Asteroids

Asteroids. General information

Fig.1 Asteroid 951 Gaspra. Credit: NASA

Besides 8 major planets part solar system included a large number of smaller cosmic bodies similar to planets - asteroids, meteorites, meteors, Kuiper belt objects, “Centaurs”. This article will focus on asteroids, which until 2006 were also called minor planets.

Asteroids are bodies natural origin, orbiting the Sun under the influence of gravity, not related to large planets, having dimensions greater than 10 m and not exhibiting cometary activity. Most asteroids lie in the belt between the orbits of the planets Mars and Jupiter. Within the belt there are more than 200 asteroids whose diameter exceeds 100 km and 26 with a diameter of more than 200 km. The number of asteroids with a diameter of more than one kilometer, according to modern estimates, exceeds 750 thousand or even a million.

Currently, there are four main methods for determining the size of asteroids. The first method is based on observing asteroids through telescopes and determining the amount of light reflected from their surface. sunlight and released heat. Both values ​​depend on the size of the asteroid and its distance from the Sun. The second method is based on visual observation of asteroids as they pass in front of a star. The third method involves using radio telescopes to image asteroids. Finally, the fourth method, which was first used in 1991 by the Galileo spacecraft, involves studying asteroids at close range.

Knowing the approximate number of asteroids within the main belt, they the average size and composition, you can calculate their total mass, which is 3.0-3.6 10 21 kg, which is 4% of the mass natural satellite Lands of the Moon. Moreover, the 3 largest asteroids: 4 Vesta, 2 Pallas, 10 Hygeia account for 1/5 of the total mass of the main belt asteroids. If we also take into account the mass of the dwarf planet Ceres, which was considered an asteroid until 2006, then it turns out that the mass of more than a million remaining asteroids is only 1/50 Moon mass, which by astronomical standards is extremely small.

average temperature asteroids -75°C.

History of observation and study of asteroids

Fig.2 The first discovered asteroid Ceres, later classified as a minor planet. Credit: NASA, ESA, J.Parker (Southwest Research Institute), P.Thomas ( Cornell University), L. McFadden (University of Maryland, College Park), and M. Mutchler and Z. Levay (STScI)

First discovered small planet became Ceres, discovered by the Italian astronomer Giuseppe Piazzi in the Sicilian city of Palermo (1801). At first Giuseppe thought that the object he saw was a comet, but after identifying German mathematician Carl Friedrich Gauss's study of the orbital parameters of a cosmic body makes it clear that it is most likely a planet. A year later, according to the Gauss ephemeris, Ceres is found by the German astronomer G. Olbers. The body, named Ceres by Piazzi, in honor of the ancient Roman goddess of fertility, was located at the distance from the Sun at which, according to the Titius-Bode rule, a large planet of the solar system should have been located, the search for which was carried out by astronomers with late XVIII century.

In 1802, the English astronomer W. Herschel introduced new term"asteroid". Herschel called asteroids space objects, which, when observed through a telescope, looked like dim stars, unlike planets, which, when visually observed, had the shape of a disk.

In 1802-07. The asteroids Pallas, Juno and Vesta were discovered. Then came an era of calm lasting about 40 years, during which not a single asteroid was discovered.

In 1845, German amateur astronomer Karl Ludwig Henke, after 15 years of searching, discovered the fifth main belt asteroid - Astraea. From now on, a simply global “hunt” begins for asteroids of all astronomers of the world, because before Henke's opening scientific world it was believed that there were only four asteroids and eight years of fruitless searches during 1807-15. it would seem that they only confirm this hypothesis.

In 1847, the English astronomer John Hind discovered the asteroid Iris, after which until now at least one asteroid has been discovered every year (except 1945).

In 1891, the German astronomer Maximilian Wolf began to use the astrophotography method to detect asteroids, in which asteroids left short light lines in photographs with a long exposure period (illumination of the photo layer). By using this method Wolf was able to detect 248 asteroids in a short period of time, i.e. only slightly less than what was discovered fifty years before.

In 1898, Eros was discovered, approaching the Earth at a dangerous distance. Subsequently, other asteroids approaching the earth's orbit were discovered, and they were identified as a separate class of Amurs.

