of the famous Chelyabinsk meteorite had a power of 300 kilotons of TNT.

According to scientists, the Sutter Mill meteorite was formed at the birth of our solar system, a cosmic body more than 4566.57 million years ago.

On February 11, 2012, hundreds of tiny meteorite stones flew over the territory of the People's Republic of China and fell over an area of ​​over 100 km in southern regions China. The largest of them weighed about 12.6 kg. According to scientists, the meteorites came from the asteroid belt between Jupiter and Mars.

On September 15, 2007, a meteorite fell near Lake Titicaca (Peru) near the Bolivian border. According to eyewitnesses, the event was preceded by loud noise. Then they saw a body engulfed in fire falling. The meteorite left a bright trail in the sky and a stream of smoke, which was visible several hours after the fireball fell.

A huge crater, 30 meters in diameter and 6 meters deep, formed at the crash site. The meteorite contained toxic substances, as people living nearby began to have headaches.

Stone meteorites most often fall to Earth (92% of total number), consisting of silicates. The Chelyabinsk meteorite is an exception; it was iron.

The meteorite fell on June 20, 1998 near the Turkmen city of Kunya-Urgench, hence its name. Before the fall, local residents saw a bright flash. The most most of The car weighs 820 kg, this piece fell into a field and formed a 5-meter crater.

According to geologists, the age of this celestial body is about 4 billion years. The Kunya-Urgench meteorite is certified by the International Meteorite Society and is considered the largest of all fireballs that fell in the CIS and third world countries.

The Sterlitamak iron fireball, whose weight was more than 300 kg, fell on May 17, 1990 on a state farm field west of the city of Sterlitamak. When the celestial body fell, a crater of 10 meters was formed.

Initially, small metal fragments were discovered, but a year later scientists managed to extract the largest fragment of the meteorite weighing 315 kg. Currently, the meteorite is in the Museum of Ethnography and Archeology of the Ufa Scientific Center.

This event took place in March 1976 in Jilin province in eastern China. The largest meteor shower lasted more than half an hour. Cosmic bodies fell at a speed of 12 km per second.

Only a few months later, about a hundred meteorites were found, the largest - Jilin (Girin), weighed 1.7 tons.

This meteorite fell on February 12, 1947. Far East in the city of Sikhote-Alin. The bolide was fragmented in the atmosphere into small iron pieces, which scattered over an area of ​​15 sq. km.

Several dozen craters with a depth of 1-6 meters and a diameter of 7 to 30 meters were formed. Geologists have collected several tens of tons of meteorite matter.

Goba meteorite (1920)

Meet Goba - one of the largest meteorites found! It fell to Earth 80 thousand years ago, but was found in 1920. A real giant made of iron weighed about 66 tons and had a volume of 9 cubic meters. Who knows what myths the people living at that time associated the fall of this meteorite with.

Composition of the meteorite. This celestial body is 80% iron and is considered the heaviest of all meteorites that have ever fallen on our planet. Scientists took samples, but did not transport the entire meteorite. Today it is located at the crash site. This is one of the largest pieces of iron on Earth extraterrestrial origin. The meteorite is constantly decreasing: erosion, vandalism and Scientific research did their job: the meteor dropped by 10%.

A special fence was created around it and now Goba is known throughout the planet, many tourists come to it.

The Mystery of the Tunguska Meteor (1908)

The most famous Russian meteorite. In the summer of 1908, a huge fire ball. The meteorite exploded at an altitude of 10 km above the taiga. The blast wave circled the Earth twice and was recorded by all observatories.

The power of the explosion is simply monstrous and is estimated at 50 megatons. Flight space giant- hundreds of kilometers per second. Weight, according to various estimates, varies - from 100 thousand to one million tons!

Fortunately, no one was hurt. A meteorite exploded over the taiga. In nearby populated areas the window was broken by the blast wave.

