A meteor is a particle of dust or fragments of cosmic bodies (comets or asteroids), which, when entering the upper layers of the Earth's atmosphere from space, burn up, leaving behind a strip of light that we observe. A popular name for a meteor is a shooting star.
The Earth is constantly being bombarded by objects from space. They vary in size, from stones weighing several kilograms, to microscopic particles weighing less than a millionth of a gram. According to some experts, the Earth captures more than 200 million kg of various meteoric substances during the year. And about one million meteors flash every day. Only a tenth of their mass reaches the surface in the form of meteorites and micrometeorites. The rest burns up in the atmosphere, giving rise to meteor trails.
Meteoric matter usually enters the atmosphere at a speed of about 15 km/sec. Although, depending on the direction relative to the Earth's movement, the speed can range from 11 to 73 km/s. Medium-sized particles, heated by friction, evaporate, giving a flash of visible light at an altitude of about 120 km. Leaving a short-term trace of ionized gas and extinguishes to an altitude of about 70 km. The greater the mass of the meteor body, the brighter it flares. These traces, which last 10–15 minutes, can reflect radar signals. Therefore, radar techniques are used to detect meteors that are too faint to be observed visually (as well as meteors that appear in daylight).
No one observed this meteorite as it fell. Its cosmic nature has been established based on the study of matter. Such meteorites are called finds, and they make up about half of the world's meteorite collection. The other half are falls, “fresh” meteorites picked up shortly after they hit Earth. These include the Peekskill meteorite, with which our story about space aliens began. Falls are of greater interest to specialists than finds: some astronomical information can be collected about them, and their substance is not altered by terrestrial factors.
It is customary to name meteorites based on the geographical names of places adjacent to the place where they fell or were found. Most often this is the name of the nearest populated area (for example, Peekskill), but prominent meteorites are given more general names. The two biggest falls of the 20th century. occurred on the territory of Russia: Tunguska and Sikhote-Alin.
Meteorites are divided into three large classes: iron, stony and stony-iron. Iron meteorites are composed primarily of nickel iron. A natural alloy of iron and nickel does not occur in terrestrial rocks, so the presence of nickel in pieces of iron indicates its cosmic (or industrial!) origin.
Nickel iron inclusions are found in most stony meteorites, which is why space rocks tend to be heavier than terrestrial rocks. Their main minerals are silicates (olivines and pyroxenes). A characteristic feature of the main type of stony meteorites - chondrites - is the presence of round formations inside them - chondrules. Chondrites consist of the same substance as the rest of the meteorite, but stand out on its section in the form of individual grains. Their origin is not yet entirely clear.
The third class - stony-iron meteorites - are pieces of nickel iron interspersed with grains of stony materials.
In general, meteorites consist of the same elements as terrestrial rocks, but combinations of these elements, i.e. minerals may also be those that are not found on Earth. This is due to the peculiarities of the formation of bodies that gave birth to meteorites.
Among the falls, rocky meteorites predominate. This means that there are more such pieces flying in space. As for the finds, iron meteorites predominate here: they are stronger, better preserved in terrestrial conditions, and stand out more sharply against the background of terrestrial rocks.
Meteorites are fragments of small planets - asteroids that mainly inhabit the zone between the orbits of Mars and Jupiter. There are many asteroids, they collide, fragment, change each other’s orbits, so that some fragments, in their movement, sometimes cross the Earth’s orbit. These fragments give rise to meteorites.
It is very difficult to organize instrumental observations of meteorite falls, with the help of which their orbits can be calculated with satisfactory accuracy: the phenomenon itself is very rare and unpredictable. In several cases this was done, and all orbits turned out to be typically asteroidal.
Astronomers' interest in meteorites was primarily due to the fact that for a long time they remained the only examples of extraterrestrial matter. But even today, when the substance of other planets and their satellites becomes available for laboratory research, meteorites have not lost their importance. The substance that makes up the large bodies of the Solar System underwent a long transformation: it melted, was divided into fractions, and solidified again, forming minerals that no longer had anything in common with the substance from which everything was formed. Meteorites are fragments of small bodies that have not gone through such a complex history. Some types of meteorites - carbonaceous chondrites - generally represent weakly altered primary matter of the Solar system. By studying it, experts will learn from what large bodies of the solar system were formed, including our planet Earth.