In 1906, Achilles was discovered sharing an orbit with Jupiter and following in front of it at the same speed. All newly discovered similar objects began to be called Trojans in honor of the heroes of the Trojan War.

In 1932, Apollo was discovered - the first representative of the Apollo class, which at perihelion approaches the Sun closer than the Earth. In 1976, Aten was discovered, which laid the foundation for a new class - aten, the magnitude of the major axis of the orbit is less than 1 AU. And in 1977, the first small planet was discovered that never approaches the orbit of Jupiter. Such small planets were called Centaurs as a sign of their proximity to Saturn.

In 1976, the first near-Earth asteroid of the Aten group was discovered.

In 1991, Damocles was found, which has a very elongated and highly inclined orbit, characteristic of comets, but does not form a cometary tail when approaching the Sun. Such objects began to be called Damocloids.

In 1992, it was possible to see the first object from the belt of minor planets predicted by Gerard Kuiper in 1951. He was named 1992 QB1. After this, larger and larger objects began to be found in the Kuiper Belt every year.

In 1996 came new era in the study of asteroids: the US National Aeronautics and Space Administration sent Eros to the asteroid spacecraft"NEAR spacecraft", which was supposed to not only photograph the asteroid as it flew past it, but also become artificial satellite Eros, and subsequently land on its surface.

On June 27, 1997, on its way to Eros, NEAR flew at a distance of 1212 km. from the small asteroid Matilda, taking over 50m of black and white and 7 color images covering 60% of the asteroid's surface. Matilda's magnetic field and mass were also measured.

At the end of 1998, due to the loss of communication with the device, the time for entering Eros orbit was postponed for 27 hours from January 10, 1999 to February 14, 2000. At the appointed time, NEAR entered a high orbit of the asteroid with a periapsis of 327 km and an apocenter of 450 km. A gradual decline in orbit begins: on March 10, the device entered a circular orbit at an altitude of 200 km, on April 11, the orbit decreased to 100 km, on December 27, a decrease occurred to 35 km, after which the mission of the device entered the final stage with the goal of landing on the surface of an asteroid. During the decline stage - on March 14, 2000, "NEAR spacecraft" was renamed in honor of the American geologist and planetary scientist Eugene Shoemaker, who tragically died in a car accident in Australia, to "NEAR Shoemaker".

On February 12, 2001, NEAR began braking, which lasted 2 days, ending with a soft landing on the asteroid, followed by photographing the surface and measuring the composition of the surface soil. On February 28, the mission of the device was completed.

In July 1999, the Deep Space 1 spacecraft from a distance of 26 km. explored the Braille asteroid, collecting a large amount of data on the asteroid's composition and obtaining valuable images.

In 2000, the Cassini-Huygens spacecraft photographed the asteroid 2685 Masurski.

In 2001, the first Aten was discovered, which does not cross earth's orbit, as well as Neptune's first Trojan.

On November 2, 2002, NASA's Stardust spacecraft photographed the small asteroid Annafranc.

On May 9, 2003, the Japan Aerospace Exploration Agency launched the Hayabusa spacecraft to study the Itokawa asteroid and deliver soil samples from the asteroid to Earth.

On September 12, 2005, Hayabusa approached the asteroid at a distance of 30 km and began research.

In November of the same year, the device made three landings on the surface of the asteroid, as a result of which the Minerva robot, designed for photographing individual dust grains and shooting close panoramas of the surface, was lost.

On November 26, another attempt was made to lower the apparatus to collect soil. Shortly before landing, communication with the device was lost and restored only 4 months later. Whether the soil sampling was possible remained unknown. In June 2006, JAXA reported that Hayabusa was likely to return to Earth, which happened on June 13, 2010, when a capsule containing samples of asteroid particles was dropped at the Woomera test site in southern Australia. Having examined soil samples, Japanese scientists found that the Itokawa asteroid contains Mg, Si and Al. On the surface of the asteroid there is a significant amount of pyroxene and olivine minerals in a ratio of 30:70. Those. Itokawa is a fragment of a larger chondritic asteroid.

