What types of meteorites are there? Meteors and meteorites

> Types of meteorites

Find out which ones exist types of meteorites: description of classification with photos, iron, stone and stone-iron, meteorites from the Moon and Mars, asteroid belt.

Quite often, an ordinary person, imagining what a meteorite looks like, 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

There is a large number types of meteorites, divided into three main groups: iron, stone, stone-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.

Iron type meteorite

Iron meteoriteswere part of the core of a long-dead planet or large asteroid from which it is believed to have formed between Mars and Jupiter. They are the densest materials on Earth and are very strongly attracted to a strong magnet. Iron meteorites are much heavier than most Earth rocks; if you've lifted a cannonball or a slab of iron or steel, you know what we're talking about.

For most samples in 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 is clearly visible if the iron meteorite is cut into plates, polished and then etched 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 view of meteorite

The largest group of meteorites is stone, they formed from the outer crust of a planet or asteroid. Many rocky meteorites, especially those that have been on the surface of our planet for a long time, look very much like ordinary terrestrial rocks, and it takes an experienced eye to find such a meteorite in the field. Newly fallen rocks have a black, shiny surface that results from the surface burning in flight, and the vast majority of rocks contain enough iron to be attracted to a powerful magnet.

Some stony meteorites contain small, colorful, grain-like inclusions known as "chondrules." These tiny grains originated from the solar nebula, therefore predating the formation of our planet and the entire Solar System, making 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 by 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 view of meteorite 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.

The collision of the surface of the Moon and Mars with other meteorites threw fragments into outer 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.

Stone-iron type of meteorite

The least common of the three main types - stone-iron, accounts 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.

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 clear enough to display an emerald green color, they are known as a perodot gemstone. 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, when the plate is cut and sanded, and the occasional inclusions, results in a very unusual appearance. 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 meteorite types

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

From the history

Meteorites. These space wanderers have long excited the hearts of people. Looking into the night sky above our heads, each of us has at least once seen as if one of the stars is breaking out of its place and rapidly falling, drawing a bright trail in the sky. Imagine how surprised people were centuries and millennia ago when a meteorite fell before their eyes. A thunderous roar, hissing and crackling, a fireball streaks across the sky and falls with an incredible roar! The memory of this event became legends and myths, and people kept fragments of the heavenly stone as sacred relics. It is not surprising that even scientists for a long time refused to recognize meteorites as a reality, considering the stories about them fiction. And only studies in 1794 of the Pallas iron, a large meteorite found in Siberia, were able to confirm the extraterrestrial origin of these objects.

More than two hundred years have passed since then, and today meteorites are under the close attention of scientists from various branches of science. Meteorites have become part of the world's popular culture, appearing in films and science fiction novels. It’s time for us to finally find out what these guests from outer space are like.

What is a meteorite?

In addition to planets and stars, there are many different objects in space. There are asteroids - bodies similar to planets, but not nearly as huge. Asteroids have their own orbits around the Sun, some even have satellites. There is cosmic dust - tiny particles of matter dispersed in outer space. And there are intermediate objects, of medium size. Their sizes range from 0.1 mm to 10-30 m. They are called meteoroids. They can be dispersed in space, move along arbitrary trajectories, or have relatively stable orbits. Sometimes there is a whole cluster of meteoroids - the so-called swarm.

When such a meteoroid enters the gravitational field of the planet, its trajectory changes, and it gradually rushes towards the surface of the planet. Collisions between the planet and asteroids occasionally occur.

A colorful phenomenon in the form of a cosmic body burning in the atmosphere is called a meteor (or fireball).

And only when a cosmic body (no matter what size) reaches the surface of the planet can it be called the usual word - a meteorite.

What types of meteorites are there?

Of course, each meteorite is unique and no two meteorites are alike. But according to their composition, they are divided into three large groups.

