Any celestial body larger than cosmic dust, but inferior to an asteroid, is called a meteoroid. A meteoroid that has fallen into the earth's atmosphere is called a meteor, and one that fell to the earth's surface is called a meteorite.
Travel speed in space
The speed of meteoroid bodies moving in outer space can be different, but in any case it exceeds the second cosmic speed, equal to 11.2 km / s. This speed allows the body to overcome the gravitational pull of the planet, but it is inherent only in those meteoric bodies that were born in the solar system. For meteoroids that come from outside, higher speeds are also characteristic.
The minimum speed of a meteoric body when it meets the planet Earth is determined by how the directions of motion of both bodies are related. The minimum is comparable to the speed of the Earth's orbital motion - about 30 km / s. This applies to those meteoroids that move in the same direction as the Earth, as if catching up with it. There are most of such meteoric bodies, because meteoroids arose from the same rotating protoplanetary cloud as the Earth, therefore, must move in the same direction.
If the meteoroid moves towards the Earth, then its speed is added to the orbital one and therefore turns out to be higher. The velocity of bodies from the Perseids meteor shower, through which the Earth passes every year in August, is 61 km / s, and the meteoroids from the Leonid stream, which the planet meets between November 14 and 21, has a speed of 71 km / s.
The highest speed is typical for comet fragments, it exceeds the third cosmic speed - such that allows the body to leave the solar system - 16.5 km / s, to which you need to add the orbital speed and make corrections for the direction of movement relative to the Earth.
Meteoroid in the earth's atmosphere
In the upper layers of the atmosphere, air almost does not interfere with the movement of the meteor - it is too rarefied here, the distance between gas molecules can exceed the size of an average meteoroid. But in denser layers of the atmosphere, the friction force begins to affect the meteor, and its movement slows down. At an altitude of 10-20 km from the earth's surface, the body falls into the delay region, losing its cosmic velocity and, as it were, hovering in the air.
Subsequently, the resistance of the atmospheric air is balanced by the earth's gravity, and the meteor falls to the surface of the earth like any other body. In this case, its speed reaches 50-150 km / s, depending on the mass.
Not every meteor reaches the earth's surface, becoming a meteorite; many burn up in the atmosphere. You can distinguish a meteorite from an ordinary stone by the melted surface.
Advice 2: What harm can an asteroid flying close to Earth do
The probability of the Earth meeting with a large asteroid is rather small. Nevertheless, it cannot be completely ruled out, the probability of an asteroid passing near our planet is slightly higher. Despite the fact that there is no direct collision in this case, the appearance of an asteroid near the Earth still carries a number of threats.
During its existence, the Earth has already collided with asteroids, and each time this led to dire consequences for its inhabitants. On the planet's surface, more than one and a half hundred craters have been identified, some of which are 100 km in diameter.
The fact that the fall of a large asteroid will lead to catastrophic destruction is well understood by any sane person. It is no coincidence that scientists from leading countries of the world have been tracking the flight trajectories of the most dangerous space bodies for decades, developing options for countering the asteroid threat.
One of the most dangerous for earthlings is the asteroid Apophis; according to forecasts, it will approach the Earth in 2029 at a distance of 28 to 37 thousand kilometers. This is 10 times less than the distance to the Moon. And although scientists claim that the probability of a collision is negligible, such a close passage of an asteroid can be serious for the planet.
Apophis is relatively small, with a diameter of only 270 meters. But every asteroid is surrounded by a whole cloud of small particles, many of which can harm the spacecraft launched into orbit. At speeds of up to several tens of kilometers per second, even a speck of dust can cause serious damage. Apophis will pass there, geostationary satellites, it is they who are most threatened by its small debris.
Some of the matter of asteroids flying near the Earth can fall on its surface, this also conceals its own. Scientists suggest that it is comets that can transfer microscopic organisms from one planet to another. The probability of this is small, but it cannot be completely ruled out.
Despite the fact that the debris of the celestial wanderer that has fallen into the atmosphere of the planet is heated to a high temperature, some organisms may well survive. And this, in turn, is a very big threat to all life on Earth. Microorganisms alien to the earth's flora and fauna can become deadly and, if they multiply rapidly, lead to the death of mankind.
