Meteorites and asteroids. asteroids

Meteorites are small stone 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 air masses of the Earth, they light up and leave a bright trail visible to the naked eye, called a meteor. A meteoroid can completely burn out when falling and never become a meteorite.

By origin, meteorites are fragments of larger cosmic bodies - asteroids that have their own permanent orbits, most of which are located within the main asteroid belt.

The study of meteorites is of great interest. First, 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 the Earth and modeling the consequences of this event is of great importance for drawing up a plan of possible actions in the event of a real threat of such a catastrophe.

However, most meteoroids burn up in the upper atmosphere, and therefore do not pose any danger to the inhabitants of our planet. The fall of large and heavy cosmic boulders to 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 having a weight of 60 tons. After this event, other large messengers from outer space visited our planet, the last of them made a lot of noise in Chelyabinsk.

And, as this recent Russian experience has shown, it is not always possible to predict the fall of a large stone body to Earth. The reason is simple: ground-based telescopes do not see dark celestial objects that are not illuminated by the Sun, so their entry into the atmosphere turns out to be unexpected. It helps only to observe the bright parts of meteor showers passing near us, which makes it possible to analyze the statistical probabilities of cosmic threats occurring in a given period.

(Discovery interpretation of the consequences of the fall of a giant meteorite in the Pacific Ocean on the surface of planet Earth, the diameter of the meteorite is 500 km)

According to astronomers, approximately once a year a meteorite enters the Earth's atmosphere, which, when colliding with the planet's surface, would provoke an explosion with a capacity of 11-12 kilotons of TNT. And once every 15 years, a space wanderer flies to us, threatening to cause much more serious destruction. There is no doubt that in the next 100 years the inhabitants of our
planets 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.

On January 1, 1801, the Italian astronomer Giuseppe Piazzi, through his telescope, discovered a new celestial body that looked like a star. It and similar bodies, discovered later, were called asteroids, which means "star-like" (from the Greek words "aster" - star, "oidos" - view).

Over 5,000 asteroids have been discovered so far. Usually these are small, irregularly shaped celestial bodies with a diameter of one to several tens of kilometers.

Of course, asteroids are not stars. Like the planets, they do not emit their own light and revolve around the sun. Therefore, they are also called minor planets.

Asteroids are part of the solar system. Most of them move between the orbits of Mars and Jupiter.

The origin of asteroids has not yet been fully elucidated. For a long time, scientists assumed that these were the remains of some collapsed planet. But recent studies show that, most likely, these are the remains of that “building material” from which all the planets of the solar system known to us were once formed.

Comets

These celestial bodies got their name from the Greek word "cometes", which means "hairy".

Few natural phenomena frightened people like the appearance of a bright comet. It was considered a harbinger of various troubles, such as epidemics, famine, wars.

But gradually scientists accumulated knowledge about these unusual celestial bodies, and now it is known that they are part of the solar system. Comets move in elongated orbits, sometimes approaching the Sun, sometimes moving away from it.

The main part of a comet is a solid core. Its diameter is usually from 1 to 10 km. The core consists of ice, frozen gases and solid particles of some other substances.

As the comet approaches the Sun, the core heats up, and its substances begin to evaporate. A gas envelope forms around the nucleus, and then a long tail appears. A comet's tail can stretch millions of kilometers! It is always directed away from the Sun and consists of gases and fine dust. As a comet moves away from the Sun, its tail and gas envelope gradually disappear.

Over time, under the influence of solar heat, many comets are completely destroyed. Their particles are scattered in outer space.

Comets visible to the naked eye are rare.
But with the help of telescopes, scientists observe them quite often.

Meteora

A huge amount of so-called cosmic dust moves in interplanetary space. In most cases, these are the remains of collapsed comets. From time to time they burst into the Earth and flare up, sweeping across the black sky with a bright luminous line: it seems

that a star is falling. These flashes of light are called meteors (from the Greek word "meteoros" - floating in the air).

Cosmic particles are heated as a result of friction against the atmosphere, flare up and burn out. This usually happens at an altitude of 80-100 km above the Earth.

meteorites

In addition to cosmic dust, larger bodies also move in interplanetary space, mainly asteroid fragments. Getting into the Earth's atmosphere, they do not have time to burn out in it. Their remains fall on . Space bodies that have fallen to Earth are called meteorites. Meteorites are divided into three major classes: stony, iron, and stony-iron.