Trees fell as a result of the explosion. Forest area of ​​2,000 sq. turned into rubble. The blast wave killed animals within a radius of more than 40 km. For several days, artifacts were observed over the territory of central Siberia - luminous clouds and a glow in the sky. According to scientists, this was caused inert gases, which were released when the meteorite entered the Earth's atmosphere.

What was it? The meteorite would have left a huge crater at the crash site, at least 500 meters deep. Not a single expedition has been able to find anything like this...

The Tunguska meteor, on the one hand, is a well-studied phenomenon, on the other, one of the biggest mysteries. The celestial body exploded in the air, the pieces burned up in the atmosphere, and there were no remains left on Earth.

The working name “Tunguska meteorite” appeared because it is the simplest and most clear explanation a flying burning ball causing an explosion effect. The Tunguska meteorite was also called crashed alien ship, and a natural anomaly, and a gas explosion. What it was in reality, one can only guess and build hypotheses.

Meteor shower in the USA (1833)

November 13, 1833 in the USA over eastern territory there was a meteor shower. The duration of the meteor shower is 10 hours! During this time, about 240 thousand small and medium-sized meteorites fell on the surface of our planet. The meteor shower of 1833 is the most powerful meteor shower known.

Every day, dozens of meteorite showers fly near our planet. About 50 potentially dangerous comets are known that can cross the Earth's orbit. Collisions of our planet with small (not capable of causing much harm) cosmic bodies occur once every 10-15 years. A particular danger for our planet is the fall of an asteroid.

Chelyabinsk meteorite
Almost two years have passed since the residents of the South Urals witnessed a cosmic cataclysm - the fall of the Chelyabinsk meteorite, which became the first modern history an incident that caused significant harm to the local population.

The asteroid fell in 2013, on February 15. At first, it seemed to the South Urals that an “obscure object” had exploded; many saw strange lightning lighting up the sky. This is the conclusion reached by scientists who studied this incident for a year.

Meteorite Data
A fairly ordinary comet fell in an area near Chelyabinsk. Falls space objects It is precisely this nature that happens once in a century. Although, according to other sources, they happen repeatedly, on average up to 5 times every 100 years. According to scientists, comets with a size of about 10 m fly into the atmosphere of our Earth approximately once a year, which is 2 times larger than the Chelyabinsk meteorite, but this often happens over regions with a small population or over the oceans. Moreover, comets burn up and collapse at great heights, without causing any damage.

Trail from Chelyabinsk meteorite in the sky

Before the fall, the mass of the Chelyabinsk aerolite was from 7 to 13 thousand tons, and its parameters supposedly reached 19.8 m. After analyzing, scientists found out that only about 0.05% of the initial mass fell to the surface of the earth, that’s 4-6 tons. Currently collected from given quantity a little more than one ton, including one of the large fragments of aerolite weighing 654 kg, raised from the bottom of Chebarkul Lake.

A study of the Chelyabinsk maetorite based on geochemical parameters revealed that it belongs to the type of ordinary chondrites of class LL5. This is the most common subgroup of stony meteorites. All currently discovered meteorites, about 90%, are chondrites. They got their name due to the presence of chondrules in them - spherical fused formations with a diameter of 1 mm.

Indications from infrasound stations indicate that at the minute of strong braking of the Chelyabinsk aerolite, when approximately 90 km remained to the ground, a powerful explosion force equal to the TNT equivalent of 470-570 kilotons, which is 20-30 times stronger atomic explosion in Hiroshima, however, in terms of explosive power it is inferior to the fall of the Tunguska meteorite (approximately from 10 to 50 megatons) by more than 10 times.

The fall of the Chelyabinsk meteorite immediately created a sensation both in time and place. In modern history, this space object is the first meteorite to fall into such a densely populated area, resulting in significant damage. So, during the meteorite explosion, the windows of more than 7 thousand houses were broken, more than one and a half thousand people appealed for medical care, of which 112 were hospitalized.