After the Hayabusa spacecraft, asteroids were also photographed by the New Horizons spacecraft (June 11, 2006 - asteroid 132524 APL) and the Rosetta spacecraft (September 5, 2008 - photographing asteroid 2867 Steins, July 10, 2010 - asteroid Lutetia). In addition, on September 27, 2007, the automatic interplanetary station “Dawn” launched from the spaceport at Cape Canaveral, which will enter a circular orbit around the asteroid Vesta this year (presumably on July 16). In 2015, the device will reach Ceres - the most large object in the main asteroid belt - after working in orbit for 5 months, it will complete its work...

Asteroids vary in size, structure, orbital shape, and location in the solar system. Based on the characteristics of their orbits, asteroids are classified into separate groups and families. The first ones are formed by fragments of larger asteroids, and therefore, the semimajor axis, eccentricity and orbital inclination of asteroids within the same group almost completely coincide. The second group combine asteroids with similar orbital parameters.

Currently, more than 30 families of asteroids are known. Most asteroid families are located in the main belt. Between the main concentrations of asteroids in the main belt there are empty areas known as Kirkwood gaps or hatches. Similar areas arise as a result gravitational interaction Jupiter due to which the orbits of asteroids become unstable.

There are fewer groups of asteroids than families. In the description below, groups of asteroids are listed in order of their distance from the Sun.

Fig.3 Groups of asteroids: white - main belt asteroids; green ones beyond the outer border of the main belt are the Trojans of Jupiter; orange - Hilda's group. . Source: wikipedia

Closest to the Sun is the hypothetical belt of Vulcanoids - small planets whose orbits lie completely inside the orbit of Mercury. Computer calculations show that the region lying between the Sun and Mercury is gravitationally stable and, most likely, small celestial bodies exist there. Their practical detection is complicated by their proximity to the Sun, and so far not a single Vulcanoid has been discovered. Craters on the surface of Mercury indirectly support the existence of volcanoids.

The next group is the Aten, minor planets named after the first representative, discovered by American astronomer Eleanor Helin in 1976. For atons, the semimajor axis of their orbit is less than the astronomical unit. Thus, for most of their orbital path, the Atons are closer to the Sun than the Earth, and some of them never cross the Earth's orbit at all.

More than 500 atons are known, of which only 9 have their own names. Atons are the smallest of all asteroid groups: most of them are less than 1 km in diameter. The largest aton is Cruithna, with a diameter of 5 km.

Between the orbits of Venus and Jupiter, groups of small asteroids Amur and Apollo stand out.

Cupids are asteroids lying between the orbits of Earth and Jupiter. Cupids can be divided into 4 subgroups, differing in the parameters of their orbits:

The first subgroup includes asteroids lying between the orbits of Earth and Mars. These include less than 1/5 of all cupids.

The second subgroup includes asteroids whose orbits lie between the orbit of Mars and the main asteroid belt. The long-standing name for the entire group, asteroid Amur, also belongs to them.

The third subgroup of cupids unites asteroids whose orbits lie within the main belt. About half of all cupids belong to it.

The last subgroup includes a few asteroids lying outside the main belt and penetrating beyond the orbit of Jupiter.

More than 600 Amurs are currently known. They rotate in orbits with a semi-major axis of more than 1.0 AU. and distances at perihelion from 1.017 to 1.3 a. e. The diameter of the largest cupid - Ganymede - is 32 km.

Apollo asteroids include asteroids that cross the Earth's orbit and have a semi-major axis of at least 1 AU. Apollos, along with Atons, are the smallest asteroids. Their largest representative is Sisyphus with a diameter of 8.2 km. In total, more than 3.5 thousand Apollos are known.

The above groups of asteroids form the so-called “main” belt, in which the deposits are concentrated.

Beyond the "main" asteroid belt is a class of small planets called Trojans or Trojan asteroids.

Trojan asteroids are located in the vicinity of the Lagrange points L4 and L5 in the 1:1 orbital resonance of any planets. Most of the Trojan asteroids were discovered near the planet Jupiter. There are Trojans near Neptune and Mars. They are believed to exist near the Earth.

The Trojans of Jupiter are divided into 2 large groups: at point L4 there are asteroids, called after Greek heroes, and moving ahead of the planet; at point L5 there are asteroids called after the defenders of Troy and moving behind Jupiter.

At Neptune's currently Only 7 Trojans are known, 6 of which are moving ahead of the planet.