The fall of large meteorites to Earth is a rather rare phenomenon. Usually their mass ranges from hundreds of grams to several kilograms. The largest meteorite ever found weighed over 60 tons.

Scientists are carefully studying these space "aliens", as they allow us to judge the composition of celestial bodies, the processes taking place in space.

Mysterious Neighbors of the Sun

The largest of the asteroids - Ceres - has a diameter of about 1000 km. He was the first to open. The total mass of all asteroids is about 20 times less than the mass of the moon. Despite this, they pose some danger to our planet. Scientists do not rule out that one of the asteroids may collide with the Earth. This would lead to a terrible disaster. Ways are now being developed to protect the Earth from this danger.

The most famous comet, Halley's Comet, approaches the Sun once every 76 years. At this time, it flies relatively close to the Earth, and it can be observed with the naked eye. The last time people saw this comet was in 1986. Its next appearance is expected in 2062.

About 2,000 meteorites fall to Earth every year. The fall of large meteorites is accompanied by an explosion. A meteorite crater forms at the site of the explosion. One of the largest meteorite craters is located in the USA (Arizona), its diameter is 1200 m, the depth is almost 200 m.

1. In which part of the solar system do most asteroids travel?
2. What is the structure of a comet? What is its core made of?
3. How does the appearance of a comet change as it orbits?
4. What is a meteor; meteorite?

The solar system consists of asteroids and comets. Space dust particles and larger bodies - fragments of asteroids - move in interplanetary space. Flashes of light that occur when particles of cosmic dust burn in the earth's atmosphere are called meteors, and cosmic bodies that have fallen to Earth are called meteorites.

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Minor planets – asteroids (gr. asterodeis - star-like) have nothing in common with stars, but are named so only because they are visible through a telescope as point objects. The history of the discovery of small planets is interesting. By the end of the XVIII century. the empirical law of planetary distances (the so-called Titius-Bode rule) was known, according to which there should have been another unknown planet between Mars and Jupiter. The search for it led the astronomer Piazzi to the discovery in 1801 of the planet Ceres with a diameter of 1003 km. The discovery of three more planets: Pallas - 608 km, Juno - 180 km and Vesta - 538 km - was unexpected. In recent years, asteroids up to 1 km in diameter have been discovered, and their total number reaches several thousand. Since asteroids move, long photographic exposures show them as bright white lines against the black background of the starry sky.

Observations have shown that asteroids have an irregular polyhedral shape and move along orbits of various shapes - from circles to highly elongated ellipses; the vast majority of them (98%) are enclosed between the orbits of Mars and Jupiter (“the main asteroid belt”), but the asteroid Icarus approaches the Sun closer than Mercury, and some move away to Saturn. The orbits of most asteroids are concentrated near the plane of the ecliptic; their circulation periods are from 3.5 to 6 years; it is assumed that they rotate around their axes (based on the periodic change in apparent brightness). According to the material composition, stone, carbonaceous and metallic asteroids are distinguished.

The total mass of all asteroids is estimated at 0.01 Earth masses. Their general attraction does not cause perceptible perturbations in the motion of Mars and other planets.

The orbits of some asteroids intersect with the orbit of the Earth, but the probability of both the Earth and the asteroid being at the same point and colliding is extremely small. It is believed that 65 million years ago an asteroid-type celestial body fell to Earth in the area of ​​the Yucatan Peninsula and its fall caused clouding of the atmosphere and a sharp decrease in the average annual air temperature, which affected the Earth's ecosystem.

Currently, astronomers are concerned about the unusual "invasion" of large celestial bodies in the vicinity of the planets of the solar system. So, in May 1996, two asteroids flew by at a short distance from the Earth. Many experts suggest that the solar system fell into a kind of plume of large celestial bodies formed outside our system, and therefore believe that, along with the nuclear threat, the number one danger for our planet has become the danger emanating from asteroids. A new important problem has arisen - the creation of space protection of the Earth from asteroids, which should include both ground-based and space-based facilities, including those deployed in outer space. The creation of such a system should be carried out on an international basis.