Such scenarios look very unlikely, but in reality they are quite possible. Earth medicine still fails to cope even with the flu, which annually leads to the death of hundreds of thousands of people. Now imagine a microorganism that has a tenfold higher lethality, multiplies rapidly and can spread easily. Its appearance in a large city will be a real disaster, since it will be very difficult to keep the epidemic that has begun.
Space bodies are constantly falling on our planet. Some of them are the size of a grain of sand, others can weigh several hundred kilograms or even tons. Canadian scientists from the Ottawa Astrophysical Institute claim that a meteorite shower with a total mass of more than 21 tons falls to the Earth every year, and individual meteorites weigh from several grams to 1 ton.
In this article, we will recall the 10 largest meteorites that fell to Earth.
Sutter Mill meteorite, 22 April 2012
This meteorite, called the Sutter Mill, appeared on Earth on April 22, 2012, moving at a breakneck speed of 29 km / sec. It flew over the states of Nevada and California, scattering its incandescent ones, and exploded over Washington. The power of the explosion was about 4 kilotons of TNT. For comparison, the power of yesterday's meteorite explosion when falling to Chelyabinsk was 300 tons in TNT equivalent. Scientists have found that the Sutter Mill meteorite appeared in the early days of the existence of our solar system, and the cosmic progenitor body was formed over 4566.57 million years ago. Fragments of the Sutter Mill meteorite:Meteor shower in China, February 11, 2012
Almost a year ago, on February 11, 2012, about a hundred meteorite stones fell over an area of \u200b\u200b100 km in one of the regions of China. The largest meteorite found weighed 12.6 kg. It is believed that the meteorites came from the asteroid belt between Mars and Jupiter.
Meteorite from Peru, 15 September 2007
This meteorite fell in Peru near Lake Titicaca, near the border with Bolivia. Eyewitnesses claimed that at first there was a loud noise, similar to the sound of a falling plane, but then they saw a certain falling body engulfed in fire. A bright trace from a space body heated to white heat that entered the Earth's atmosphere is called a meteor.
A crater with a diameter of 30 and a depth of 6 meters was formed at the site of the fall from the explosion, from which a fountain of boiling water began to flow. The meteorite likely contained poisonous substances as 1,500 people living nearby developed severe headaches.
By the way, most often stone meteorites (92.8%), consisting mainly of silicates, fall to the Earth. The meteorite that fell on Chelyabinsk was iron, according to the first estimates. Fragments of the Peruvian meteorite:
Meteorite Kunya-Urgench from Turkmenistan, June 20, 1998
The meteorite fell near the Turkmen city of Kunya-Urgench, hence its name. Before the fall, the inhabitants saw a bright light. The largest part of the meteorite, weighing 820 kg, fell into a cotton field, forming a crater about 5 meters.
This age of more than 4 billion years received a certificate from the International Meteorite Society and is considered the largest stone meteorite of all that fell in the CIS and the third in the world. Fragment of the Turkmen meteorite:
Sterlitamak meteorite, May 17, 1990
An iron meteorite Sterlitamak weighing 315 kg fell on a state farm field 20 km west of the city of Sterlitamak on the night of May 17-18, 1990. When the meteorite fell, a crater with a diameter of 10 meters was formed. First, small metal fragments were found, and only a year later, at a depth of 12 meters, the largest fragment weighing 315 kg was found. Now the meteorite (0.5 x 0.4 x 0.25 meters) is in the Museum of Archeology and Ethnography of the Ufa Scientific Center of the Russian Academy of Sciences. Fragments of a meteorite. On the left is the same splinter weighing 315 kg:
Largest meteor shower, China, 8 March 1976
In March 1976, China's Jilin province experienced the largest meteorite stone rain in the world, lasting 37 minutes. Cosmic bodies fell to the ground at a speed of 12 km / sec. Fantasy on the theme of meteorites:
Then they found about a hundred meteorites, including the largest - the 1.7-tonne Jilin (Jirin) meteorite.
These are the pebbles that fell from the sky to China for 37 minutes:
Sikhote-Alin meteorite, Far East, February 12, 1947
A meteorite fell in the Far East in the Ussuri taiga in the Sikhote-Alin mountains on February 12, 1947. It shattered in the atmosphere and fell in the form of iron rain over an area of \u200b\u200b10 square kilometers.
