Infographic by artist Tim Lillis in the form of a picture describing the difference between a comet and an asteroid, meteoroid, meteor and meteorite. Classification of celestial bodies often causes difficulties.
These are typically large boulders of rock that come from the asteroid belt, located between the orbits of Mars and Jupiter. Sometimes their orbits change and some asteroids end up getting closer to the Sun and therefore closer to Earth.
Comets
They are very similar to asteroids, but contain more ice, methane, ammonia and other compounds. They develop fuzzy, cloud-like shells called comas—as well as a tail—as they fly closer to the Sun.
Comets are believed to come from two different places: long-period comets (those with an orbital period of more than 200 years) originate from Oort.
Short-period comets (those with orbital periods less than 200 years) originate from Kuiper.
Meteoroid
Cosmic bodies that are smaller than asteroids, but larger than interplanetary dust are called meteoroids. They are typically less than a kilometer in size and are often only a few millimeters in size.
Most meteoroids that enter the Earth's atmosphere are so small that they evaporate completely and never reach the planet's surface.
When they enter the Earth's atmosphere, they are given the following names:
Meteora
This name is usually used for so-called "shooting stars". The flashes of light we see in the night sky appear when a small piece of interplanetary debris burns up as it passes through the atmosphere. Meteor is a term applied to a flash of light caused by falling space debris.
Bolide
A fireball is a meteor with a brightness of at least −4m, or having noticeable angular dimensions. The International Astronomical Union (MAK) does not have an official definition of "bolide". Particularly bright fireballs are sometimes called superbolides.
Meteorite
Studio photographs of the Chelyabinsk meteorite
If any part of the meteor survives its fall through the atmosphere and onto Earth, it is called meteorite. Although the vast majority of meteorites are very small, their size can range from about a fraction of a gram (the size of a pebble) to 100 kilograms or more.
Wikipedia
Asteroid belt
Classification by composition
stone
chondrites
carbonaceous chondrites
ordinary chondrites
enstatite chondrites
achondrites
iron-stone
pallasites
mesosiderites
iron
Wikipedia
Interesting facts
Registration number 0104197 issued for the work:
Asteroid is a relatively small celestial body solar system, moving in orbit around the Sun. Asteroids are significantly smaller in mass and size than planets and have irregular shape, and do not have an atmosphere, although they may also have satellites.
The term asteroid (from ancient Greek ἀ στεροειδής - “like a star”, from ἀ στήρ - “star” and εῖ̓ δος - “appearance, appearance, quality”) was introduced by William Herschel on the basis that these objects, when observed in telescope looked like points of stars - in contrast to the planets, which when observed through a telescope look like disks. The exact definition of the term "asteroid" is still not established. Until 2006, asteroids were also called minor planets.
The main parameter by which classification is carried out is body size. Asteroids are considered bodies with a diameter of more than 30 m; smaller bodies are called meteoroids.
IN present moment Hundreds of thousands of asteroids have been discovered in the solar system. As of September 6, 2011, there were 84,993,238 objects in the databases, 560,021 had precisely defined orbits and were assigned an official number. 15,615 of them at this time had officially approved names. It is estimated that there may be from 1.1 to 1.9 million objects in the Solar System that are larger than 1 km. Most currently known asteroids are concentrated within the asteroid belt, located between the orbits of Mars and Jupiter.
Wikipedia
Asteroid belt
The orbits of 98% of the numbered asteroids are located between the orbits of Mars and Jupiter. Their average distances from the Sun range from 2.2 to 3.6 astronomical units. They form the so-called main asteroid belt. All asteroids, like large planets, move in forward direction. The periods of their revolution around the Sun are, depending on the distance, from three to nine years. It is not difficult to calculate that linear speed approximately equal to 20 km/s. The orbits of many asteroids are noticeably elongated. Eccentricities rarely exceed 0.4. Most orbits are located close to the ecliptic plane, i.e., to the plane of the Earth's orbit. Tilts are usually a few degrees, but there are exceptions. Thus, the orbit of Ceres has an inclination of 35°, and greater inclinations are also known. If on a model of the Solar System the orbits of asteroids are depicted with wire rings, you will get a loose openwork torus of ellipses chaotically intertwined in space.