Meteor shower
The main part of meteoric matter in the Solar System revolves around the Sun in certain orbits. The orbital characteristics of meteor swarms can be calculated from observations of meteor trails. Using this method, it was shown that many meteor swarms have the same orbits as known comets. These particles can be distributed throughout the orbit or concentrated in separate clusters. In particular, a young meteor swarm can remain concentrated near the parent comet for a long time. When, while moving in orbit, the Earth crosses such a swarm, we observe a meteor shower in the sky. The perspective effect gives rise to the optical illusion that meteors, which are actually moving on parallel trajectories, appear to be emanating from a single point in the sky, which is commonly called the radiant. This illusion is the perspective effect. In reality, these meteors are generated by particles of matter entering the upper atmosphere along parallel trajectories. These are a great number of meteors observed over a limited period of time (usually a few hours or days). Many annual flows are known. Although only some of them generate meteor showers. The Earth very rarely encounters a particularly dense swarm of particles. And then an exceptionally strong shower could occur, with tens or hundreds of meteors every minute. Typically a good regular shower produces about 50 meteors per hour.
In addition to many regular meteor showers, sporadic meteors are also observed throughout the year. They can come from any direction.
Micrometeorite
This is a particle of meteorite material that is so small that it loses its energy even before it could ignite in the Earth's atmosphere. Micrometeorites fall to Earth as a shower of tiny dust particles. The amount of substance that falls on Earth annually in this form is estimated at 4 million kg. The particle size is usually less than 120 microns. Such particles can be collected during space experiments, and iron particles, due to their magnetic properties, can be detected on the surface of the Earth.
Origin of meteorites
The rarity and unpredictability of the appearance of meteorite material on Earth causes problems in its collection. Until now, meteorite collections have been enriched primarily by samples collected by random eyewitnesses of falls or simply curious people who paid attention to strange pieces of matter. As a rule, meteorites are melted on the outside, and their surface often bears a kind of frozen “ripple” - regmaglypts. Only in places where heavy meteorite showers fall does a targeted search for samples bring results. True, recently places of natural concentration of meteorites have been discovered, the most significant of them in Antarctica.
If there is information about a very bright fireball that could result in a meteorite fall, you should try to collect observations of this fireball by random eyewitnesses over the largest possible area. It is necessary for eyewitnesses from the observation site to show the path of the car in the sky. It is advisable to measure the horizontal coordinates (azimuth and altitude) of some points on this path (start and end). In this case, the simplest instruments are used: a compass and an eclimeter - a tool for measuring angular height (this is essentially a protractor with a plumb line fixed at its zero point). When such measurements are made at several points, they can be used to construct the atmospheric trajectory of the fireball, and then look for a meteorite near the projection on the ground of its lower end.
Collecting information about fallen meteorites and searching for their samples are exciting tasks for astronomy enthusiasts, but the very formulation of such tasks is largely associated with some luck, luck that is important not to miss. But observations of meteorites can be carried out systematically and bring tangible scientific results. Of course, professional astronomers armed with modern equipment also do this kind of work. For example, they have radars at their disposal, with the help of which meteors can be observed even during the day. And yet, properly organized amateur observations, which also do not require complex technical means, still play a certain role in meteorite astronomy.
Meteorites: falls and finds
It must be said that the scientific world until the end of the 18th century. was skeptical about the very possibility of stones and pieces of iron falling from the sky. Reports of such facts were considered by scientists as manifestations of superstition, because at that time no celestial bodies were known whose debris could fall on Earth. For example, the first asteroids - small planets - were discovered only at the beginning of the 19th century.
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, formed 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.
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
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 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
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 meteorites from the Moon and Mars
Can we really find Moon and Martian rocks on the surface of our own planet? The answer is yes, but they are extremely rare. More than one hundred thousand lunar and approximately thirty Martian meteorites have been discovered on Earth, all of which belong to the achondrite group.
Lunar meteorite
The collision of the surface of the Moon and Mars with other meteorites threw fragments into 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.
Stony-iron meteorites
The least common of the three main types is stony-iron, accounting for less than 2% of all known meteorites. They consist of approximately equal parts of iron-nickel and stone, and are divided into two classes: pallasite and mesosiderite. Stony-iron meteorites formed at the boundary of the crust and mantle of their “parent” bodies.
Example of a stony-iron meteorite
Pallasites are perhaps the most alluring of all meteorites and are definitely of great interest to private collectors. Pallasite consists of an iron-nickel matrix filled with olivine crystals. When olivine crystals are 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 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 area of 2,000 sq. turned into rubble. The blast wave killed animals within a radius of more than 40 km. For several days, artifacts were observed over the territory of central Siberia - luminous clouds and a glow in the sky. According to scientists, this was caused 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 meteorite 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 less than 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.