Only 4 Trojans have been identified on Mars, 3 of which lie near the L4 point.

Trojans are large asteroids with a diameter often greater than 10 km. The largest of them is the Greek of Jupiter - Hector, with a diameter of 370 km.

Between the orbits of Jupiter and Neptune, there is a belt of Centaurs - asteroids that simultaneously exhibit the properties of both asteroids and comets. Thus, the first of the discovered Centaurs, Chiron, experienced a coma when approaching the Sun.

It is currently believed that there are more than 40 thousand centaurs in the solar system with a diameter of more than 1 km. The largest of them is Chariklo with a diameter of about 260 km.

The Damocloid group includes asteroids that have very elongated orbits and are located at aphelion further than Uranus, and at perihelion closer to Jupiter, and sometimes even Mars. It is believed that Damocloids are the cores of planets that have lost volatile substances, which was made on the basis of observations showing the presence of coma in a number of asteroids of this group and on the basis of a study of the parameters of the orbits of Damocloids, which revealed that they revolve around the Sun in the direction opposite to the movement major planets and other groups of asteroids.

Spectral classes of asteroids

Based on color, albedo, and spectral characteristics, asteroids are conventionally divided into several classes. Initially, according to the classification of Clark R. Chapman, David Morrison and Ben Zellner, there were only 3 spectral classes of asteroids. Then, as scientists studied, the number of classes expanded and today there are 14 of them.

Class A includes only 17 asteroids lying within the main belt and characterized by the presence of the mineral olivine. Class A asteroids are characterized by a moderately high albedo and a reddish color.

Class B includes carbon asteroids with a bluish spectrum and almost complete absence absorption at wavelengths below 0.5 µm. Asteroids of this class lie mainly within the main belt.

Class C is formed by carbon asteroids, whose composition is close to the composition of the protoplanetary cloud from which the Solar System was formed. This is the most numerous class, to which 75% of all asteroids belong. They circulate in the outer regions of the main belt.

Asteroids with a very low albedo (0.02-0.05) and a smooth reddish spectrum without clear absorption lines are classified as spectral class D. They lie in the outer regions of the main belt at a distance of at least 3 AU. from the sun.

Class E asteroids are most likely remnants of the outer shell of a larger asteroid and are characterized by a very high albedo (0.3 or higher). In their composition, asteroids of this class are similar to meteorites known as enstatite achondrites.

Class F asteroids belong to the group of carbon asteroids and differ from similar objects of class B in the absence of traces of water, which absorbs at a wavelength of about 3 microns

Class G includes carbon asteroids with strong ultraviolet absorption at a wavelength of 0.5 microns.

Class M includes metallic asteroids with a moderately high albedo (0.1-0.2). On the surface of some of them there are outcrops of metals (nickel iron), like some meteorites. Less than 8% of all known asteroids belong to this class.

Asteroids with a low albedo (0.02-0.07) and a smooth reddish spectrum without specific absorption lines belong to class P. They contain carbons and silicates. Such objects predominate in the outer regions of the main belt.

Class Q includes a few asteroids from the inner regions of the main belt, whose spectrum is similar to chondrites.

Class R includes objects with high concentrations of olivine and pyroxene in the outer regions, possibly with the addition of plagioclase. There are few asteroids of this class and they all lie in the inner regions of the main belt.

17% of all asteroids belong to class S. Asteroids of this class have a silicon or stony composition and are located mainly in areas of the main asteroid belt at a distance of up to 3 AU.

Scientists classify T asteroids as objects with a very low albedo, dark surface and moderate absorption at a wavelength of 0.85 microns. Their composition is unknown.

The last class of asteroids identified to date - V, includes objects whose orbits are close to the orbital parameters of the largest representative of the class - asteroid (4) Vesta. In their composition they are close to S class asteroids, i.e. consist of silicates, stones and iron. Their main difference from S-class asteroids is their high pyroxene content.

Origin of asteroids

There are two hypotheses for the formation of asteroids. According to the first hypothesis, the existence of the planet Phaeton in the past is assumed. It did not exist for long and was destroyed during a collision with a large celestial body or due to processes within the planet. However, the formation of asteroids is most likely due to the destruction of several large objects remaining after the formation of the planets. Education of a large celestial body- planets - could not happen within the main belt due to the gravitational influence of Jupiter.