Stone meteorites. This is the largest group. 92.8% of all meteorites that reach the earth are stone, and of these, 92.3% are called chondrites. Surprisingly, their composition is identical to the chemical composition of the Sun, with the exception of light gases, hydrogen and helium. How is this possible? The solar system formed from a giant interstellar cloud of gas and dust. Under the influence of gravity, matter rushed to the center, forming a protostar. Under the influence of the mass of matter falling on it, the temperature of the protostar increased and, as a result, thermonuclear reactions broke out in its center. This is how the Sun came into being. And the remains of matter from the gas and dust cloud formed all other space objects in the Solar System. Chondrites are precisely the smallest particles formed from the substance of a gas and dust cloud. We can say that both they and the Sun are made of the same material. The main minerals in their composition are various silicates.

All other meteorites have a complex origin, and are fragments of asteroids or planetary objects. Some of them are stone, like chondrites, but have a different composition and structure.

Metal meteorites are another large group, accounting for 5.7% of the total number of impacts on the earth. They are mainly composed of an alloy of iron and nickel, are very durable and are almost resistant to corrosion.

And finally, the rarest (and most beautiful) meteorites are the iron-stone ones. There are only 1.5% of them, but they have a complex structure in which the metal part is intertwined with silicate formations.

How many meteorites fall to Earth?

About 5-6 tons of meteorite matter fall to Earth per day. This amounts to about 2 thousand tons per year. It would seem like a solid figure. But most meteorites burn up in the atmosphere before reaching the ground. Of the rest, a significant portion falls into the ocean or sparsely populated areas - simply because they occupy most of our planet. And only in rare cases does a meteorite fall in a populated area, in front of people.

What happens when a meteorite falls?

Cosmic bodies move at enormous speeds. When entering the atmosphere, the speed of the meteorite can reach from 11 to 72 km/s. From friction with the air, it lights up and begins to glow. As a rule, most meteorites burn up before reaching the surface. A large meteorite gradually slows down and cools down. What happens next depends on many factors - mass, initial speed, angle of entry into the atmosphere. If the meteorite manages to slow down, its trajectory may change to almost vertical and it will simply fall to the surface. It happens that the internal structure of a meteorite is heterogeneous and unstable. And then it explodes in the air, and its fragments fall to the ground. This phenomenon is called meteor shower. But if the speed of the meteorite is still high (about 2-4 km/s), and it itself is quite massive, a powerful explosion occurs when it collides with the earth’s surface.

At the site of the fall of a large meteorite, a meteorite crater is formed - an astrobleme. On Earth, such craters are not always visible, because weathering and other geological processes destroy them. But on other planets you can see traces of colossal meteorite bombardments.

There are also meteorite craters in Russia. The largest of them is located in Eastern Siberia. This is the Popigai crater, its diameter is 100 km, and it is the fourth largest in the world. Parrot was formed 35.7 million years ago as a result of the collision of a large asteroid with the Earth. There is information that diamond deposits are hidden in its depths, but exact information about this was classified back in Soviet times. The oldest Russian crater (and one of the oldest in the world) is the small Suavjärvi crater in Karelia. Its diameter is only 3 km and now there is a lake in it. But its age - 2.4 billion years - is impressive.

Danger of meteorites.

The chance that a meteorite will hit a person is extremely low. In total, two reliable cases of a meteorite falling on a person were recorded, and both times people received minor bruises. Also, over the past two centuries, there is about a dozen evidence of the death of people from a meteorite strike, but they do not have official confirmation.

However, it would be unwise to deny the danger of meteorites. The example of the Chelyabinsk meteorite shows that even an indirect impact from the explosion of a large space object can be destructive.

In popular culture, there is a stereotype that meteorites can be radioactive or carry spores of monstrous alien diseases. These modern myths are supported by science fiction and cinema, but are without foundation. There have been no cases of detection of radioactive meteorites. No one.

In order for a piece of rock or meteorite to be radioactive, it must contain radioactive substances. For example, uranium. But over time, their radioactivity decreases. The rate of decrease in radioactivity is characterized by a value called the half-life. And this value is much less than the average age of any of the meteorites falling to Earth.

But there are sources of radiation in space, for example the sun? Yes, but you should understand that being irradiated does not mean becoming radioactive yourself. If you spend a weekend in a nuclear reactor, you're unlikely to feel good afterwards. But nevertheless, you will not emit radiation.