Ceres, measuring approximately 975×909 km, was considered the largest asteroid in the Solar System, but since August 24, 2006, it received the status of a dwarf planet. The other two largest asteroids (2) Pallas and (4) Vesta have a diameter of ~500 km. (4) Vesta is the only object in the asteroid belt that can be observed with the naked eye. Asteroids moving in other orbits can also be observed during their passage near the Earth (see, for example, (99942) Apophis).
The total mass of all main belt asteroids is estimated at 3.0–3.6·1021 kg, which is only about 4% of the mass of the Moon. The mass of Ceres is 9.5·1020 kg, that is, about 32% of the total, and together with the three largest asteroids (4) Vesta (9%), (2) Pallas (7%), (10) Hygiea (3%) - 51%, that is, the vast majority of asteroids have an insignificant mass by astronomical standards.
At first, asteroids were given the names of heroes of the Roman and Greek mythology, later the discoverers gained the right to call them whatever they wanted - for example, by their own name. At first, asteroids were given predominantly female names, male names Only asteroids with unusual orbits were received (for example, Icarus, approaching the Sun closer than Mercury). Later, this rule was no longer observed.
Not any asteroid can receive a name, but only one whose orbit has been more or less reliably calculated. There have been cases when an asteroid received a name decades after its discovery. Until the orbit is calculated, the asteroid is given a serial number reflecting the date of its discovery, for example, 1950 DA. The numbers indicate the year, the first letter is the number of the crescent in the year in which the asteroid was discovered (in the example given, this is the second half of February). The second letter indicates the serial number of the asteroid in the specified crescent; in our example, the asteroid was discovered first. Since there are 24 crescents, and English letters- 26, two letters are not used in the designation: I (due to the similarity with one) and Z. If the number of asteroids discovered during the crescent exceeds 24, they return again to the beginning of the alphabet, assigning index 2 to the second letter, at the next return - 3, etc.
After receiving a name, the official naming of the asteroid consists of a number (serial number) and a name - (1) Ceres, (8) Flora, etc.
A meteoroid, or meteoroid, is a celestial body intermediate in size between interplanetary dust and an asteroid. Flying at a tremendous speed (11-72 km/s) into the Earth’s atmosphere, due to friction, it heats up greatly and burns, turning into a luminous meteor or fireball, which can be seen as a “shooting star”. The visible trace of a meteoroid entering the Earth's atmosphere is called a meteor, and a meteoroid falling on the Earth's surface is called a meteorite.
According to the official definition of the International Meteor Organization (IMO), a meteoroid is a solid object moving in interplanetary space, much smaller in size than an asteroid, but much larger than an atom. The British Royal Astronomical Society put forward a different formulation, according to which a meteoroid is a body with a diameter of 100 microns to 10 m. Other sources limit the size of a meteoroid to 50 m.
Cosmic dust is formed in space by particles ranging in size from a few molecules to 0.1 mm. 40 kilotons of cosmic dust settle on planet Earth every year.
Cosmic dust can also be distinguished by its astronomical position, for example: intergalactic dust, interstellar dust, circumplanetary dust, dust clouds around stars and the main components of interplanetary dust in our zodiacal dust complex (observed in visible light as zodiacal light): asteroid dust, comet dust and some minor additions: Kuiper Belt dust, interstellar dust passing through the Solar System, and beta meteoroids.
In the Solar System, dust matter is not evenly distributed, but is concentrated mainly in dust clouds (inhomogeneities) of different sizes. This was installed during a full solar eclipse February 15, 1961 using optical equipment installed on a sounding rocket of the Institute of Applied Geophysics to measure the brightness of the outer corona in the altitude range 60-100 km above the Earth's surface.
A meteorite is a body of cosmic origin that fell on the surface of a large celestial object.
Most meteorites found weigh between a few grams and several kilograms. The largest meteorite found was Goba (which was estimated to weigh about 60 tons). It is believed that 5-6 tons of meteorites fall to the Earth per day, or 2 thousand tons per year.