After the fall, more than 30 craters with a diameter of 7 to 28 m and a depth of up to 6 meters were formed. Was collected about 27 tons of meteorite matter. Fragments of the "piece of iron" that fell from the sky during a meteor shower:
Goba Meteorite, Namibia, 1920
Meet Goba - the largest meteorite found! Strictly speaking, it fell fell about 80,000 years ago. This iron giant weighing about 66 tons and a volume of 9 cubic meters. fell in prehistoric times, and was found in Namibia in 1920 near Grotfontein.
The Goba meteorite is mostly iron and is considered the heaviest of all celestial bodies of this kind that have ever appeared on Earth. It is preserved at the site of a fall in southwestern Africa, in Namibia, near the Goba West farm. It is also the largest natural iron lump on Earth. Since 1920, the meteorite has slightly decreased: erosion, scientific research and vandalism have done their job: the meteorite "lost weight" to 60 tons.
Mystery of the Tunguska meteorite, 1908
On June 30, 1908, at about 07:00 in the morning, a large fireball flew over the territory of the Yenisei basin from southeast to northwest. The flight ended with an explosion at an altitude of 7-10 km above an unpopulated area of \u200b\u200bthe taiga. The blast wave circled the globe twice and was recorded by observatories around the world. The explosion power is estimated at 40-50 megatons, which corresponds to the energy of the most powerful hydrogen bomb. The flight speed of the space giant was tens of kilometers per second. Weight - from 100 thousand to 1 million tons!
Podkamennaya Tunguska river area:
As a result of the explosion, trees were felled on an area of \u200b\u200bover 2,000 square meters. km, window panes in houses were shattered several hundred kilometers from the epicenter of the explosion. The blast wave in a radius of about 40 km destroyed the animals, people suffered. For several days, an intense glow of the sky and glowing clouds were observed in the territory from the Atlantic to central Siberia.
A meteorite is a piece of matter of cosmic origin that has fallen to the surface of any large celestial object. Literally, a meteorite is translated as "a stone from the sky." The overwhelming majority of meteorites that have been found on earth have weights from a few grams to several kilograms. Goba - the largest meteorite found, weighed about 60 tons. Scientists believe that up to 5 tons of meteorites fall to the Earth every day. But until recently, their existence was not recognized by well-known academics and space research specialists. All information and hypotheses about their extraterrestrial origin were recognized as pseudoscientific and were suppressed in the bud.
Meteorites are considered the oldest known mineral, dating back up to 4.5 billion years. Therefore, scientists believe that they must retain the remnants of the processes that accompanied the formation of planets. Meteorites remained the only unique samples of extraterrestrial origin until samples of lunar soil were brought to Earth. Chemists, geologists and physicists have been collecting information and studying meteorites in depth for over two hundred years. This knowledge gave impetus to the development of a new science of meteorites. People have known about the fall of celestial bodies to the Earth since ancient times, and some peoples even revered and worshiped them. Only scientists were very skeptical about them. But facts and common sense prevailed, over time it became meaningless to deny their cosmic origin.
Classification of meteorites
There are several types and names of meteorites: siderolites, uranolites, aerolites, meteor stones and others. Any space body before entering the atmosphere is called a meteoric body. It is classified according to various astronomical characteristics. It can be a meteorite, asteroid, cosmic dust, debris, etc. Flying through the earth's atmosphere and leaving a bright glowing trail, the object can be called a fireball or meteor. A solid body that fell to the surface of the Earth and left a characteristic depression - a crater - is considered a meteorite. It is customary to give them "names" according to the names of the places where they were found.
Stone meteorites are divided into two subclasses: chondrites and achondrites. Chondrites are so named because almost all of them contain chondrules - spheroidal formations of predominantly silicate composition. Chondrules are the most primitive types of meteorites. They are located in a fine crystalline matrix, and most of the chondrules are less than 1 mm in diameter. Chondrites can be up to 4.5 billion years old.
Less than 10% of the total number of stony meteorites form the subclass of achondrites. Achondrites are very similar to terrestrial igneous rocks. They are devoid of chondrules and consist of matter that was formed as a result of the melting processes of planetary and protoplanetary and planetary bodies. Most of the meteorites falling to Earth come from the asteroid belt located between Mars and Jupiter, and this is not surprising. After all, the largest and most famous cluster of meteorite bodies is observed there.