Some meteorites contain complex organic compounds, and because of this they are of great interest to scientists. But no microorganisms or traces of alien life have been found on them yet.

What are meteorites used for?

In ancient times, meteorites could serve as objects of religious worship. Meteoric iron was known long before people learned how to independently smelt iron from ore. Products made from meteorite iron were extremely highly valued; one example is the dagger found in the tomb of Tutankhamun.

Today meteorites are of more scientific interest. They can tell us a lot about the early life of our solar system and about distant worlds.

However, iron and stony-iron meteorites are used in jewelry. The structure of the crystal lattice itself gives them unique beauty. Intertwining needles of crystals, complex geometric shapes, fractal compositions. Scientifically, this phenomenon is called Widmanstätten figures. They are formed during the very slow cooling of an iron-nickel alloy heated to incredible temperatures. There is no air in space, there is no heat carrier, so the meteorite cools down over an infinitely long time - by several degrees in one million years. In stony-iron meteorites, the amorphous metal matrix hosts inclusions of silicates, including olivine. The yellow-green transparent varieties of this mineral are true gemstones. Such a structure and structural features cannot be created in artificial conditions. The appearance itself guarantees the authenticity and uniqueness of the jewelry created from a “fallen star” - a meteorite.

Most iron meteorites are quite resistant to terrestrial weathering, allowing them to survive much longer than any other type of meteorite. This means that the price for such meteorites will be slightly higher than for ordinary chondrites.

Iron meteorites tend to be much larger in size than stony or stony-iron meteorites. Iron meteorites rarely change shape when entering the atmosphere and suffer much less from the effects of ablation when passing through dense layers of air. All iron meteorites ever found on Earth weigh more than 500 tons, and they make up approximately 89.3% of the mass of all known meteorites. Despite these facts, iron meteorites are rare. Among the meteorites found, they are found only in 5.7% of cases.

Iron meteorites are composed primarily of iron and nickel. Most of them contain only minor mineral impurities. These accessory minerals often occur in rounded nodules that are composed of iron sulfide, troilite, or graphite, often surrounded by iron phosphide schreibersite and iron carbide cohenite. A classic example is the Campo del Cielo meteorite, the Willamette meteorite, or the Cape York meteorite. Although some iron meteorites contain silicate inclusions, most are similar in appearance.

Currently, iron meteorites are classified according to two established systems. Just a few decades ago, iron meteorites were classified according to their macroscopic structure when their polished surfaces were treated with nitric acid. Currently, a 5% solution of nitric acid in alcohol is used for these purposes.

In addition, modern research uses very sophisticated instruments that allow us to detect even minute quantities of elements such as germanium, gallium or iridium. Based on the specific concentrations of these elements and their correlation with total nickel content, iron meteorites are divided into several chemical groups, and each group is believed to represent a unique "imprint" of the parent body from which the meteorite originated.

Iron and nickel occur in iron meteorites as two different minerals. The most common mineral is kamacite. Kamacite contains between 4% and 7.5% nickel, and it forms large crystals that appear as broad bands or ray-like structures on the etched surface of the iron meteorite. Another mineral is called taenite.

Taenite contains between 27% and 65% nickel, and it typically forms smaller crystals that appear as reflective thin ribbons on the etched surface of the iron meteorite. Depending on the occurrence and presence of these nickel-iron minerals, iron meteorites are classified into three main classes: octahedrites, hexahedrites and ataxites.

Octahedrites

The most common display structure on the etched surface of iron meteorites is the accretion of kamacite and taenite in lamellae that intersect each other at different angles. These patterns of intersecting stripes and ribbons are called "Widmanstätten figures" in honor of their discoverer, Alois von Widmanstätten.

They show the intergrowth of kamacite and taenite into plates. This accretion has a spatial arrangement in the form of an octahedron, and therefore these iron meteorites are called octahedrites. The space between the kamacite and taenite plates is often filled with a fine-grained mixture called plessite.

Hexahedrites

Hexahedrites consist mainly of kamacite. They got their name from the shape of the crystalline structure of kamacite - a hexagon. The pure form of kamacite is a cubic crystal with six equal sides at right angles to each other.