In addition to significant damage, the meteorite also caused positive results. This event is the best documented event to date. In addition, one video camera filmed the phase of the fall of one of the large fragments of the asteroid into Lake Chebarkul.

Where did the Chelyabinsk meteorite come from?
For scientists, this question was not particularly difficult. It emerged from our solar system's main asteroid belt, a zone in the middle of the orbits of Jupiter and Mars where the paths of most small bodies lie. The orbits of some of them, for example, the asteroids of the Aten or Apollo group, are elongated and can pass through the orbit of the Earth.

Astronomers were able to quite accurately determine the flight trajectory of the Chelyabinsk resident, thanks to many photo and video recordings, as well as satellite photographs that captured the fall. Then astronomers continued the meteorite's path to reverse side, for the atmosphere, in order to build the complete orbit of this object.

Dimensions of fragments of the Chelyabinsk meteorite

Several groups of astronomers tried to determine the path of the Chelyabinsk meteorite before it hit the Earth. According to their calculations, it can be seen that the semimajor axis of the orbit of the fallen meteorite was approximately 1.76 AU. ( astronomical unit), This average radius earth's orbit; the point of the orbit closest to the Sun - perihelion, was at a distance of 0.74 AU, and the point most distant from the Sun - aphelion, or apohelion, was at 2.6 AU.

These figures allowed scientists to try to find the Chelyabinsk meteorite in astronomical catalogs of already identified small space objects. It is clear that most of the previously identified asteroids, after some time, “fall out of sight” again, and then some of the “lost” ones manage to be “discovered” a second time. Astronomers did not reject this option, that the fallen meteorite may be the “lost one.”

Relatives of the Chelyabinsk meteorite
Although complete similarities were not revealed during the search, astronomers still found a number of probable “relatives” of the asteroid from Chelyabinsk. Scientists from Spain Raul and Carlos de la Fluente Marcos, having calculated all the variations in the orbits of the “Chelyabinsk”, found its supposed forefather - asteroid 2011 EO40. In their opinion, the Chelyabinsk meteorite broke away from it for about 20-40 thousand years.

Another team (Astronomical Institute of the Academy of Sciences of the Czech Republic) led by Jiri Borovička, having calculated the glide path of the Chelyabinsk meteorite, found that it is very similar to the orbit of asteroid 86039 (1999 NC43) with a size of 2.2 km. For example, the semimajor axis of the orbit of both objects is 1.72 and 1.75 AU, and the perihelion distance is 0.738 and 0.74.

Difficult life path
Based on the fragments of the Chelyabinsk meteorite that fell to the surface of the earth, scientists “determined” its life history. It turns out that the Chelyabinsk meteorite is the same age as our solar system. When studying the proportions of uranium and lead isotopes, it was found that it is approximately 4.45 billion years old.

A fragment of the Chelyabinsk meteorite discovered on Lake Chebarkul

on his difficult biography indicate dark threads in the thickness of the meteorite. They arose when substances that got inside as a result of a strong impact melted. This shows that approximately 290 million years ago this asteroid survived powerful collision with some kind of space object.

According to scientists from the Institute of Geochemistry and analytical chemistry them. Vernadsky RAS, the collision took approximately several minutes. This is indicated by leaks of iron nuclei that did not have time to completely melt.

At the same time, scientists from the Institute of Geology and Mineralogy SB RAS (Institute of Geology and Mineralogy) do not reject the fact that traces of melting may have appeared due to the excessive proximity of the cosmic body to the Sun.

Meteor showers
Several times a year, meteor showers light up the clear night sky like stars. But they actually have nothing to do with the stars. These small cosmic particles of meteorites are literally celestial trash.

Meteoroid, meteor or meteorite?
Whenever a meteoroid enters the Earth's atmosphere, it generates a flash of light called a meteor or "shooting star." High temperatures caused by friction between the meteor and gas in the Earth's atmosphere heat the meteorite to the point where it glows. This is the same glow that makes a meteor visible from the surface of the Earth.