Asteroid satellites

In 1993, the Galileo spacecraft received an image of the asteroid Ida with a small satellite, Dactyl. Subsequently, satellites were discovered on many asteroids, and in 2001 the first satellite was discovered on a Kuiper belt object.

To the bewilderment of astronomers, joint observations carried out using ground-based instruments and the Hubble telescope showed that in many cases these satellites are quite comparable in size to the central object.

Dr. Stern conducted research to find out how such dual systems. Standard model formation large satellites suggests that they are formed as a result of a collision between a parent object and a large object. Such a model makes it possible to satisfactorily explain the formation of double asteroids, systems Pluto-Charon, and can also be directly applied to explaining the process of formation of the Earth-Moon system.

Stern's research cast doubt on a number of provisions of this theory. In particular, the formation of objects requires collisions with energy, which are very unlikely given possible quantity and the masses of Kuiper Belt objects both in their original and modern states.

This leads to two possible explanations: either the formation of binary objects did not occur as a result of collisions, or the surface reflectance of Kuiper objects (which is used to determine their size) is significantly underestimated.

According to Stern, NASA's new space infrared telescope SIRTF (Space Infrared Telescope Facility), which was launched in 2003, will help resolve the dilemma.

Asteroids. Collisions with the Earth and other cosmic bodies

From time to time, asteroids can collide with cosmic bodies: planets, the Sun, and other asteroids. They also collide with the Earth.

To date, more than 170 large craters are known on the surface of the Earth - astroblemes (“star wounds”), which are places where celestial bodies fell. The largest crater for which high probability extraterrestrial origin has been established - Vredefort in South Africa, with a diameter of up to 300 km. The crater was formed as a result of the fall of an asteroid with a diameter of about 10 km more than 2 billion years ago.

The second largest is impact crater Sudbury in the Canadian province of Ontario, formed by the fall of a comet 1850 million years ago. Its diameter is 250 km.

There are 3 more drums known on Earth meteorite crater with a diameter of more than 100 km: Chicxulub in Mexico, Manicouagan in Canada and Popigai (Popigai Basin) in Russia. The Chicxulub crater is associated with the fall of an asteroid, which 65 million years ago caused the Cretaceous-Paleogene extinction.

Currently, scientists believe that celestial bodies equal in size to the Chicxulub asteroid fall to Earth approximately once every 100 million years. Smaller bodies fall to Earth much more often. So, 50 thousand years ago, i.e. already at the time when people lived on Earth modern type, in the state of Arizona (USA) a small asteroid with a diameter of about 50 meters fell. The impact created the Barringer crater, 1.2 km across and 175 m deep. In 1908, in the area of ​​the Podkamennaya Tunguska River at an altitude of 7 km. A fireball with a diameter of several tens of meters exploded. There is still no consensus on the nature of the fireball: some scientists believe that a small asteroid exploded over the taiga, while others believe that the cause of the explosion was the nucleus of a comet.

On August 10, 1972, eyewitnesses observed a huge fireball over Canadian territory. Apparently we are talking about an asteroid with a diameter of 25 m.

On March 23, 1989, asteroid 1989 FC with a diameter of about 800 meters flew by at a distance of 700 thousand km from Earth. The most interesting thing is that the asteroid was discovered only after it moved away from the Earth.

October 1, 1990 over Pacific Ocean A fireball with a diameter of 20 meters exploded. The explosion was accompanied by a very bright flash, which was recorded by two geostationary satellites.

On the night of December 8-9, 1992, many astronomers observed the passage of asteroid 4179 Toutatis with a diameter of about 3 km past the Earth. An asteroid passes by the Earth every 4 years, so you also have the opportunity to explore it.

In 1996, a half-kilometer asteroid passed at a distance of 200 thousand km from our planet.

As you can see from this, it is far from full list, asteroids are quite frequent guests on Earth. According to some estimates, asteroids with a diameter of more than 10 meters invade the Earth's atmosphere every year.

Asteroids are celestial bodies that were formed due to the mutual attraction of dense gas and dust orbiting our Sun at early stage its formation. Some of these objects, like an asteroid, have reached enough mass to form a molten core. At the moment Jupiter reached its mass, most of the planetesimals (future protoplanets) were split and ejected from the original asteroid belt between Mars and. During this era, some asteroids were formed due to the collision of massive bodies within the influence gravitational field Jupiter.