Events
Scientists believe they have discovered the first meteorite to arrive on Earth from Mercury. The unusual green piece of rock was named NWA 7325. It was discovered in southern Morocco in 2012 and was broken into 35 fragments with a total weight of 345 grams.
Dark green stones were sold to a meteorite dealer Stefan Raelew, who sent samples to University of Washington specialists in meteorites of planetary origin.
The researchers found that these samples contained 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 data obtained by NASA's Messenger spacecraft.
However, the stone contains more calcium silicate than is present 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 as a result of a powerful collision, was thrown into space and eventually landed on the surface of the Earth.
"This sample could be from Mercury, or from a smaller object- said the scientists. – It is very likely that this rock formed as 'foam' in the upper layers of magma."
Where do meteorites come from?
Guests from space meteorites - space rocks, which often fall to the surface of our planet, have always been of interest to 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 surface of the Earth every day - up to 5-6 tons, however, they are generally so small that their decline goes largely unnoticed. Moreover, most meteorites fall into the ocean, where it is not possible to notice their fall or find them later.
Origin of meteorites
Meteorites mainly come to us from Asteroid belts- the area 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 end up on Earth.
Younger meteorites are of Martian or lunar origin, some of them "only" about 180 million years, which by cosmic standards is quite a 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.
Meteorites of asteroid origin
Fragments of the planet Mars that fell to Earth in the form of meteorites have been found more than once, but evidence has been obtained that these meteorites came from Mars only in the 1980s, when gas inclusions were discovered in their composition, corresponding to the gases of the atmosphere of Mars.
When celestial bodies, such as fragments of asteroids or comets, collided with the surface of Mars, they broke off pieces of native rock, which flew into outer space and, ultimately, could end up on the neighboring planet - Earth.
Meteorites of Martian origin
First lunar meteorites were discovered by Americans in the early 1980s in Antarctica. Subsequently, moon rocks 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 soil samples brought from the Moon.
Meteorites of lunar origin
Asteroids, comets, meteors, meteorites are astronomical objects that seem the same to those uninitiated in the basic science of celestial bodies. In fact, they differ in several ways. The properties that characterize asteroids and comets are quite easy to remember. They also have certain similarities: such objects are classified as small bodies and are often classified as space debris. What a meteor is, how it differs from an asteroid or comet, what their properties and origin are, will be discussed below.
Tailed Wanderers
Comets are space objects consisting of frozen gases and rock. They originate in remote regions of the solar system. Modern scientists suggest that the main sources of comets are the interconnected Kuiper belt and the scattered disk, as well as the hypothetically existing
Comets have highly elongated orbits. As they approach the Sun, they form a coma and a tail. These elements consist of evaporating gases such as ammonia, methane), dust and stones. The head of a comet, or coma, is a shell of tiny particles, characterized by brightness and visibility. It has a spherical shape and reaches its maximum size when approaching the Sun at a distance of 1.5-2 astronomical units.
At the front of the coma is the comet's nucleus. As a rule, it has a relatively small size and an elongated shape. At a significant distance from the Sun, the nucleus is all that remains of the comet. It consists of frozen gases and rocks.
Types of comets
The classification of these is based on the periodicity of their revolution around the star. Comets that orbit the Sun in less than 200 years are called short-period comets. Most often they fall into the inner regions of our planetary system from the Kuiper belt or scattered disk. Long-period comets orbit with a period of more than 200 years. Their “homeland” is the Oort cloud.
"Minor planets"
Asteroids are made of hard rock. They are much smaller in size than planets, although some representatives of these space objects have satellites. Most of the small planets, as they were called before, are concentrated in the Main Planet, located between the orbits of Mars and Jupiter.
The total number of such cosmic bodies known in 2015 exceeded 670 thousand. Despite such an impressive number, the contribution of asteroids to the mass of all objects in the Solar System is insignificant - only 3-3.6 * 10 21 kg. This is only 4% of the same parameter of the Moon.
Not all small bodies are classified as asteroids. The selection criterion is diameter. If it exceeds 30 m, then the object is classified as an asteroid. Bodies with smaller dimensions are called meteoroids.
Asteroid classification
The grouping of these cosmic bodies is based on several parameters. Asteroids are grouped together by the characteristics of their orbits and the spectrum of visible light that was reflected from their surface.
According to the second criterion, three main classes are distinguished:
- carbon (C);
- silicate (S);
- metal (M).
Approximately 75% of all asteroids known today belong to the first category. As equipment improves and more detailed research of such objects occurs, the classification expands.