The existence of meteorites was not recognized by leading academicians of the 18th century, and hypotheses extraterrestrial origin were considered pseudoscientific. It is alleged that the Paris Academy of Sciences in 1790 decided not to consider future reports of rocks falling to the Earth as an impossible phenomenon. In many museums, meteorites (in the terminology of that time - aerolites) were removed from collections so as not to “make museums a laughing stock.”
Academicians V.I. Vernadsky, A.E. Fersman, famous meteorite research enthusiasts P.L. Dravert, L.A. Kulik and many others were involved in the study of meteorites. IN Russian Academy Sciences now have a special committee that supervises the collection, study and storage of meteorites. The committee has a large meteorite collection.
Classification by composition
stone
chondrites
carbonaceous chondrites
ordinary chondrites
enstatite chondrites
achondrites
iron-stone
pallasites
mesosiderites
iron
The most common meteorites are stony meteorites (92.8% of falls). They consist mainly of silicates: olivines (Fe, Mg)2 (from fayalite Fe2 to forsterite Mg2) and pyroxenes (Fe, Mg)2Si2O6 (from ferrosilite Fe2Si2O6 to enstatite Mg2Si2O6).
The vast majority of stony meteorites (92.3% stony, 85.7% total number falls) - chondrites. They are called chondrites because they contain chondrules - spherical or elliptical formations of predominantly silicate composition. Most chondrules are no more than 1 mm in diameter, but some can reach several millimeters. Chondrules are found in a detrital or fine-crystalline matrix, and often the matrix differs from chondrules not so much in composition as in crystal structure. The composition of chondrites almost completely replicates the chemical composition of the Sun, with the exception of light gases such as hydrogen and helium. Therefore, it is believed that chondrites formed directly from the protoplanetary cloud surrounding the Sun, through the condensation of matter and the accretion of dust with intermediate heating.
Achondrites make up 7.3% of stony meteorites. These are fragments of protoplanetary (and planetary?) bodies that have undergone melting and differentiation by composition (into metals and silicates).
Iron meteorites are composed of an iron-nickel alloy. They account for 5.7% of falls.
Iron silicate meteorites have a composition intermediate between stony and iron meteorites. They are relatively rare (1.5% incidence).
Achondrites, iron and iron-silicate meteorites are classified as differentiated meteorites. They presumably consist of matter that has undergone differentiation as part of asteroids or other planetary bodies. Previously, it was believed that all differentiated meteorites were formed as a result of the rupture of one or more large bodies, such as the planet Phaethon. However, an analysis of the composition of various meteorites showed that they were more likely formed from the debris of many large asteroids.
Previously, tektites, pieces of siliceous glass of impact origin, were also isolated. But later it turned out that tektites are formed when a meteorite hits rock rich in silica.
Classification by detection method
falls (when a meteorite is found after observing its fall in the atmosphere);
finds (when the meteorite origin of the material is determined only by analysis).
Wikipedia
Interesting facts
Scientists have studied the Yamato 691 meteorite. This object was discovered in 1969 in Antarctica, becoming one of the first meteorites found on this continent. The scientists' analysis showed that the meteorite is the remains of a celestial body 4.5 billion years old, whose orbit lay between Mars and Jupiter. Using an electron microscope, scientists discovered small inclusions of a new mineral on the surface of the meteorite. The size of the wassonite particles found was 50 by 450 nanometers. According to the researchers, wassonite most likely does not occur on Earth.
A flash drive made from a meteorite was shown in Poland. The manufacturer claims that the body of the gadget is made of African ebony (one of the most valuable types of wood), and decorated with a piece of a real meteorite, diamond and 18-karat gold (or 925 silver). The cost of the gadget is also cosmic. The version with silver inserts will cost the buyer $1,130, while the “gold with meteorite” version costs $2,000.
The discovery of a meteorite is a fairly rare occurrence. The Meteoritics Laboratory reports: “In total, only 125 meteorites have been found on the territory of the Russian Federation over 250 years.”