By the nature of detection, meteorites are divided into "fallen" and "found". Found, consider those meteorites, the fall of which was not observed by man. Their belonging to celestial bodies is established by studying the characteristics of their composition. The overwhelming majority of meteorites in private collections and world museums are finds. Very often, stone meteorites go simply unnoticed, since they can easily be confused with ordinary terrestrial rocks.
Meteors are particles of interplanetary material that pass through the Earth's atmosphere and are heated to incandescence by friction. These objects are called meteoric bodies and they rush through space, becoming meteors. In seconds, they cross the sky, creating glowing paths.
Meteor showers
Scientists have calculated that 44 tons of meteorite matter falls to Earth every day. Several meteors per hour can usually be seen any night. Sometimes the number rises sharply - these phenomena are called meteor showers. Some occur annually or at regular intervals as the Earth passes through the trail of dusty debris left by the comet.
Leonids meteor shower
Meteor showers are usually named after the star or constellation closest to where meteors appear in the sky. Perhaps the most famous are the Perseids, which appear on August 12 every year. Each meteor - Perseid - is a tiny piece of Comet Swift-Tuttle, which orbits the Sun for 135 years.
Other meteor showers and associated comets are the Leonids (Tempel-Tuttle), Aquarids and Orionids (Halley), and Taurids (Encke). Most of the cometary dust in meteor showers burns up in the atmosphere before reaching the Earth's surface. Some of this dust is caught by aircraft and analyzed in NASA laboratories.
Meteorites
Pieces of rock and metal from asteroids and other space bodies that survive travel through the atmosphere and fall to earth are called meteorites. Most of the meteorites found on Earth are pebbly, fist-sized, but some are larger than buildings. At one 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, formed by the fall of a lump of iron-nickel metal about 50 meters (164 ft) in diameter. It is 50,000 years old and is 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 Meteorite Crater
A severe asteroid impact 65 million years ago, which created the 300 kilometers (180 mi) wide Chicxulub crater in the Yucatan Peninsula, contributed to the extinction of about 75 percent of the 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 being hit by a 3.6 kilogram (8 lb) rock meteorite on the roof of her home in November 1954.
Meteorites may look like earth rocks, but they usually have a burnt surface. This burnt crust results from frictional melting of a meteorite as it passes through the atmosphere. There are three main types of meteorites: silvery, stony, and stony-silvery. Although most of the meteorites that fall to Earth are stone, more of the meteorites discovered recently are silvery. These heavy objects are easier to distinguish from earth rocks than stone meteorites.
This meteorite image was captured by the Opportunity rover in September 2010.
Meteorites also fall on other bodies in the solar system. The Opportunity rover explored 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 nickel-iron meteorite in the same area in 2009. In all, the Opportunity rover discovered six meteorites during its journey across 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 origin from asteroids includes the calculated from photographic observations of the orbit of a meteorite falling projected back into the asteroid belt. Analysis of several classes of meteorites showed 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 find the correspondence of one group of meteorites to a certain type of asteroid - eucrite, diogenite and howardite. These magmatic meteorites originate from the third largest asteroid Vesta. The asteroids and meteorites that fall to Earth are not parts of the planet that disintegrated, but are composed of the original materials from which the planets were 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 solids, the nature of organic matter, the temperatures reached at the surface and within the asteroids, and the shape into which these materials were brought by the collision.
The remaining 0.2 percent of meteorites can be roughly divided into meteorites from Mars and the Moon. More than 60 known Martian meteorites have been ejected from Mars by a meteor shower. All of them are igneous rocks that have crystallized from magma. The stones are very similar to those on Earth, with some distinctive features that indicate their Martian origin. Nearly 80 lunar meteorites are similar in mineralogy and composition of moon rocks from the Apollo mission, but different enough to show that they came from different parts of the moon. Exploration of lunar meteorites and Martian meteorites complements the exploration of the lunar rocks of 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 this is easy to explain. Iron meteorites are dense, very heavy, and often take on unusual and even spectacular shapes as they fall and melt in our planet's atmosphere. Although iron is associated by most people with the typical composition of space rocks, iron meteorites are one of the three main types of meteorites. And they are quite rare in comparison with stone meteorites, especially with the most common group of them - single chondrites.