On the other hand, the increase in the number of visible asteroids can be explained by the increase in the amount of astronomical information in recent years, after observations were transferred from the Earth's surface to the near space.

On the question of the origin of asteroids, two directly opposite points of view were expressed. According to one hypothesis, asteroids are fragments of a large planet (it was called Phaeton), which was located between Mars and Jupiter at the site of the main asteroid belt and split as a result of a cosmic catastrophe due to the powerful gravitational influence of Jupiter. According to another hypothesis, asteroids are protoplanetary bodies that arose due to the thickening of the dusty environment, which could not unite into a planet due to the perturbing action of Jupiter. In both cases, the "culprit" is Jupiter.

Comets (gr. cometes - long-haired) - small bodies of the solar system moving in highly elongated elliptical or even parabolic orbits. Some comets have perihelion near the Sun and aphelion outside Pluto. The movement of comets in orbits can be both direct and reverse. The planes of their orbits lie in different directions from the Sun. The periods of revolution of comets are very different: from several years to many thousands of years. A tenth of the known comets (about 40) have appeared repeatedly; they are called periodic.

Comets have heads and tails. The head consists of a hard core and coma. The core is an ice conglomerate of frozen gases (steam, carbon dioxide, methane, ammonia, etc.) with an admixture of refractory silicates, carbon dioxide and metal particles - iron, manganese, nickel, sodium, magnesium, calcium, etc. It is assumed that the core and organic molecules. Comet nuclei are small, their diameter is from several hundred meters to several (50 - 70) kilometers. Coma is a gas-dust environment (hydrogen, oxygen, etc.) that glows when approaching the Sun. Near the perihelion from the nucleus of a comet, under the influence of solar heat and corpuscular flows, "evaporation" (sublimation) of frozen gases occurs and a luminous tail of a comet is formed, sometimes more than one. It consists of rarefied gases and small solid particles and is directed away from the Sun. The length of the tails reaches hundreds of millions of kilometers. The Earth has more than once fallen into the tails of comets, for example, in 1910. This then caused great concern for people, although falling into comet tails does not pose any danger to the Earth: they are so rarefied that the admixture of poisonous gases contained in comet tails (methane, cyan), in the atmosphere is imperceptible.

Among periodic comets, the most interesting is Halley's comet, named after the English astronomer who discovered it in 1682 and calculated the period of revolution (about 76 years). It was in its tail that the Earth ended up in 1910. The last time it appeared in the sky in April 1986, passing at a distance of 62 million km from the Earth. Careful studies of the comet using spacecraft showed that the icy core of the comet is a monolithic irregularly shaped body about 15x7 km in size, around which a giant hydrogen corona with a diameter of 10 million km was discovered.

Comets are short-lived celestial bodies, because as they approach the Sun, they gradually “melt” due to the intense outflow of gases or disintegrate into a swarm of meteors. The meteor matter is subsequently more or less evenly distributed over the entire orbit of the parent comet. In this regard, the history of the periodic (about 7 years) comet Biela, discovered in 1826, is interesting. Twice after the discovery, astronomers observed its appearance, and for the third time, in 1846, they managed to fix its division into two parts, which during subsequent returns became more and more distant from each other. Then the meteor matter of the comet was stretched over the entire orbit, at the intersection of which the Earth observed a plentiful "rain" of meteors.

No exact data has been recorded that the Earth has ever collided with the nucleus of a comet. No more than five comets enter the Earth's orbit every year. However, there is a version that the famous Tunguska "meteorite", which fell in 1908 in the Podkamennaya Tunguska river basin, near the village of Vanavara, is a small (about 30 m) fragment of the Encke comet nucleus, which exploded as a result of thermal heating in the atmosphere, and "ice " and solid impurities "evaporated". At the same time, an explosive air wave knocked down a forest in an area within a radius of 30 km.

In 1994, scientists observed the fall of the comet Shoemaker-Levy on Jupiter. At the same time, it broke up into dozens of fragments 3–4 km in diameter, which flew one after another at a tremendous speed of about 70 km/s, exploded in the atmosphere and evaporated. The explosions produced a giant hot cloud 20,000 km in size and 30,000 °C in temperature. The fall of such a comet to Earth would have ended in a cosmic catastrophe for it.