Murchison (Murchison meteorite) is a carbonaceous meteorite with a total weight of 108 kilograms. Fell near the village of Murchison, Victoria, Australia, September 28, 1969. It is interesting because it contains a large number of organic inclusions. In particular, studies in 2008 showed the presence of nucleic bases. Buildings were damaged during the fall. It also became known because of the fossil particles of filamentous microorganisms discovered in it, reminiscent of lower fungi and retaining details of their cellular structure, as well as the fossilized remains of certain bacteria.
Health and Safety Executive (HSE) in British administration By atomic energy made up the equation. According to it, approximately once every 7 thousand years some unfortunate Briton will be flattened by a celestial body.
Scientists consider Antarctica to be a real repository of meteorites. This inaccessible continent has changed little for many hundreds of thousands of years. Since 1969, researchers from the United States and Japan have collected more than 20,000 meteorite fragments from the Antarctic mountainous regions, where they lay buried under snow layers for thousands of years. In Antarctica, almost all meteorites can be collected, even if this piece of space debris measures a few millimeters in diameter.
Photo: meteorite from Namibia. Named at the auction “The Scream” for its resemblance to the famous painting by Edvard Munch.
Meteorites are small rocky bodies of cosmic origin that fall into the dense layers of the atmosphere (for example, like planet Earth), and some may even fall to the surface of the planet. Before these kinds of celestial guests enter the atmosphere, they are called meteoroids. When they collide with the Earth's air masses, they light up and leave a bright trail, visible to the naked eye, called a meteor. A meteoroid can completely burn up when it falls and never become a meteorite.
By origin, meteorites are fragments of larger cosmic bodies - asteroids, which have their own constant orbits, most of which are located within the Main Asteroid Belt.
The study of meteorites is of great interest. Firstly, many of them consist of matter close to the primary matter of the Solar System, the study of which, undoubtedly, makes it possible to clarify many questions that concern astrophysicists. Secondly, calculating the probabilities of a large meteorite falling to Earth and modeling the consequences of this event is of great importance for drawing up a plan for possible actions in the event of an occurrence. real threat such a disaster.
However, most meteoroids burn up in the upper layers of the atmosphere, and therefore do not pose any danger to the inhabitants of our planet. The fall of large and heavy cosmic rocks onto the Earth does not happen so often, but it still happens. So, in South Africa In prehistoric times, the Goba meteorite landed, found in 1920, called by scientists the heaviest and weighing 60 tons. After this event, our planet was visited by other large messengers from space, the last of them made a lot of noise in Chelyabinsk.
And as this recent Russian experience has shown, predicting the fall of a large rocky body to Earth is not always possible. The reason is simple: dark celestial objects not illuminated by the Sun are not visible through ground-based telescopes, so their entry into the atmosphere is unexpected. Only observing the bright parts helps meteor showers, passing close to us, allowing us to analyze the statistical probabilities of space threats occurring in a particular period.
(Discovery's interpretation of the aftermath of a giant meteorite falling in Pacific Ocean surface of planet Earth, meteorite diameter 500 km)
According to astronomers, approximately once a year a meteorite enters the Earth’s atmosphere, which, upon collision with the surface of the planet, would provoke an explosion with a capacity of 11-12 kilotons of TNT. And once every 15 years, a space wanderer comes to us, threatening to cause much more serious destruction. There is no doubt that in the next 100 years the inhabitants of our
the planet will have to repeatedly witness the fall of large meteorites, unless, of course, scientists and the military establish an effective system of protection against such threats from space.
Asteroids are solid rocky bodies that, like planets, move in elliptical orbits around the sun. But the sizes of these bodies are much smaller than those of ordinary planets, so they are also called minor planets. The diameters of asteroids range from several tens of meters (conventionally) to 1000 km (the size of the largest asteroid Ceres). The term "asteroid" (or "star-like") was coined by the famous 18th-century astronomer William Herschel to describe the appearance of these objects when observed through a telescope. Even with the largest ground-based telescopes, it is impossible to distinguish the visible disks of the largest asteroids. They are observed as point sources of light, although, like other planets, they themselves do not emit anything in the visible range, but only reflect the incident sunlight.