Three main types of meteorites
There are many types of meteorites, divided into three main groups: iron, stone, stone-iron. Nearly all meteorites contain extraterrestrial nickel and iron. Those of them that do not contain iron at all are so rare that even if we ask for help in identifying possible space stones, we most likely will not find anything that does not contain a large amount of metal. The classification of meteorites is, in fact, based on the amount of iron in the sample.
The iron meteorites were part of the core of a long-dead planet or a 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 attracted to a strong magnet. Iron meteorites are much heavier than most of the earth's rocks, if you've lifted a cannonball or a slab of iron or steel, you know what this is about.
An example of an iron meteorite
Most of the samples in this group have an iron content of about 90% -95%, the rest is nickel and trace elements. Iron meteorites are classified into classes according to their chemical composition and structure. Structural classes are determined by studying two components of iron-nickel alloys: kamacite and tenite.
These alloys have a complex crystalline structure known as the Widmanstätten structure, named after Count Alois von Widmanstetten who described the phenomenon in the 19th century. This lattice-like structure is very beautiful and is clearly visible if an iron meteorite is cut into plates, polished and then etched in a weak solution of nitric acid. In the kamacite crystals found in the process, the average width of the bands is measured, the resulting figure is used to classify iron meteorites into structural classes. Iron with a thin strip (less than 1 mm) is called "fine-structured octahedrite", with a wide strip "coarse octahedrite".
Stone meteorites
The largest group of meteorites is stone, they formed from the outer crust of a planet or an asteroid. Many stone meteorites, especially those that have been on the surface of our planet for a long time, are very similar to ordinary earth rocks, and it takes an experienced eye to find such a meteorite in the field. Recently fallen stones feature a black glowing surface that was formed by 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. The stony meteorites containing these chondrules are called chondrites.
Cosmic stones without chondrules are called achondrites. These are volcanic rocks, formed by volcanic activity on their "parent" space objects, where melting and recrystallization has erased all traces of ancient chondrules. Achondrites contain little or no iron, making it difficult to find when compared to other meteorites, although specimens are often covered with a glossy crust that looks like enamel paint.
Stone meteorites from the Moon and Mars
Can we really find lunar 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, and they all belong to the achondrite group.
Lunar meteorite
The collision of the surface of the Moon and Mars with other meteorites threw the fragments into open space and some of them fell to the Earth. From a financial standpoint, lunar and Martian specimens are among the most expensive meteorites. In collector's markets, their prices go up to thousands of dollars per gram, which makes them several times more expensive than if they were made of gold.
Stone-iron meteorites
The least common of the three main types is stone-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: pallasites and mesosiderites. Stone-iron meteorites formed on the border of the crust and mantle of their "parent" bodies.
An example of a stone-iron meteorite
Pallasites are perhaps the most tempting 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 appear emerald green, they are known as the Perodotus gem. The Pallasites got their name in honor of the German zoologist Peter Pallas, who described the Russian meteorite Krasnoyarsk, found near the capital of Siberia in the 18th century. When a pallasite crystal is cut into plates and polished, it becomes translucent, giving it an unearthly beauty.
Mesosiderites are the smaller of the two stone-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 you cut off the plate and grind, and random blotches, leads to a very unusual look. The word mesosiderite comes from the Greek "half" and "iron," and they are very rare. In the 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 brief overview of the topic. The classification methods have changed several times in recent years; known meteorites have been reclassified to a different class.
Martian meteorites
The Martian meteorite is a rare type of meteor that came from the planet Mars. Until November 2009, more than 24,000 meteors were found on Earth, but only 34 of them are Martian. The Martian origin of meteors was known from the composition of the isotopic gas, which is contained in meteors in microscopic quantities, the analysis of the Martian atmosphere was made by the Viking spacecraft.
The emergence of the Martian meteorite Nakhla
In 1911, the first Martian meteorite, Nakhla, was found in the Egyptian desert. The appearance 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 to Mars or during massive volcanic eruptions. The force of the explosion was such that the discarded pieces of rock acquired the speed necessary to surpass the gravity of the planet Mars and leave its orbit (5 km / s). In our time, up to 500 kg of Martian stones fall to the Earth in one year.
Two parts of the Nakhla meteorite
In August 1996, Science published an article on the study of the ALH 84001 meteorite, found in Antarctica in 1984. New work has begun, centered around a meteorite discovered in an Antarctic glacier. The study was carried out using a scanning electron microscope, they revealed "biogenic structures" inside the meteor, which theoretically could be formed by life on Mars.