Meteors usually glow for a very short period of time - they tend to burn up completely before hitting the Earth's surface. If a meteor does not disintegrate as it passes through the Earth's atmosphere and falls to the surface, then it is known as a meteorite. The meteorites are believed to come from the Asteroid Belt, although some pieces of debris have been identified as coming from the Moon and Mars.

What are meteor showers?
Sometimes meteors fall in huge showers known as meteor showers. Meteor showers occur when a comet approaches the Sun and leaves debris behind in the form of “breadcrumbs.” When the orbits of the Earth and a comet intersect, a meteor shower hits the Earth.

So the meteors that form a meteor shower move on a parallel path and at the same speed, so for observers they come from the same point in the sky. This point is known as the "radiant". By convention, meteor showers, especially regular ones, are named after the constellation from which they come.

In addition to the planets, many other celestial bodies move around the Sun, the sizes of which are sometimes only 5-10 km. They often find themselves in the path of the Earth. Flying into our planet from high speed, they are warming up. In this case, we see meteors flying across the sky. Rocks that fall to Earth are called meteorites. They always fell to Earth. Their fall was described by ancient scientists and Chinese chroniclers, Slavic monks and. New research methods have shown that some of the stone meteorites found fell on our planet over 10 thousand years ago.

The fall of meteorites is accompanied by the appearance in the sky fireballs- fireballs. These are meteorites with a shell of hot objects surrounding them. The bolide sweeps across the sky, illuminating the area for tens and even hundreds of kilometers.

Meteorites, attracted to the Earth, are heated by friction with the air as they pass through the atmosphere. Some of them burn out before reaching the Earth. The larger the meteors, the less their atmosphere slows them down and the faster they fall to the ground. But such meteorites, fortunately, rarely fall. The only strong meteorite fall with an explosion that occurred in human memory happened in 1908 Podkamennaya Tunguska. As it later turned out, fiery body fell among the nomads engaged in hunting and reindeer herding. Fires broke out in many places, huts shook and shook, glass flew out of windows, plaster fell off the ceilings. All this was accompanied by a deafening roar, heard over a radius of thousands of kilometers.

Meteorites have also been found in other countries.

METEORITE - a piece of extraterrestrial matter that fell to the surface of the Earth; literally – “stone from the sky.” Meteorites are the oldest known minerals (4.5 billion years old), so they should preserve traces of the processes that accompanied the formation of the planets. Until samples of lunar soil were brought to Earth, meteorites remained the only samples of extraterrestrial matter. Geologists, chemists, physicists and metallurgists have been collecting and studying meteorites for more than 200 years. From these studies the science of meteorites emerged. Although the first reports of meteorite falls appeared a long time ago, scientists were very skeptical about them. Various facts led them to finally believe in the existence of meteorites. In 1800–1803, several famous European chemists reported that the chemical composition of "meteor rocks" from different impact sites was similar, but different from the composition of earthly rocks. Finally, when in 1803 a terrible “rain of stones” broke out in Aigle (France), littering the ground with fragments and witnessed by many excited eyewitnesses, the French Academy of Sciences was forced to agree that these were indeed “stones from the sky.” Now it is believed that meteorites are fragments of asteroids and comets. Meteorites are divided into “fallen” and “found”. If a person saw a meteorite fall through the atmosphere and then actually found it on the ground (a rare event), then such a meteorite is called a "fallen". If it was found by chance and identified, which is typical for iron meteorites, then it is called “found.” Meteorites are named after the places where they were found. In some cases, not one, but several fragments are found. For example, after the 1912 meteor shower in Holbrook (Arizona), more than 20 thousand fragments were collected. Meteorite falls. Until a meteorite reaches the Earth, it is called a meteoroid. Meteoroids fly into the atmosphere at speeds from 11 to 30 km/s. At an altitude of about 100 km, due to friction with the air, the meteoroid begins to heat up; its surface becomes hot, and a layer several millimeters thick melts and evaporates. At this time it is visible as a bright meteor (see METEOR). The molten and evaporated substance is continuously carried away by air pressure - this is called ablation. Sometimes, under the pressure of air, a meteor is crushed into many fragments. Passing through the atmosphere, it loses from 10 to 90% of its initial mass. However, the interior of the meteor usually remains cold, since it does not have time to warm up during the 10 seconds that the fall lasts. Overcoming air resistance, small meteorites significantly reduce their flight speed by the time they hit the ground and usually go deeper into the ground by no more than a meter, and sometimes they simply remain on the surface. Large meteorites are slowed down only slightly and upon impact produce an explosion with the formation of a crater, such as in Arizona or on the Moon. The largest meteorite found is the iron meteorite Goba (South Africa), whose weight is estimated at 60 tons. It was never moved from the place where it was found. Every year, several meteorites are picked up immediately after their observed fall. In addition, more and more old meteorites are being discovered. In two places in the east of the state. In New Mexico, where the wind constantly blows away the soil, 90 meteorites were found. Hundreds of meteorites have been discovered on the surface of evaporating glaciers in Antarctica. Recently fallen meteorites covered with a vitrified sintered crust, which is darker than the inside. Meteorites represent a large scientific interest; Most major natural science museums and many universities have meteorite experts.