In total, approximately 20,000 asteroids have been discovered to date, of which about 10,000 are registered, that is, they are assigned numbers or even proper names, and the orbits are calculated with great accuracy. Proper names for asteroids are usually assigned by their discoverers, but in accordance with established international rules. At first, when little was known about the minor planets, their names were taken, as for other planets, from ancient Greek mythology. The annular region of space that these bodies occupy is called the main asteroid belt. At average speed At about 20 km/s, main belt asteroids spend one revolution around the Sun from 3 to 9 Earth years, depending on the distance from it.
Information about some asteroids.
1 Ceres is the largest asteroid that was discovered first. It was discovered by Italian astronomer Giuseppe Piazzi on January 1, 1801 and named after the Roman goddess of fertility.
2 Pallas is the second largest asteroid, also the second discovered. This was done by the German astronomer Heinrich Olbers on March 28, 1802.
3 Juno - discovered by K. Harding in 1804.
4 Vesta is the third largest asteroid, also discovered by G. Olbers in 1807. This body has observational evidence of the presence of a basaltic crust covering an olivine mantle, which may be a consequence of the melting and differentiation of its substance. An image of the visible disk of this asteroid was first obtained in 1995 using the American Space telescope them. Hubble, powered by low earth orbit.
8 Flora is the largest asteroid of a large family of asteroids of the same name, numbering several hundred members, which was first characterized by Japanese astronomer K. Hirayama. Asteroids of this family have very close orbits, which probably confirms their joint origin from a common parent body that was destroyed during a collision with some other body.
243 Ida is a main belt asteroid imaged by the Galileo spacecraft on August 28, 1993. These images revealed a small moon of Ida, later named Dactyl. (See Figures 2 and 3).
253 Matilda is an asteroid, images of which were obtained using the NIAR spacecraft in June 1997 (See Fig. 4).
433 Eros is a near-Earth asteroid, images of which were obtained using the NIAR spacecraft in February 1999.
951 Gaspra is a main belt asteroid, which was first imaged by the Galileo interplanetary probe on October 29, 1991 (See Fig. 1).
1566 Icarus is an asteroid approaching the Earth and crossing its orbit, having a very large orbital eccentricity (0.8268).
1620 Geograph is a near-Earth asteroid that is either a binary object or has a very irregular shape. This follows from the dependence of its brightness on the phase of rotation around its own axis, as well as from its radar images.
1862 Apollo - the largest asteroid of the same family of bodies approaching the Earth and crossing its orbit. The eccentricity of Apollo's orbit is quite large - 0.56.
2060 Chiron is an asteroid-comet exhibiting periodic cometary activity (regular increases in brightness near the perihelion of the orbit, that is, at a minimum distance from the Sun, which can be explained by the evaporation of volatile compounds included in the asteroid), moving along an eccentric trajectory (eccentricity 0.3801) between orbits of Saturn and Uranus.
4769 Castalia is a double asteroid with approximately identical (0.75 km in diameter) components in contact. Its radio image was obtained using radar at Arecibo.
4179 Toutatis is a binary asteroid whose components are likely in contact and has dimensions of approximately 2.5 km and 1.5 km. Images of this asteroid were obtained using radars located at Arecibo and Goldstone. Of all the currently known near-Earth asteroids in the 21st century, Toutatis should be at the closest distance (about 1.5 million km, September 29, 2004).
Asteroid Eros
Asteroid Phobos
Asteroid Gaspard
Asteroid Cercera
COMETS
Comets are celestial bodies, consisting of a “head” - a small bright clot-core, which is surrounded by a light, foggy shell consisting of gases and dust. As bright comets approach the Sun, they form a “tail” - a weak luminous stripe, which, as a result of light pressure and the action of the solar wind, is most often directed in the direction opposite to our star.