It is believed that the "comet cloud" surrounding the Sun was formed along with the solar system. Therefore, by studying the substance of comets, scientists obtain information about the primary material from which planets and satellites were formed. In addition, assumptions have appeared about the "participation" of comets in the origin of life on Earth, since radiospectroscopic methods have proved the presence of complex organic compounds (formaldehyde, cyanoacetylene, etc.) in comets and meteorites.

Meteora, usually called “shooting stars”, these are the smallest (mg) solid particles that fly into the atmosphere at a speed of up to 50 - 60 km / s, heat up due to air friction up to several thousand degrees Celsius, ionize gas molecules, causing them to radiate light, and evaporate at an altitude of 80-100 km above the earth's surface. Sometimes a large and exceptionally bright fireball appears in the sky, which can crack and even explode during flight. This meteor is called car. A similar fireball exploded on September 25, 2002 in the Irkutsk region, between the villages of Mama and Bodaibo. In the sky, both single meteors randomly appearing in the sky, and groups of meteors in the form meteor showers, within which the particles move parallel to each other, although in perspective they seem to fly from a single point in the sky, called radiant. Meteor showers are named after the constellations in which their radiants are located. The Earth crosses the orbit of the Perseids around August 12, Orionids - October 20, Leonids - November 18, etc. Meteor showers move along the orbits of those asteroids or comets, as a result of the decay of which they are formed. The orbits of meteor showers are carefully studied for the safety of spacecraft and vehicles.

meteorites(from Greek. meteora - celestial phenomena) are called large meteoroids that fall to Earth. About two thousand meteorites with a total mass of about 20 tons fall on the earth's surface every year. They are fragments of a rounded-angular shape, usually covered with a thin black melting crust with numerous cells from the drilling action of air jets. According to their structure, they are of three classes: iron, consisting mainly of nickel iron, stone, which are predominantly silicate minerals, and iron-stone, consisting of a mixture of these substances. There are two groups of stony meteorites: chondrites (granular meteorites) and achondrites (earthy meteorites). Stony meteorites predominate (Fig. 3). Physico-chemical analysis of meteorites indicates that they consist of chemical elements and their isotopes known on Earth, which confirms the unity of matter in the Universe.

Rice. 3. a - the relative frequency of fallout of meteorites of different classes (according to J. Bud); b – mineral composition of a typical chondrite (according to V. E. Khain)

The largest Goba meteorite, 2.75x2.43 m in size and weighing 59 tons, was found in southwestern Africa; it is iron. The Sikhote-Alin meteorite (fell in 1947) split into thousands of pieces in the air and fell to Earth like an "iron rain". The total weight of the collected fragments is about 23 tons, they created 24 impact craters from 8 to 26 m in diameter. The Kaaba meteorite (“Black Stone”) is stored in the mosque of Mecca in Saudi Arabia and serves as an object of worship for Muslims. Many meteorites have been found in Antarctica, they are also found in the sediments of the World Ocean bed.

At the dawn of the Earth's existence, when there was still a lot of unused material in the solar system, and the Earth's atmosphere - protection from meteorites - was still very thin, the number of meteorites that bombarded the Earth was huge and its surface resembled the face of the moon. Over time, most of the craters were destroyed by tectonic and exogenous processes, but many of them still survived in the form of ring-shaped geological structures called astroblems("star scars"). They are especially well visible from space. They reach tens of kilometers in diameter. The study of meteorites makes it possible to judge the structure and properties of celestial bodies and completes our knowledge of the internal structure of the Earth.

Years in Chelyabinsk led to many questions.

According to the data, a meteorite with a diameter of about 15 meters weighing 7,000 tons entered the atmosphere at an angle of about 20 degrees at a speed of 65,000 km per hour. It passed through the atmosphere for 30 seconds before breaking apart. This resulted in an explosion about 20 km above the ground, producing a shock wave of 300 kilotons. More than 1,000 people were injured as a result.

Fragments of a meteorite were recently found near Lake Chebarkul.

Events such as the fall of a meteorite once again remind us of the potential danger that lies in outer space. What is a meteorite, asteroid and comet? How often do these events happen and can they be prevented?

Meteor falling

Meteor, meteorite, meteoroid - what's the difference?