The isotope date showed that the meteor appeared about 4.5 billion years ago, and hitting interplanetary space, fell to Earth 13 thousand years ago.
"Biogenic structures" found on a section of a meteorite
Examining the meteor with an electron microscope, the experts found microscopic fossils suggesting bacterial colonies made up of discrete pieces of approximately 100 nm in size. Traces of drugs arising from the decomposition of microorganisms were also found. Proof of the occurrence of a Martian meteor requires microscopic examination and special chemical analyzes. The presence of minerals, oxides, calcium phosphates, silicon and iron sulfide can testify to the Martian appearance of a meteor.
The known specimens are invaluable finds as they represent typical time capsules from the geological past of Mars. We received these Martian meteorites without any space missions.
The largest meteorites that fell to Earth
From time to time, space bodies fall to the Earth ... more and not very much, made of stone or metal. Some of them are no more than a grain of sand, others weigh several hundred kilograms or even tons. Scientists at the Astrophysical Institute of the city of Ottawa (Canada) claim that several hundred solid alien bodies with a total mass of more than 21 tons visit our planet a year. Most meteorites weigh less than a few grams, but there are those that weigh several hundred kilograms or even tons.
Places of falling meteorites are either fenced off or, on the contrary, opened up for everyone to see, 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 a bad omen. People tried to avoid 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 among the inhabitants of the planet.
Let's remember the 10 largest meteorites that fell on our planet.
A meteorite fell on our planet on April 22, 2012, the speed of the car was 29 km / s. Flying over the states of California and Nevada, the meteorite scattered its burning fragments for tens of kilometers and exploded in the sky over the capital of the United States. The explosion power is relatively small - 4 kilotons (in TNT equivalent). For comparison, the explosion of the famous Chelyabinsk meteorite was 300 kilotons in TNT.
According to scientists, the Sutter Mill meteorite was formed at the time of the birth of our solar system, to 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 PRC and fell over an area of \u200b\u200bover 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, loud noise preceded the event. Then they saw a body falling on fire. The meteorite left a bright trail in the sky and a plume of smoke, which was visible several hours after the fall of the fireball.
A huge crater 30 meters in diameter and 6 in depth formed at the site of the fall. The meteorite contained toxic substances, as people living nearby started having headaches.
Stone meteorites (92% of the total), consisting of silicates, most often fall on the Earth. The Chelyabinsk meteorite is an exception, it was made of iron.
The meteorite fell on June 20, 1998 near the Turkmen city of Kunya-Urgench, hence its name. Before the fall, the locals saw a bright flash. The largest part of the car weighs 820 kg, this piece fell into the field and formed a funnel of 5 meters.
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 on the territory of the CIS and third world countries.
The iron bolide Sterlitamak, whose weight was more than 300 kg, fell on May 17, 1990 on the field of the state farm west of the city of Sterlitamak. When a celestial body fell, a crater of 10 meters was formed.
Initially, small metal fragments were discovered, a year later, scientists managed to extract the largest fragment of a meteorite weighing 315 kg. At present, 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 (Jilin), weighed 1.7 tons.
This meteorite fell on February 12, 1947 in the Far East in the city of Sikhote-Alin. The car was shattered in the atmosphere into small iron pieces, which crumbled over an area of \u200b\u200b15 square kilometers.
Several dozen craters 1-6 meters deep and 7 to 30 meters in diameter 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. The 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.
Composition of the meteorite. 80% of this celestial body consists of iron, it 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 at the crash site. It is one of the largest pieces of iron on Earth of extraterrestrial origin. The meteorite is constantly decreasing: erosion, vandalism and scientific research have done their job: the meteor has decreased by 10%.
A special fence was created around it, and now Goba is known throughout the planet, many tourists come to it.
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 one hundred 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. The blast wave knocked out a window in nearby settlements.
As a result of the explosion, trees fell. Forest area of \u200b\u200b2,000 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 the glow of the sky. According to scientists, this was caused by inert gases that were released when the meteorite entered the Earth's atmosphere.
What was it? The meteorite would leave a huge crater at least 500 meters deep at the site of the fall. No expedition has been able to find anything like this ...