As it approaches the Sun, the comet will heat up under the influence of the sun's heat so that gas and dust fly away from the surface, forming a bright tail. Despite the fact that comets have been known since ancient times, their serious research only started with late XVIII century, and the first reliable information about their mass, speed, orbital elements, chemical composition became known to astronomers only in the 20th century. But as data on the structure of comets accumulated, more and more questions arose that modern science I am not yet able to answer. One such question is the origin of comets. Currently, we do not know where comets come from or how they are formed. There are two main assumptions about this:
According to the first, comets are born and come to us from some region located outside the solar system. According to the second assumption, comets are born in a hypothetical Oort cloud, located somewhere at the very borders of the Solar system, perhaps beyond the orbits of Uranus or Pluto.
Halley first predicted the appearance of a comet in 1758. Many years after his death, it actually appeared. It was given the name Halley's Comet and was seen back in 1835 and in 1910 and in 1986.
Halley's Comet
METEORS
A meteor is a celestial body that burns up upon entering the atmosphere. Short-term flashes that occur in the earth's atmosphere when rapidly moving tiny solid particles invade it are called meteors (sometimes meteors are incorrectly called “shooting stars”). Relatively large particles can cause a very bright flash
Meteors can be seen on any clear night, and under favorable atmospheric conditions, 5-10 meteors per hour can be seen even with the naked eye. Because these particles revolve around the Sun in random orbits, they can randomly appear in the sky in the most unexpected places. In addition to individual particles, entire swarms of them move around the Sun. Many of them are generated by decaying or broken-up comets. Each meteor swarm orbits the Sun with a constant period, and many of them encounter the Earth at certain periods. During such periods, the number of meteors increases significantly, and then they talk about meteor showers.
METEORITES
Meteorite- a solid body of cosmic origin that fell to the surface of the Earth. Most meteorites found weigh between a few grams and several kilograms. A crater may form at the site of a meteorite impact.
The most ancient terrestrial craters, which undoubtedly arose from the fall of meteorites, were called astroblemes, which in ancient Greek means “star wounds.” Astroblemes are up to two billion years old and are therefore often buried under younger sediments. Their diameter reaches hundreds of kilometers. They are found on all continents of the Earth.
Meteorites are divided into three main classes: iron, stony-iron and stony.
The most common point of view is that M. are fragments minor planets.
Meterites range in size from a few mm up to several m and weigh, respectively, from shares G up to tens T. The largest of the survivors of the split is the Goba iron meteorite, found in South West Africa in 1920, weighs about 60 T. The second largest is the Cape York iron meteorite, found in Greenland in 1818, weighing 34 T. About 35 M. are known, the mass of each of which exceeds 1 T.
Meteor shower
Meteor shower(iron rain, stone rain, fire rain) - multiple falls of meteorites due to its destruction in the process of falling to Earth.
Meteorites. Comets. Asteroids.
A fireball is a rather rare phenomenon - a fireball flying across the sky. This phenomenon is caused by the intrusion of large solid particles called meteoroids into the dense layers of the atmosphere. Moving in the atmosphere, the particle heats up due to braking, and an extensive luminous shell consisting of hot gases forms around it. Fireballs often have a noticeable angular diameter and are visible even during the day. Superstitious people mistook such fireballs for flying dragons with fire-breathing mouths. Due to strong air resistance, the meteor body often splits and falls to Earth in the form of fragments with a roar. The remains of meteoroids that fall to Earth are called meteorites.
A meteoroid body, which is small in size, sometimes evaporates entirely in the Earth's atmosphere. In most cases, its mass decreases greatly during the flight, and only the remnants reach the Earth, usually having time to cool down when the escape velocity has already been extinguished by air resistance. Sometimes a whole meteor shower falls. During flight, meteorites melt and become covered with a black crust. One such “black stone” (Kabba) in Mecca is embedded in the wall of the temple and serves as an object of religious worship.
Meteorites are stone or iron bodies falling to Earth from interplanetary space; They are the remains of meteoroids that were not completely destroyed when moving through the atmosphere.
Meteorite falls on Earth are accompanied by light, sound and mechanical phenomena. A bright fireball called a fireball streaks across the sky, accompanied by a tail and flying sparks. Along the bolide's path, a trail in the sky remains in the form of a smoky stripe, which changes from a straight line to a zigzag shape under the influence of air currents. At night, the car illuminates the area for hundreds of kilometers around. After the car disappears, a few seconds later there are explosion-like impacts caused by shock waves. These waves sometimes cause significant shaking of the ground and buildings.