After etching with nitric acid, hexahedrites do not exhibit Widmanstätten figures, but they often exhibit parallel lines called "Neumann Lines" (discovered by Franz Ernst Neumann, who first studied them in 1848).

Ataxites

Some iron meteorites do not show a clear internal structure when etched, and they are called ataxites. Ataxites consist primarily of nickel-rich taenite and kamacite. It is found only in the form of microscopic lamellas and spindles. Consequently, ataxites are the most nickel-rich iron meteorites and are among the rarest types of meteorites. Paradoxically, the largest meteorite found on Earth, known as Goba, belongs to this rare structural class.

Meteorites are small iron, stone or iron-stone space objects that regularly fall to the surface of the planets of the solar system, including the Earth. Outwardly, they are not much different from stones or pieces of iron, but they conceal many mysteries from the history of the universe. Meteorites help scientists uncover the secrets of the evolution of celestial bodies and study processes occurring far beyond our planet.

By analyzing their chemical and mineral composition, it is possible to trace patterns and connections between meteorites of different types. But each of them is unique, with qualities inherent only to this body of cosmic origin.

Types of meteorites by composition:

1. Stone:

Chondrites;

Achondrites.

2. Iron-stone:

Pallasites;

Mesosiderites.

3. Iron.

Octahedrites

Ataxites

4. Planetary

Martian

Origin of meteorites

Their structure is extremely complex and depends on many factors. Studying all known varieties of meteorites, scientists came to the conclusion that they are all closely related at the genetic level. Even taking into account significant differences in structure, mineral and chemical composition, they are united by one thing - origin. All of them are fragments of celestial bodies (asteroids and planets), moving in outer space at high speed.

Morphology

To reach the surface of the Earth, a meteorite needs to travel a long way through the layers of the atmosphere. As a result of significant aerodynamic load and ablation (high-temperature atmospheric erosion), they acquire characteristic external features:

Oriented conical shape;

Melting crust;

Special surface relief.

A distinctive feature of real meteorites is the melting crust. It can differ quite significantly in color and structure (depending on the type of body of cosmic origin). In chondrites it is black and matte, in achondrites it is shiny. In rare cases, the fusion bark may be light and translucent.

With a long stay on the surface of the Earth, the surface of the meteorite is destroyed under the influence of atmospheric influences and oxidation processes. For this reason, a significant part of bodies of cosmic origin after a certain time is practically no different from pieces of iron or stones.

Another distinctive external feature that a real meteorite has is the presence of depressions on the surface called piezoglypts or regmaglypts. Resembles fingerprints on soft clay. Their size and structure depend on the conditions of movement of the meteorite in the atmosphere.

Specific gravity

1. Iron - 7.72. The value can vary in the range of 7.29-7.88.

2. Pallasites – 4.74.

3. Mesosiderites – 5.06.

4. Stone - 3.54. The value can vary in the range of 3.1-3.84.

Magnetic and optical properties

Due to the presence of a significant amount of nickel iron, this meteorite exhibits its unique magnetic properties. This is used to verify the authenticity of a body of cosmic origin and allows indirect judgment of the mineral composition.

The optical properties of meteorites (color and reflectivity) are less pronounced. They appear only on the surfaces of fresh fractures, but over time due to oxidation they become less noticeable. Comparing the average values of the brightness coefficient of meteorites with the albedo of celestial bodies of the solar system, scientists came to the conclusion that some planets (Jupiter, Mars), their satellites, as well as asteroids are similar in their optical properties to meteorites.

Chemical composition of meteorites

Considering the asteroidal origin of meteorites, their chemical composition can differ quite significantly between objects of different types. This has a significant impact on the magnetic and optical properties, as well as the specific gravity of bodies of cosmic origin. The most common chemical elements in meteorites are:

1. Iron (Fe). It is the main chemical element. Occurs in the form of nickel iron. Even stony meteorites have an average Fe content of 15.5%.

2. Nickel (Ni). It is part of nickel iron, as well as minerals (carbides, phosphides, sulfides and chlorides). Compared to Fe, it is 10 times less common.