The Tunguska meteor, on the one hand, is a well-studied phenomenon, on the other, it is one of the biggest mysteries. The celestial body exploded in the air, the pieces burned up in the atmosphere, and no remnants remained on Earth.
The working title "Tunguska meteorite" appeared because it is the simplest and most understandable explanation of the flying burning ball that caused the explosion effect. The Tunguska meteorite was also called a crashed alien ship, a natural anomaly, and a gas explosion. What he was in reality - one can only guess and build hypotheses.
Meteor shower in the USA (1833)
On November 13, 1833, a meteor shower fell over the eastern territory of the United States. The duration of the meteor shower is 10 hours! During this time, about 240 thousand small and medium meteorites fell on the surface of our planet. The 1833 meteor shower is the most powerful meteor shower known.
Every day, dozens of meteor showers fly by near our planet. There are about 50 known potentially dangerous comets that can cross the Earth's orbit. The collision of our planet with small (not capable of causing great harm) cosmic bodies occurs once every 10-15 years. A special danger for our planet is the fall of an asteroid.
Chelyabinsk meteorite
Almost two years have passed since the residents of South Urals were eyewitnesses of a cosmic cataclysm - the fall of the Chelyabinsk meteorite, which became for the first time in modern history a case that caused significant damage to the local population.
The fall of the asteroid occurred in 2013, on February 15. At first it seemed to the South Urals as if an "obscure object" had exploded, many saw strange lightning flashes illuminating the sky. This is the opinion of the scientists who studied this incident during the year.
Meteorite data
In the area near Chelyabinsk, a fairly ordinary comet fell. Falls of space objects of exactly this nature occur once in a century. Although, according to other sources, they happen repeatedly, on average, up to 5 times in 100 years. According to scientists, comets of about 10 m in size fly into the atmosphere of our Earth approximately once a year, which is 2 times more than the Chelyabinsk metorite, but often this 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 the Chelyabinsk meteorite in the sky
Before the fall, the mass of the Chelyabinsk aerolite ranged from 7 to 13 thousand tons, and its parameters supposedly reached 19.8 m. After analyzing, scientists found that about 0.05% of the initial mass fell to the surface of the earth, this is 4-6 tons. At present, a little more than one ton has been collected from this amount, taking into account one of the large aerolite fragments weighing 654 kg, raised from the bottom of the Chebarkul Lake.
Geochemical studies of the Chelyabinsk maetorite revealed that it belongs to the type of ordinary chondrites of the LL5 class. 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.
The readings of infrasound stations indicate that at the moment of strong deceleration of the Chelyabinsk aerolite, when about 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 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, as a result of which it caused significant damage. So, during the explosion of a meteorite, the windows of more than 7 thousand houses were knocked out, more than one and a half thousand people sought medical help, of which 112 were hospitalized.
In addition to the significant damage, the meteorite falling also brought positive results. This event is the best documented to date. In addition, one video camera filmed the phase of one of the large fragments of the asteroid falling into Lake Chebarkul.
Where did the Chelyabinsk meteorite come from?
For scientists, this question was not difficult. It emerged from the main asteroid belt of our solar system, the 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, asteroids of the Aton or Apollo group, are oblong and can pass through the Earth's orbit.
Astronomers were able to accurately determine the flight trajectory of the "Chelyabinsk", thanks to many photographs and videos, as well as satellite photographs that captured the fall. Then astronomers continued the path of the meteorite in the opposite direction, behind the atmosphere, in order to build a complete orbit of this object.
Sizes 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, one can see that the semi-major axis of the orbit of the fallen meteorite was equal to 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 farthest from the Sun was aphelion, or apogelium, at 2.6 AU.
These figures allowed scientists to try to find the Chelyabinsk meteorite in the astronomical catalogs of already identified small space objects. It is clear that most of the previously established asteroids, after some time, again "fall out of sight", and then some of the "losses" manage to "open" a second time. Astronomers did not reject this option, that the fallen meteorite, perhaps, is a "loss".
Relatives of the Chelyabinsk meteorite
Although the search did not reveal a complete similarity, astronomers nevertheless 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 of 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 (the Astronomical Institute of the Czech Academy of Sciences), headed by Jiri Borovichka, calculating 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 semi-major 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
Scientists "determined" its life history by the fragments of the Chelyabinsk meteorite that fell to the surface of the earth. It turns out that the Chelyabinsk meteorite is the same age as our solar system. When studying the proportions of the isotopes of uranium and lead, it turned out that it is approximately 4.45 billion years old.