A meteor is the scientific name for a "shooting star" and is a luminous trail from space debris that ends up in the Earth's atmosphere. They can be small as a grain of sand and large meteoroids up to 10-30 meters in size. As a rule, they burn up in the atmosphere, and those that fall to Earth are called meteorites.

How often does a meteorite fall to Earth?

Small drops happen every few months, but we don't see them. The fact is that two-thirds of the Earth is oceans, so we often miss these events. Such large objects, like the one that exploded in Chelyabinsk, are much rarer, about every five years. So in 2008, a similar event was observed in Sudan, but no one was hurt.

A meteorite flies to Earth: can it be prevented?

As a rule, such meteoroids go unnoticed, since most telescopes are aimed at identifying huge potentially dangerous asteroids. So far, there is no weapon capable of preventing the fall of a meteorite or an asteroid.

asteroid impact

The Chelyabinsk meteorite was the largest since the 1908 Tunguska meteorite in Siberia, which was caused by an object roughly the size of asteroid 2012 DA14 that flew safely at a minimum distance of 27,000 km from Earth on February 15, 2013.

Passage of an asteroid: What is an asteroid?

An asteroid is a celestial body that orbits around the Sun, usually between Mars and Jupiter. Asteroids are also called space debris or fragments left over from the formation of the solar system.

Due to collisions, some asteroids are ejected from the main belt, and they find themselves on a trajectory that intersects the Earth's orbit.

Large asteroids are called planetodids, and objects smaller than 30 meters are called meteoroids.

Asteroid Sizes: How Big Can They Be?

Asteroid 2012 DA14, which flew by on Friday, was about 45 meters in diameter and weighed about 130,000 tons.. Scientists believe that there are about 500,000 asteroids the size of asteroid 2012 DA14. However, less than one percent of asteroids have been discovered so far.

The supposed asteroid that killed the dinosaurs 65 million years ago is believed to have been around 10-15 km in diameter. If an asteroid of this magnitude were to fall today, it would wipe out all modern civilization from the face of the earth.

Statistically, asteroids larger than 50 meters fall to Earth once a century. Asteroids larger than 1 km in diameter can collide every 100 thousand years.

comet fall

2013 can be called the year of comets, as we will be able to observe two of the brightest comets in history at once.

What is a comet?

Comets are celestial bodies in our solar system made up of ice, dust and gas. Most of them are in the Oort Cloud - a mysterious region of the outer edge of the solar system. Periodically, they pass close to the Sun and begin to evaporate. The solar wind turns this steam into a huge tail.

Most comets are too far from the Sun and Earth to be seen with the naked eye. Bright comets appear every few years, even more rarely two comets appear at once in one year.

Comet 2013

Comet PANSTARRS

Comet PANSTARRS or C/2011 L4 was discovered in June 2011 using the Pan-STARRS 1 telescope located atop Haleakala in Hawaii. In March 2013, the comet will be closest to the Sun (at 45,000 km) and the Earth (164 million km).

Although comet PANSTARRS was a dim and distant object at the time of its discovery, it has steadily become brighter ever since.

Comet ISON, discovered in 2012

When can you watch? Mid November - December 2013

Comet ISON or C/2012 S1 was discovered on September 21, 2012 by two astronomers Vitaly Nevsky and Artem Novichonok using a telescope International Scientific Optical Network(ISON).

Orbital calculations have shown that Comet ISON will make its closest approach to the Sun at a distance of 1.2 million km. The comet will be bright enough to be seen in the sky on its closest approach to the Sun in the first weeks of November.

It is believed that this comet will be brighter than the full moon, and it will be visible even during the day.

Comet impact

Can a comet hit the Earth? It is known from history that the comet Shoemaker-Levy 9 collided with Jupiter in July 1994, and it became first comet impact observed by scientists. Given that it happened on an uninhabited planet, the event was rather an interesting example of the destructive forces of the universe. However, if this had happened on Earth, history would have taken a very different turn.

Comets and asteroids

Comets differ from asteroids in their unusually elongated, elliptical orbit, meaning they travel very long distances from the Sun. In contrast, asteroids remain within the asteroid belt.

Fortunately, it takes many years to orbit a comet. A comet approaches Earth once every 200,000 years.. To date, it is not known about comets that pose a threat to our planet in the near future.