Classification by orbits

Asteroids are classified based on features such as visible reflections of sunlight and orbital characteristics.

According to the characteristics of their orbits, asteroids are grouped into groups, among which families can be distinguished. A group of asteroids is considered to be a number of such bodies whose orbital characteristics are similar, that is: semi-axis, eccentricity and orbital inclination. An asteroid family should be considered a group of asteroids that not only move in close orbits, but are probably fragments of one big body, and formed as a result of its split.

The largest of famous families may number several hundred asteroids, the most compact ones being within ten. Approximately 34% of asteroid bodies are members of asteroid families.

As a result of the formation of most groups of asteroids in the Solar System, their parent body was destroyed, but there are also groups whose parent body survived (for example).

Classification by spectrum

Spectral classification is based on spectrum electromagnetic radiation, which is the result of the asteroid reflecting sunlight. Registration and processing of this spectrum makes it possible to study the composition of the celestial body and identify the asteroid in one of the following classes:

• A group of carbon asteroids or C-group. Representatives of this group consist mostly of carbon, as well as elements that were part of the protoplanetary disk of our Solar System in the early stages of its formation. Hydrogen and helium, as well as other volatile elements, are virtually absent from carbon asteroids, but various minerals may be present. Another distinctive feature such bodies have a low albedo - reflectivity, which requires the use of more powerful tools observations than in the study of asteroids of other groups. More than 75% of asteroids in the Solar System are representatives of the C-group. The most famous bodies of this group are Hygeia, Pallas, and once - Ceres.
• A group of silicon asteroids or S-group. These types of asteroids are composed primarily of iron, magnesium and some other rocky minerals. For this reason, silicon asteroids are also called rocky asteroids. Such bodies have a fairly high albedo, which makes it possible to observe some of them (for example, Iris) simply with the help of binoculars. The number of silicon asteroids in the Solar System is 17% of the total, and they are most common at a distance of up to 3 astronomical units from the sun. The largest representatives of the S-group: Juno, Amphitrite and Herculina.

> Asteroids

All about asteroids for children: description and explanation with photos, Interesting Facts, what is an asteroid and meteorites, the asteroid belt, falling to Earth, types and name.

For the little ones It is important to remember that an asteroid is a small rocky object, devoid of air, orbiting a star and not large enough to qualify as a planet. Parents or teachers At school can explain to the children, What total weight asteroids are inferior to terrestrial ones. But don't think that their size doesn't pose a threat. In the past, many of them crashed into our planet, and this may happen again. That is why researchers are constantly studying these objects, calculating their composition and trajectory. And if a dangerous one rushes towards us space rock, then it’s better to be prepared.

Asteroid Formation - Explained for Kids

Begin explanation for children It can be explained by the fact that asteroids are residual material from the formation of our system 4.6 billion years ago. When it was formed, it simply did not allow other planets to appear in the interval between itself and. Because of this, small objects there collided and turned into asteroids.

It is important that children understood this process, because scientists are diving deeper into the past every day. IN Lately There were two theories: the Nice model and the Grand Tack. They believe that before settling on familiar orbits, gas giants traveled through the system. This movement could tear asteroids out of the main belt, changing its original appearance.

Physical characteristics of asteroids - explanation for children

Asteroids vary in size. Some can reach the volume of Ceres (940 km in width). If we take the smallest one, it was 2015 TC25 (2 meters), which flew near us in October 2015. But children may not worry, since asteroids have little chance of heading towards us in the near future.

Almost all asteroids formed in irregular shape. Although the largest ones may approach the sphere. There are noticeable depressions and craters on them. For example, Vesta has a huge crater (460 km). The surface of most is covered with dust.

Asteroids also go around the star in an ellipse, so they make chaotic somersaults and rotations on their way. For the little ones It will be interesting to hear that some have a small satellite or two moons. There are binary or double asteroids, as well as triple ones. They are approximately the same size. Asteroids can evolve if a planet grabs them with its gravity. Then they increase their mass, go into orbit and turn into satellites. Among the candidates: and (Martian moons), as well as most of the moons of Jupiter, and.