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 blow were melted. This shows that approximately 290 million years ago, this asteroid withstood a powerful collision with some kind of cosmic object.
According to scientists from the Institute of Geochemistry and Analytical Chemistry. Vernadsky RAS, the collision took about several minutes. This is indicated by the streaks of iron nuclei, which 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 approach of a space body with the Sun.
Meteor showers
Several times a year, meteor showers like stars illuminate the clear night sky. But they really have nothing to do with the stars. These small cosmic meteorite particles are literally celestial debris.
Meteoroid, meteor or meteorite?
Whenever a meteoroid enters the Earth's atmosphere, it generates a flash of light called a meteor or "shooting star." The high temperatures caused by friction between a meteor and gas in the Earth's atmosphere heat the meteorite to the point where it starts glowing. This is the same glow that makes the meteor visible from the surface of the Earth.
Meteors usually glow for a very short period of time - they tend to be completely burned up 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 originate from the Asteroid Belt, although some pieces of debris have been identified as belonging to the Moon and Mars.
What are meteor showers?
Occasionally, meteors fall in a huge shower known as meteor showers. Meteor showers occur when a comet approaches the Sun and leaves trash behind in the form of a kind of "bread crumbs". When the orbit of the Earth and the comet intersect, a meteor shower hits the Earth.
So meteors that form a meteor shower move along 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 they come from.
Events
Scientists believe they have discovered the first meteorite to come to Earth from Mercury... An unusual green piece of stone was named NWA 7325. It was discovered in the south of Morocco in 2012 and was broken into 35 pieces with a total weight 345 grams.
Dark green stones were sold to a meteorite dealer Stefan Ralewwho sent samples to University of Washington specialists in meteorites of planetary origin.
The researchers found that these samples contain surprisingly low percentage of iron, but a large amount of silicates of magnesium, aluminum and calcium. These proportions correspond to the proportions of the surface of Mercury, judging by the data obtained by NASA's Messenger spacecraft.
However, the stone contains more calcium silicatethan is on the surface of Mercury, so scientists have made the assumption that perhaps this meteorite was once part of deeper layers of the planet... It most likely broke off in a powerful collision, was thrown into space, and eventually hit the surface of the Earth.
"This sample can be from Mercury, or from a smaller object, - said the scientists. - It is very likely that this rock formed as "foam" in the upper magma. "
Where do meteorites come from?
Guests from space meteorites - space stones, which often fall to the surface of our planet, have always interested scientists, since these unusual stones carry a lot of useful information about the origin of the planets and the entire solar system.
It is believed that a huge number of small meteorites fall on the Earth's surface per day - up to 5-6 tonshowever, they are mostly so small that their fall goes largely unnoticed. Moreover, most meteorites fall into the oceanwhere it is not possible to notice their fall or find them later.
Origin of meteorites
Mostly meteorites come to us from Asteroid belts - the region between the orbits of Mars and Jupiter - and are fragments of these smallest celestial bodies - asteroids... Asteroids, moving in their orbits, collide with each other, change direction, and some of them hit the Earth.
Younger meteorites are of Martian or lunar origin, some of them "only" about 180 million yearsthat, by cosmic standards, a rather small age. The composition of these meteorites is very similar to the composition of the soil of the Moon or Mars, which is why it is concluded where the meteorite came from.
Asteroid meteorites
Fragments of the planet Mars, which fell to Earth in the form of meteorites, have been found more than once, but evidence that these meteorites came from Mars was obtained only in the 1980swhen gas inclusions in their composition were discovered, corresponding to the gases of the atmosphere of Mars.
When celestial bodies, such as debris of asteroids or comets, collided with the surface of Mars, they split off from it pieces of native breedthat flew into outer space and, ultimately, could get to the neighboring planet - Earth.
Meteorites of Martian origin
The first lunar meteorites were discovered by the Americans in the early 1980s in Antarctica. Subsequently, moon stones began to be found in other parts of the planet - in the deserts of Australia and Africa. These stones were unusually similar in composition to samples of soil brought from the moon.
Lunar meteorites