Plan:

Introduction

• 1 Terminology
• 2 The process of meteorites falling to Earth
• 3 Classification of meteorites
  • 3.1 Classification by composition
  • 3.2 Classification by detection method
• 4 Traces of extraterrestrial organics in meteorites
  • 4.1 Coal complex
  • 4.2 "Organized Elements"
• 5 Large modern meteorites discovered in Russia
• 6 Interesting Facts
• 7 Individual meteorites
Notes

Introduction

Willamette meteorite

Goba is the largest meteorite found. It is also the largest naturally occurring piece of iron on Earth.

Meteorite- body cosmic origin, fallen onto the surface of a large celestial object.

Most meteorites found weigh between a few grams and several kilograms. The largest meteorite found is Goba (which was estimated to weigh about 60 tons). It is believed that 5-6 tons of meteorites fall to the Earth per day, or 2 thousand tons per year.

The existence of meteorites was not recognized by leading academics of the 18th century, and hypotheses of extraterrestrial origin were considered pseudoscientific. It is alleged that the Paris Academy of Sciences in 1790 decided not to consider future reports of rocks falling to the Earth as an impossible phenomenon. In many museums, meteorites were removed from collections so as not to “make museums a laughing stock.”

The Russian Academy of Sciences now has a special committee that supervises the collection, study and storage of meteorites. The committee has a large meteorite collection.

Academicians V.I. Vernadsky, A.E. Fersman, well-known meteorite research enthusiasts P.L. Dravert, L.A. Kulik and many others were involved in the study of meteorites.

1. Terminology

A cosmic body before entering the Earth's atmosphere is called a meteoroid and is classified according to astronomical criteria. For example it could be cosmic dust, meteoroid, asteroid, their fragments, or other meteoroids.

A celestial body flying through the Earth's atmosphere and leaving a bright luminous trail in it, regardless of whether it flies through the upper layers of the atmosphere and goes back into space, whether it burns up in the atmosphere or falls to Earth, can be called either a meteor or a fireball. Meteors are considered bodies no brighter than 4th magnitude, and fireballs - brighter than 4th magnitude, or bodies whose angular dimensions are distinguishable.

A solid body of cosmic origin that fell to the surface of the Earth is called a meteorite.

At the crash site large meteorite a crater (astrobleme) may form. One of the most famous craters in the world - Arizona. It is assumed that the largest meteorite crater on Earth - Wilkes Earth Crater (diameter about 500 km).

Other names for meteorites: aerolites, siderolites, uranolites, meteorolites, baituloi, sky, air, atmospheric or meteor stones, etc.

Phenomena similar to the fall of a meteorite on other planets and celestial bodies usually referred to simply as collisions between celestial bodies.