3. Cobalt (Co). Not found in pure form. Compared to nickel, it is 10 times less common.

4. Sulfur (S). Part of the mineral troilite.

5. Silicon (Si). It is part of the silicates that form the bulk of stone meteorites.

3. Orthorhombic pyroxene. Often found in stony meteorites, it is the second most common among silicates.

4. Monoclinic pyroxene. It is found rarely and in small quantities in meteorites, with the exception of achondrites.

5. Plagioclase. A common rock-forming mineral belonging to the feldspar group. Its content in meteorites varies widely.

6. Glass. It is the main component of stone meteorites. Contained in chondrules and also found as inclusions in minerals.

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 known case, an extraterrestrial object injured a person in the United States. 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 stony, more meteorites discovered recently are silvery. 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 in the solar system. The Opportunity rover was exploring different types of meteorites on another planet when it 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 of 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 the age and composition of the solids, the nature of the organic matter, the temperatures reached on the surface and inside the asteroids, and the form into which these materials were reduced by 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 rocks are very similar to those on Earth, with some distinctive features that indicate Martian origin. Nearly 80 lunar meteorites are similar in mineralogy and composition to 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
Quite often, an ordinary person, imagining what a meteorite looks like, 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
There are 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.

Iron meteorites
The iron meteorites were part of the core of a long-dead planet or large asteroid that is believed to have formed the Asteroid Belt between Mars and Jupiter. They are the densest materials on Earth and are very strongly attracted to a strong magnet. Iron meteorites are much heavier than most Earth rocks; if you've lifted a cannonball or a slab of iron or steel, you know what we're talking about.

Example of an iron meteorite

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

A typical representative of chondrites

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

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

Classification of meteorites
The classification of meteorites is a complex and technical subject and the above is intended only as a brief overview of the topic. Classification methods have changed several times over the 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. The Martian origin of the meteors was known from the composition of the isotopic gas contained in the 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. A new work has begun, centered around a meteorite discovered in an Antarctic glacier. The study was carried out using a scanning electron microscope and identified "biogenic structures" inside the meteor that could theoretically have been formed by life on Mars.

The isotope 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 made up of individual parts measuring approximately 100 nanometers in volume. 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 quintessential time capsules from Mars' geological past. We obtained these Martian meteorites without any space missions.

The largest 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, in our time, such cases are 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 the southern regions of 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 (92% of the total) consisting of silicates most often fall to Earth. 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 largest part 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 in the Far East in the city of Sikhote-Alin. The bolide was crushed 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 of extraterrestrial origin. The meteorite is constantly decreasing: erosion, vandalism and scientific research have taken their toll: the meteorite has decreased 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 fireball flew over the territory of the Yenisei. 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. The flight of the space giant is 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 settlements, a window was broken by the blast wave.

Trees fell as a result of the explosion. Forest territory 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 by noble gases that 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 this is the simplest and most understandable explanation of the flying burning ball that caused the explosion effect. The Tunguska meteorite has been called a crashed alien ship, 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)

On November 13, 1833, a meteor shower occurred over the eastern United States. 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 South Urals witnessed a cosmic cataclysm - the fall of the Chelyabinsk meteorite, which became the first time in modern history that caused significant damage 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 of space objects of precisely this nature occur once every 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.

Plume from the 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, a little more than one ton has been collected from this amount, 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 in the minute of strong braking of the Chelyabinsk aerolite, when approximately 90 km remained to the ground, a powerful explosion occurred with a force equal to the TNT equivalent of 470-570 kilotons, which is 20-30 times stronger than the atomic explosion in Hiroshima, but 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 sought medical help, of which 112 were hospitalized.

In addition to significant damage, the meteorite also brought positive results. This event is the best documented event to date. In addition, one video camera recorded 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 path of the meteorite in the opposite direction, beyond 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 is the average radius of the 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

His difficult biography is indicated by 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 a powerful collision with some kind of space object.

According to scientists from the Institute of Geochemistry and Analytical Chemistry named after. 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 begins to glow. 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 travel 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.