Meteoroids
A meteoroid is another type of cosmic body. These are not asteroids, comets, meteors or meteorites. The peculiarity of these objects is their small size. Meteoroids are located between asteroids and cosmic dust in size. Thus, they include bodies with a diameter of less than 30 m. Some scientists define a meteoroid as a solid body with a diameter from 100 microns to 10 m. According to their origin, they are primary or secondary, that is, formed after the destruction of larger objects.
As the meteoroid enters the Earth's atmosphere, it begins to glow. And here we are already approaching the answer to the question of what a meteor is.
Falling star
Sometimes, among the flickering luminaries in the night sky, one suddenly flashes, describes a small arc and disappears. Anyone who has seen something like this at least once knows what a meteor is. These are “shooting stars” that have nothing to do with real stars. A meteor is actually an atmospheric phenomenon that occurs when small-sized objects (the same meteoroids) enter the air envelope of our planet. The observed brightness of the flare directly depends on the initial dimensions of the cosmic body. If the meteor's brilliance exceeds a fifth, it is called a fireball.
Observation
Such phenomena can only be admired from planets with an atmosphere. Meteors on the Moon or Mercury cannot be observed because they do not have an air envelope.
When conditions are right, shooting stars can be seen every night. It is best to admire meteors in good weather and at a considerable distance from a more or less powerful source of artificial lighting. Also, there should be no Moon in the sky. In this case, up to 5 meteors per hour can be seen with the naked eye. The objects that give rise to these single “shooting stars” revolve around the Sun in very different orbits. Therefore, it is impossible to accurately predict the place and time of their appearance in the sky.
Streams
Meteors, photos of which are also presented in the article, as a rule, have a slightly different origin. They are part of one of several swarms of small cosmic bodies rotating around the star along a certain trajectory. In their case, the ideal viewing period (the time when anyone can quickly figure out what a meteor is by looking at the sky) is pretty well defined.
A swarm of such space objects is also called a meteor shower. Most often they are formed during the destruction of the comet's nucleus. Individual particles of the swarm move parallel to each other. However, from the surface of the Earth, they appear to be coming from a specific small area of the sky. This section is usually called the radiant of the flow. The name of a meteor swarm is usually given by the constellation in which its visual center (radiant) is located, or by the name of the comet whose disintegration led to its appearance.
Meteors, photos of which are easy to obtain if you have special equipment, belong to such large showers as the Perseids, Quadrantids, eta Aquarids, Lyrids, and Geminids. In total, the existence of 64 streams has been recognized to date, and about 300 more are awaiting confirmation.
Heavenly stones
Meteorites, asteroids, meteors and comets are related concepts according to certain criteria. The first are space objects that fell to Earth. Most often, their source is asteroids, less often - comets. Meteorites carry invaluable data about various parts of the solar system beyond Earth.
Most of these bodies that hit our planet are very small in size. The most impressive meteorites in terms of their dimensions leave traces after impact that are quite noticeable even after millions of years. A well-known crater near the city of Winslow in Arizona. The fall of a meteorite in 1908 is believed to have caused the Tunguska phenomenon.
Such large objects “visit” the Earth once every few million years. Most of the meteorites found are quite modest in size, but do not become less valuable for science.
According to scientists, such objects can tell a lot about the formation of the solar system. Presumably, they carry particles of the substance from which the young planets consisted. Some meteorites come to us from Mars or the Moon. Such space wanderers make it possible to learn something new about neighboring objects without the huge costs of distant expeditions.
To remember the differences between the objects described in the article, you can briefly outline the transformation of such bodies in space. An asteroid, consisting of solid rock, or a comet, which is a block of ice, when destroyed, gives rise to meteoroids, which, when entering the planet's atmosphere, burst into meteors, burn up in it, or fall, turning into meteorites. The latter enrich our knowledge of all the previous ones.
Meteorites, comets, meteors, as well as asteroids and meteoroids are participants in continuous cosmic motion. The study of these objects makes a great contribution to our understanding of the structure of the Universe. As equipment improves, astrophysicists are obtaining more and more data about such objects. The relatively recently completed mission of the Rosetta probe clearly demonstrated how much information can be obtained from a detailed study of such cosmic bodies.
Cosmic bodies are constantly falling onto our planet. Some of them are the size of a grain of sand, others can weigh several hundred kilograms and even tons. Canadian scientists from the Ottawa Astrophysical Institute claim that a meteorite shower with a total mass of more than 21 tons falls on Earth per year, and individual meteorites weigh from a few grams to 1 ton.
In this article we will recall the 10 largest meteorites that fell to Earth.