Comets with a period of more than 200,000 years have a less predictable orbit and, although there is little chance of a collision with the Earth, they should not be forgotten.

Minor planets, or asteroids, orbit between Mars and Jupiter and are invisible to the naked eye. The first minor planet was discovered in 1801, and by tradition it was named one of the names of Greco-Roman mythology - Ceres. Other minor planets were soon found, named Pallas, Vesta and Juno. With the use of photography, ever weaker asteroids began to be discovered. Currently, more than 2000 asteroids are known. Perhaps the asteroids arose because the substance for some reason failed to gather into one large body - the planet. For billions of years, asteroids collide with each other. This idea is suggested by the fact that a number of asteroids are not spherical, but irregular in shape. The total mass of asteroids is estimated at only 0.1 of the mass of the Earth.

The brightest asteroid - Vesta is never brighter than the 6th magnitude. The largest asteroid is Ceres. Its diameter is about 800 km, and beyond the orbit of Mars, even the strongest telescopes on such a small disk cannot see anything. The smallest known asteroids are only about a kilometer in diameter (Fig. 63). Of course, asteroids don't have an atmosphere. In the sky, small planets look like stars, which is why they were called asteroids, which means “star-like” in ancient Greek. They differ from stars only in the loop-like movement characteristic of the planets against the background of the starry sky. The orbits of some asteroids have unusually large eccentricities, as a result of which at perihelion they come closer to the Sun than Mars and even the Earth (Fig. 64). Icarus comes closer to the Sun than Mercury. In 1968, Icarus approached the Earth almost 10 times closer than Mars, but its negligible attraction had no effect on the Earth. From time to time, Hermes, Eros and other small planets come close to the Earth.

2. Fireballs and meteorites.

A rather rare phenomenon is called a bolide - a fireball flying across the sky (Fig. 65). This phenomenon is caused by the invasion of large meteoroids into the dense layers of the atmosphere, surrounded by an extensive shell of hot gases and particles formed during heating due to deceleration in the atmosphere. Fireballs often have a noticeable angular diameter in Vio of the visible diameter of the Moon and are visible even during the day. Superstitious people mistook such fireballs for flying dragons with a fire-breathing mouth. From strong air resistance, the meteoroid often breaks up and falls to the Earth with a roar in the form of fragments. A body that falls to Earth is called a meteorite.

A meteorite, which is small in size, sometimes completely evaporates in the Earth's atmosphere. In most cases, the mass of a meteorite decreases greatly during the flight. Only the remnants of a meteorite reach the Earth, usually having time to cool down when its cosmic velocity is already extinguished by air resistance. Drops out sometimes

Rice. 63. The size of one of the smallest known asteroids in comparison with the building of Moscow State University.

Rice. 64. Orbits of some asteroids with a large orbital eccentricity.

whole meteor shower. During the flight, meteorites melt and become covered with a black crust (Fig. 66). One such "black stone" in Mecca is built into the wall of the temple and serves as an object of religious worship.

There are three types of meteorites: stone, iron and iron-stone. Sometimes meteorites are found many years after they fall. Iron meteorites are especially found. In the USSR, a meteorite is the property of the state and is subject to delivery to museums for study. The age of meteorites is determined by the content of radioactive elements and lead. It is different, but the oldest meteorites are 4.5 billion years old.

Some of the largest meteorites explode at a high falling speed and form meteorite craters resembling those of the moon. The largest well-studied crater is located in Arizona (USA) (Fig. 67). Its diameter is 1200 m and its depth is 200 m.

Rice. 65. Flight of the fireball

Rice. 66. Iron meteorite.

Rice. 67. Arizona meteorite crater.

This crater appeared, apparently, about 5000 years ago. Traces of even larger and older meteorite craters have been found. All meteorites are members of the solar system.

Judging by the fact that the number of asteroids increases with decreasing size, and by the fact that many small asteroids have already been discovered that cross the orbit of Mars, it can be assumed that meteorites are very small asteroids with orbits that cross the orbit of the Earth. The structure of some meteorites indicates that they were subjected to high temperatures and pressures and, therefore, could exist in the interior of a collapsed planet or a large asteroid.