They differ not only in size, but also in shape. They can be solid pieces or small fragments bound together by gravity. Between Uranus and Neptune there is an asteroid with own system rings And another one is endowed with six tails!

The average temperature reaches -73°C. They have existed virtually unchanged for billions of years, so it is important to study them to get a glimpse of the primitive world.

Classification of asteroids - explanation for children

The objects are located in three zones of our system. Most of grouped in a giant ring-shaped region between the orbits of Mars and Jupiter. This is the main belt, containing more than 200 asteroids with a diameter of 100 km, as well as from 1.1-1.9 million with a diameter of 1 km.

Parents or At school must explain to the children that not only asteroids of the solar system live in the belt. Ceres was previously thought to be an asteroid until it was brought into the classroom dwarf planets. Moreover, not so long ago scientists discovered new class- “main belt asteroids”. These are small stone objects with tails. The tail appears when they crash, break up, or there is a hidden comet in front of you.

A lot of stones are located beyond the main belt. They gather near the major planets in certain places(Lagrange point) where solar and planetary gravity are in balance. The largest number of representatives are the Trojans of Jupiter (in numbers they almost reach the size of the asteroid belt). Neptune, Mars and Earth also have them.

Near-Earth asteroids orbit closer to us than . Cupids come close in orbit, but do not intersect with the earth's. The Apollos intersect with our orbit, but most of the time they are located in the distance. Atons also cross the orbit, but are inside it. The atyrs are the closest. According to the European Space Agency, we are surrounded by 10,000 known near-Earth objects.

In addition to being divided by orbit, they also come in three composition classes. C-type (carbonaceous) is gray and occupies 75% of known asteroids. Most likely formed from clay and rocky silicate rocks and inhabit external zones main belt. S-type (silica) – green and red, represent 17% of objects. Made from silicate materials and nickel-iron and predominant in the inner belt. M-type (metallic) – red and make up the rest of the representatives. Consist of nickel-iron. Certainly, children should know that there are many more varieties based on composition (V-type - Vesta, which has a basaltic volcanic crust).

Asteroid attack - explanation for children

4.5 billion years have passed since the formation of our planet and the fall of asteroids to Earth was a common occurrence. To cause serious damage to Earth, an asteroid would have to be ¼ mile wide. Because of this, such an amount of dust will rise into the atmosphere that it will create the conditions “ nuclear winter" On average, strong impacts occur once every 1000 years.

Smaller objects fall at intervals of 1000-10000 years and can destroy the whole city or create a tsunami. If the asteroid has not reached 25 meters, it will most likely burn up in the atmosphere.

IN outer space Dozens of potential dangerous strikers travel and are constantly monitored. Some come pretty close, while others are considering the possibility in the future. To have time to react, there must be a reserve of 30-40 years. Although now there is more and more talk about technology to combat such objects. But there is a danger of missing the threat and then there simply will be no time left to react.

Important explain for the little ones that a possible threat also contains benefits. After all, once upon a time it was an asteroid impact that caused our appearance. When formed, the planet was dry and barren. Falling comets and asteroids left water and other carbon-based molecules on it, allowing life to form. During the formation of the solar system, objects stabilized and allowed to gain a foothold modern forms life.

If an asteroid or part of it falls on a planet, it is called a meteorite.

Composition of asteroids - explanation for children

• Iron meteorites: iron (91%), nickel (8.5% ), cobalt (0.6%).
• Stony meteorites: oxygen (6%), iron (26%), silicon (18%), magnesium (14%), aluminum (1.5%), nickel (1.4%), calcium (1.3%) .

Discovery and name of asteroids - explanation for children

In 1801, a priest from Italy, Giuseppe Piazzi, was creating star map. Quite by accident, between Mars and Jupiter, he noticed the first and large asteroid Ceres. Although today it is already a dwarf planet, because its mass accounts for ¼ of the mass of all known asteroids in the main belt or nearby.

In the first half of the 19th century, a lot of such objects were found, but all were classified as planets. It was not until 1802 that William Herschel proposed the word "asteroid", although others continued to refer to them as "minor planets". By 1851, 15 new asteroids had been found, so the naming principle had to be changed, adding numbers. For example, Ceres became (1) Ceres.