2. The process of meteorites falling to Earth

The meteor body enters the Earth's atmosphere at speeds from 11 to 72 km/s. At this speed, it begins to warm up and glow. Due to ablation (burning and blowing away by the oncoming flow of particles of the meteoroid body), the mass of the body reaching the surface may be less, and in some cases significantly less than its mass at the entrance to the atmosphere. For example, a small body that enters the Earth's atmosphere at a speed of 25 km/s or more burns up almost completely. At such a speed of entry into the atmosphere, out of tens and hundreds of tons of initial mass, only a few kilograms or even grams of matter reach the surface. Traces of the combustion of a meteoroid in the atmosphere can be found along almost the entire trajectory of its fall.

If the meteor body does not burn up in the atmosphere, then as it slows down it loses the horizontal component of its speed. This results in a change in the trajectory of the fall from, often, almost horizontal at the beginning to almost vertical at the end. As it slows down, the glow of the meteorite decreases and it cools down (they often indicate that the meteorite was warm and not hot when it fell).

In addition, the meteorite body may break into fragments, which leads to meteor showers.

“Regular” round (not elongated) traces from meteorites are explained by explosive processes accompanying its fall at high speed.

3. Classification of meteorites

3.1. Classification by composition

• stone
  • chondrites
    • carbonaceous chondrites
    • ordinary chondrites
    • enstatite chondrites
  • achondrites
• iron-stone
  • palasites
  • mesosiderites
• iron

The most common meteorites are stony meteorites (92.8% of falls). They consist mainly of silicates: olivines (Fe, Mg)2SiO4 (from fayalite Fe2SiO4 to forsterite Mg2SiO4) and pyroxenes (Fe, Mg)SiO3 (from ferrosilite FeSiO3 to enstatite MgSiO3).

The vast majority of stony meteorites (92.3% stony, 85.7% total number falls) - chondrites. They are called chondrites because they contain chondrules - spherical or elliptical formations of predominantly silicate composition. Most chondrules are no more than 1 mm in diameter, but some can reach several millimeters. Chondrules are found in a detrital or finely crystalline matrix, and often the matrix differs from chondrules not so much in composition as in crystalline structure. The composition of chondrites almost completely replicates the chemical composition of the Sun, with the exception of light gases such as hydrogen and helium. Therefore, it is believed that chondrites formed directly from the protoplanetary cloud that surrounded and surrounded the Sun, through the condensation of matter and the accretion of dust with intermediate heating.

Achondrites make up 7.3% of stony meteorites. These are fragments of protoplanetary (and planetary?) bodies that have undergone melting and differentiation by composition (into metals and silicates).

Iron meteorites are composed of an iron-nickel alloy. They account for 5.7% of falls.

Iron silicate meteorites have a composition intermediate between stony and iron meteorites. They are relatively rare (1.5% incidence).

Achondrites, iron and iron-silicate meteorites are classified as differentiated meteorites. They presumably consist of matter that has undergone differentiation in the composition of asteroids or other planetary bodies. Previously, it was believed that all differentiated meteorites were formed as a result of the rupture of one or more large bodies, for example the planet Phaethon. However, an analysis of the composition of various meteorites showed that they were more likely formed from the debris of many large asteroids.

Previously, tektites, pieces of siliceous glass of impact origin, were also isolated. But later it turned out that tektites are formed when a meteorite hits rock rich in silica.