Sutter Mill meteorite, April 22, 2012
This meteorite, named Sutter Mill, appeared near the 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 hot fragments, and exploded over Washington. The power of the explosion was about 4 kilotons of TNT. For comparison, yesterday's power was 300 kilotons of TNT.
Scientists have found that the Sutter Mill meteorite appeared in the early days of its existence, and the progenitor cosmic body was formed over 4566.57 million years ago.
Almost a year ago, on February 11, 2012, about a hundred meteorite stones fell over an area of 100 km in one of the regions of China. The largest meteorite found weighed 12.6 kg. The meteorites are believed to have come from the asteroid belt between Mars and Jupiter.
Meteorite from Peru, September 15, 2007
This meteorite fell in Peru near Lake Titicaca, near the border with Bolivia. Eyewitnesses claimed that at first there was a strong noise, similar to the sound of a falling plane, but then they saw a falling body engulfed in fire.
A bright trail from a white-hot cosmic body entering the Earth's atmosphere is called a meteor.
At the site of the fall, the explosion formed a crater with a diameter of 30 and a depth of 6 meters, from which a fountain of boiling water began to flow. The meteorite probably contained toxic substances, as 1,500 people living nearby began to experience severe headaches.
By the way, most often stone meteorites (92.8%), consisting mainly of silicates, fall to Earth. , was made of iron, according to first estimates.
Kunya-Urgench meteorite from Turkmenistan, June 20, 1998
The meteorite fell near the Turkmen city of Kunya-Urgench, hence its name. Before the fall, residents saw a bright light. The largest part of the meteorite, weighing 820 kg, fell into a cotton field, creating a crater about 5 meters.
This one, over 4 billion years old, has received a certificate from the International Meteor Society and is considered the largest among stone meteorites of all that fell in the CIS and the third in the world.
Fragment of a Turkmen meteorite:
Meteorite Sterlitamak, May 17, 1990
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 a 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 fragment weighing 315 kg:
Largest meteor shower, China, March 8, 1976
In March 1976, the largest meteorite rock shower in the world occurred in the Chinese province of Jilin, 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-ton Jilin (Girin) meteorite.
These are the stones that fell from the sky onto China for 37 minutes:
Meteorite Sikhote-Alin, Far East, February 12, 1947
The meteorite fell in the Far East in the Ussuri taiga in the Sikhote-Alin mountains on February 12, 1947. It fragmented in the atmosphere and fell in the form of iron rain over an area of 10 sq. km.
After the fall, more than 30 craters were formed with a diameter of 7 to 28 m and a depth of up to 6 meters. About 27 tons of meteorite material were collected.
Fragments of “piece of iron” that fell from the sky during a meteor shower:
Goba meteorite, Namibia, 1920
Meet Goba - largest meteorite found! Strictly speaking, it fell about 80,000 years ago. This iron giant weighs about 66 tons and has a volume of 9 cubic meters. fell in prehistoric times and was found in Namibia in 1920 near Grootfontein.
The Goba meteorite is mainly composed of iron and is considered the heaviest of all celestial bodies of this kind that has ever appeared on Earth. It is preserved at a crash site in southwest Africa, Namibia, near Goba West Farm. This is also the largest piece of naturally occurring iron on Earth. Since 1920, the meteorite has shrunk slightly: erosion, scientific research and vandalism have taken their toll: the meteorite has “lost weight” to 60 tons.
The mystery of the Tunguska meteorite, 1908
On June 30, 1908, at about 07 a.m., 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 uninhabited taiga region. The blast wave circled the globe twice and was recorded by observatories around the world.
The power of the explosion 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 knocked down over an area of more than 2,000 square meters. km, window glass in houses was broken several hundred kilometers from the epicenter of the explosion. The blast wave destroyed animals and injured people within a radius of about 40 km. For several days, intense sky glow and luminous clouds were observed from the Atlantic to central Siberia:
But what was it? If it was a meteorite, then a huge crater half a kilometer deep should have appeared at the site of its fall. But none of the expeditions succeeded in finding him...
The Tunguska meteorite is, on the one hand, one of the most well-studied phenomena, on the other hand, one of the most mysterious phenomena of the past century. The celestial body exploded in the air and no remains of it, except for the consequences of the explosion, were found on the ground.
Meteor shower of 1833
On the night of November 13, 1833, a meteor shower occurred over the eastern United States. It continued continuously for 10 hours! During this time, about 240,000 meteorites of various sizes fell to the Earth's surface. The source of the 1833 meteor shower was the most powerful meteor shower known. This shower is now called the Leonids after the constellation Leo, against which it is visible every year in mid-November. On a much more modest scale, of course.