The International Astronomical Union is not strict in naming asteroids, so you can now find objects named after Spock from Star Trek or rock musician Frank Happa. 7 asteroids were named after the Columbia crew who died in 2003.

The numbers are also added to them - 99942 Apophis.

Asteroid Research - Explained for Kids

First close-up The asteroids were removed by the Galileo spacecraft in 1991. In 1994, he also managed to find a satellite orbiting an asteroid. For a long time NASA studied the near-Earth object Eros. After much deliberation, they decided to send the device to him. NEAR made a successful landing, becoming the first in this regard.

Hayabusa became the first vehicle to land and take off from an asteroid. He went in 2006 and returned in June 2010, bringing samples with him. NASA launched the Dawn mission in 2007 to study Vesta in 2011. A year later, they traveled from the asteroid to Ceres and reached it in 2015. In September 2016, NASA sent OSIRIS-REx to explore the asteroid Bennu.

A small body in the solar system that moves in orbit around the sun is called an asteroid. Asteroids are significantly fewer planets in size and do not have their own atmosphere, despite the fact that, like planets, they can have their own satellites. Asteroids are made of rocks and metals, mainly nickel and iron.


Term "asteroid" translated from Greek language means « star-like» . This name was coined by William Herschel, who noticed that through a telescope lens asteroids look like small points of stars. Planets are visible through a telescope as disks.

Until 2006, a synonym for the term “asteroid” was “minor planet”. Asteroids differ from meteoroids in size: the diameter of an asteroid must be at least thirty meters.

Sizes and motion of asteroids

The largest asteroids known today are (4) Vesta and (2) Pallas, with a diameter of about 500 kilometers. Vesta can be seen from Earth with the naked eye. The third large asteroid, Ceres, was reclassified as a dwarf planet in 2006. The dimensions of Ceres are about 909 by 975 kilometers.

According to scientists, there are between a million and two million asteroids larger than a kilometer in diameter in the solar system.


Most of these celestial bodies are located in the belt between Jupiter and Mars, but individual asteroids can move in an elliptical orbit outside this belt, around the Sun. There is another well-known asteroid belt, not far from the orbits of Pluto and Neptune - the Coyer Belt.

Asteroids, as already mentioned, do not stand still; in the process of movement they can collide with each other and satellites. On the surface of planets and satellites that asteroids collided with, deep marks - craters - remain. The diameter of the crater can reach several kilometers. During a collision, relatively small fragments - meteorites - can break off from asteroids.

Origin and features

Scientists have been trying for a very long time to find an answer to the question - where do asteroids come from? Today, two versions are popular. According to one of them, asteroids are the remnants of matter from which, in fact, all the planets of the solar system were formed. Another theory suggests that asteroids are fragments of large planets that previously existed and were destroyed due to an explosion or collision.


Asteroids are cold cosmic bodies. This is, in essence, huge stones, Not radiating heat and not reflecting it from the Sun, since they are very far from it. Even an asteroid located close to the star, having heated up, will give off this heat almost immediately.

What are the names of asteroids?

The first discovered asteroids were named after ancient Greek mythological heroes and gods. By a strange coincidence, at first it was female names, but only an asteroid with an unusual orbit could count on a male name. Later, this trend gradually faded away.

In addition, the right to give asteroids any names was given to people who discovered them for the first time. Thus, today, whoever discovers a new asteroid can give it a name according to his taste, and even call it his own own name.

But there is also certain rules naming asteroids. They can be given names only after the orbit of the celestial body has been reliably calculated, and until that time the asteroid is given unstable name. The asteroid's designation reflects the date it was discovered.

For example, 1975DC, where the numbers represent the year, the letter D is the number of the crescent in the year when the asteroid was discovered, and C is serial number celestial body in this crescent (the asteroid given as an example was the third to be discovered). There are 24 crescents in total, letters in english alphabet 26, so they decided not to use two letters - I and Z - when naming asteroids.


If more than 24 asteroids are discovered in one crescent, the second letter is assigned an index of 2, the venture - 3, and so on. And after the asteroid receives an official name (and it happens that this takes more than one decade - all this time the orbit is being calculated), its name includes the serial number and the name itself.