Meteorites can fall out in cases where the speed of the intruder earth's atmosphere meteoroid body does not exceed 22 km/s and if this body has sufficient mechanical strength. Meeting air resistance, the meteor body slows down, kinetic energy it turns into warmth and light. As a result, the surface layer of the meteorite and the air shell formed around it are heated to several thousand degrees. After boiling, the substance of the meteor body evaporates and is partially sprayed into tiny droplets. Falling almost vertically to the Earth, the fragments of the meteor body cool down and when they reach the ground they turn out to be only warm. They are covered with hardened melting bark. At the site where meteorites fall, depressions are formed, the size and shape of which depend on the mass of the meteorites and the speed of their fall.
The largest meteorite was found in South-West Africa in 1920. This meteorite, called Goba (names are given according to locality, closest to the crash site), iron, its mass is about 60 tons. Such large meteorites rarely fall. As a rule, the masses of meteorites are hundreds of grams or several kilograms.
The largest meteorite is the iron Sikhote-Alin meteorite, which fell in the USSR in 1947. While still in the atmosphere, it split into thousands of pieces and fell to Earth as “iron rain.” When hitting the ground, parts of the meteorite crushed the rocks, forming craters and craters in them. 200 craters and craters with a diameter from 20 cm to 26 m were discovered. The mass of the Sikhote-Alin meteorite is estimated at 70 tons, more than 23 tons were collected.
Meteorites consist of the same chemical elements, which also exist on Earth. These are mainly the following eight elements: iron, nickel, magnesium, silicon, sulfur, aluminum, calcium and oxygen. The remaining elements are found in meteorites in very small quantities. Combining with each other, these elements form various minerals in meteorites, most of which are found on Earth. But there are also meteorites with minerals unknown on Earth.
Iron meteorites consist almost entirely of iron combined with nickel and a small amount of cobalt. Rocky meteorites contain silicates - minerals that are compounds of silicon with oxygen and admixtures of other elements (magnesium, aluminum, calcium, etc.). Nickel iron is also found in stony meteorites in the form of grains scattered throughout the meteorite. Stony-iron meteorites consist of almost equal amounts of stony material and nickel iron.
If you look at the fracture of a stone meteorite, you can see round particles - chondrules. They have the shape of balls with a diameter of 2-5 mm. Tektites - small glass pieces weighing several grams - have been discovered in different places on Earth. It has now been established that tektites are frozen splashes of terrestrial matter, ejected (sometimes over vast distances) during the formation of meteorite craters.
The Earth encounters only those meteor showers whose orbit intersects the Earth's orbit. With a closed swarm, a meteor shower is observed annually around the date when the Earth passes the intersection point. Depending on the thickness of the flow, i.e. Depending on its age, the observation time of meteor showers lasts from several hours to several weeks.
When the Earth encounters a stream of meteor particles, meteors with almost parallel trajectories in the atmosphere are observed (meteor shower). For an earthly observer, due to perspective, such trajectories appear as if emerging from one point in the sky, which is called the radiant. Meteor showers are named by the constellation (Latin name) in which their radiants are located. The most interesting meteor showers: Quadrantids (observed annually on January 3), Lyrids on April 20-24), Aquarids (May 1-9), Perseids (August 5-18), Draconids (October 10), Orionids (October 20-24 ), Leonids (November 15-17), Geminids (December 10-16). Most of the main meteor showers do not have a high spatial density of particles in the swarm, but move towards the Earth and therefore have a large relative speed. As a result, even numerous small particles are capable of generating observable meteors. In the swarms of some weak streams catching up with the Earth, the density of particles is greater than in the swarms of the main meteor showers. Most meteors are called sporadic, i.e. random, but in fact they belong to weak undetected showers. Several times a century, the Earth encounters particularly dense parts of meteor swarms, and then short-term “meteor showers” are observed, lasting 1-2 hours.
It is estimated that about 100 tons of meteoric matter fall to the Earth per day.