3.2. Classification by detection method

• falls (when a meteorite is found after observing its fall in the atmosphere);
• finds (when the meteorite origin of the material is determined only by analysis);

4. Traces of extraterrestrial organics in meteorites

4.1. Coal complex

Carbonaceous (carbonaceous) meteorites have one important feature- the presence of a thin glassy cortex, apparently formed under the influence high temperatures. This crust is a good heat insulator, thanks to which minerals that cannot withstand strong heat, such as gypsum, are preserved inside carbonaceous meteorites. Thus, it became possible during the study chemical nature similar meteorites to find in their composition substances that in modern terrestrial conditions are organic compounds of biogenic nature:

• Saturated hydrocarbons
  • • Isoprenoids
    • n-Alkanes
    • Cycloalkanes

• Aromatic hydrocarbons
  • • Naphthalene
    • Alkybenzenes
    • Acenaphthenes
    • Pyrene

• Carboxylic acids
  • • Fatty acid
    • Benzenecarboxylic acids
    • Hydroxybenzoic acids

• Nitrogen compounds
  • • Pyrimidines
    • Purines
    • Guanylurea
    • Triazines
    • Porphyrins

The presence of such substances does not allow us to unambiguously declare the existence of life outside the Earth, since theoretically, if certain conditions were met, they could be synthesized abiogenically.

On the other hand, if the substances found in meteorites are not products of life, then they may be products of pre-life - similar to that which once existed on Earth.

4.2. "Organized Elements"

When studying stony meteorites, so-called “organized elements” are discovered - microscopic (5-50 microns) “single-cell” formations, often having clearly defined double walls, pores, spines, etc.

To date, it is not an indisputable fact that these fossils belong to the remains of any forms of extraterrestrial life. But, on the other hand, these formations have such high degree an organization that is usually associated with life.

In addition, such forms have not been found on Earth.

A feature of “organized elements” is also their large number: per 1g. The substances of the carbonaceous meteorite account for approximately 1800 “organized elements”.

5. Large modern meteorites discovered in Russia

• Tunguska phenomenon (at the moment, the exact meteorite origin of the Tunguska phenomenon is unclear. For details, see the article Tunguska meteorite). Fell on June 30, 1908 in the Podkamennaya Tunguska River basin in Siberia. Total energy is estimated at 15.40 megatons TNT equivalent.
• Tsarevsky meteorite (meteor shower). Fell on December 6, 1922 near the village of Tsarev Volgograd region. This is a rock meteorite. The total mass of the collected fragments is 1.6 tons over an area of ​​about 15 square meters. km. The weight of the largest fallen fragment was 284 kg.
• Sikhote-Alin meteorite ( total weight fragments 30 tons, energy is estimated at 20 kilotons). It was an iron meteorite. Fell in the Ussuri taiga on February 12, 1947.
• Vitimsky car. Fell near the villages of Mama and Vitimsky, Mamsko-Chuysky district Irkutsk region on the night of September 24-25, 2002. The event had a great public resonance, although the total energy of the meteorite explosion is apparently relatively small (200 tons of TNT equivalent, with an initial energy of 2.3 kilotons), the maximum initial mass (before combustion in the atmosphere) is 160 tons, and the final mass of the fragments is about several hundred kilograms.

The discovery of a meteorite is a rather rare occurrence. The Meteoritics Laboratory reports: “In total, only 125 meteorites have been found on the territory of the Russian Federation over 250 years.”

6. Interesting facts

The only documented case of a meteorite hitting a person occurred on November 30, 1954 in Alabama. The meteorite, weighing about 4 kg, crashed through the roof of the house and ricocheted Anna Elizabeth Hodges on the arm and thigh. The woman received bruises.

In 1875, a meteorite fell in the Lake Chad region ( Central Africa) and reached, according to the stories of the aborigines, 10 meters in diameter. After information about him reached the Royal Astronomical Society of Great Britain, an expedition was sent to him (15 years later). Upon arrival at the place, it turned out that elephants had destroyed it, having chosen it to sharpen their tusks. The crater was destroyed by rare but heavy rains.

7. Individual meteorites

• Omolon

• Alfianello
• Allende
• Anthony
• Arapahoe
• Arcadia
• Armel
• Ashmore

• Bansur
• Barratta
• Beaver
• Beeler
• Bencubbin
• Bjurbole
• Bledsoe
• Bondoc
• Boxhole
• Breitscheid
• Buenaventura

• Calliham
• Channing
• Chainpur
• Chico