Potentially dangerous asteroids. How dangerous is the threat from space, what to do with the found meteorite

12.10.2019

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The Chelyabinsk fireball drew attention to space, from where asteroids and meteors can be expected to fall. Interest in meteorites, their search and sale has increased.

Chelyabinsk meteorite, photo from Polit.ru website

Asteroid, meteor and meteorite

flight paths asteroids designed for a century ahead, they are constantly monitored. These cosmic bodies potentially dangerous for the Earth (the size of a kilometer or more) shine with light reflected from the Sun, so they appear dark from the Earth part of the time. Amateur astronomers are not always able to see them, as city lighting, haze, etc. interfere. Interestingly, most of the asteroids are discovered not by professional astronomers, but by amateurs. Some are even awarded international prizes for this. There are such lovers of astronomy in Russia and other countries. Russia, unfortunately, is losing because of the lack of telescopes. Now that the decision to fund the work to protect the Earth from a space threat has been made public, scientists have hope to acquire telescopes that can scan the sky at night and warn of imminent danger. Astronomers also hope to receive modern wide-angle telescopes (at least two meters in diameter) with digital cameras.

smaller asteroids, meteoroids, flying in near-Earth space outside the atmosphere, can be seen more often when they fly close to the Earth. And the speed of these celestial bodies is about - 30 - 40 km per second! The flight of such a "pebble" to the Earth can be predicted (at best) only one or two days in advance. In order to understand how small this is, the following fact is indicative: the distance from the Moon to the Earth is overcome in just a few hours.

Meteor looks like a shooting star. It flies in the Earth's atmosphere, often adorned with a burning tail. Real things happen in heaven meteor showers. They are more properly called meteor showers. Many are already known. However, some happen unexpectedly when the Earth encounters rocks or pieces of metal roaming the solar system.

fireball, a very large meteor, appears to be a fireball with sparks flying in all directions and a bright tail. The fireball is visible even against the background of the daytime sky. At night, it can illuminate vast areas. The path of the fireball is marked with a smoky stripe. It has a zigzag shape due to air currents.

When a body passes through the atmosphere, a shock wave is generated. A strong shock wave is capable of shaking buildings and the ground. It generates blows similar to explosions and roar.

A space body that has fallen to Earth is called meteorite. This is the rock-hard remnant of those meteoroids lying on the ground that were not completely destroyed during their movement in the atmosphere. In flight, air resistance starts braking, and kinetic energy turns into heat and light. Surface layer temperature and air shell while reaching several thousand degrees. The meteor body partially evaporates and throws out fiery drops. The fragments of the meteor during the landing quickly cool down and fall to the ground warm. From above they are covered with a bark of melting. The place of fall often takes the form of a depression. L. Rykhlova, head of the department of space astrometry at the Institute of Astronomy of the Russian Academy of Sciences, reported that “about 100 thousand tons of meteoroid matter falls on the Earth every year” (“Echo of Moscow”, 17.02.2013). There are very small and fairly large meteorites. So, the Goba meteorite (1920, South West Africa, iron) had a mass of about 60 tons, and the Sikhote-Alinsky (1947, the USSR, which fell with iron rain) - an estimated mass of about 70 tons, collected 23 tons.

Meteorites are made up of eight basic elements: iron, nickel, magnesium, silicon, sulfur, aluminum, calcium, and oxygen. There are other elements, but in small quantities. Meteorites vary in composition. The main ones are: iron (iron in combination with nickel and a small amount of cobalt), stony (combination of silicon with oxygen, metal inclusions are possible; small rounded particles are visible at the break), iron-stone (an equal amount of stony and iron with nickel). Some meteorites are of Martian or lunar origin: when large asteroids fall on the surface of these planets, an explosion occurs, and parts of the surface of the planets are ejected into space.

Sometimes meteorites are confused with tektites. These are small black or greenish-yellow molten pieces of silicate glass. They are formed at the moment of the impact of large meteorites on the Earth. There is an assumption about the extraterrestrial origin of tektites. Outwardly, tektites resemble obsidian. They are collected, and jewelers process and use these " gems» to decorate their products.

Are meteorites dangerous to humans?

Only a few cases have been recorded direct hit meteorites in houses, cars or in people. Most of the meteorites end up in the ocean (almost three-quarters of the earth's surface). Densely populated and industrial areas occupy a smaller area. The chance of hitting them is much less. Although sometimes, as we see, this happens and leads to great destruction.

Can you touch meteorites with your hands? They are not considered to pose any danger. But take meteorites dirty hands not worth it. They are advised to immediately put in a clean plastic bag.

How much does a meteorite cost?

Meteorites can be distinguished by a number of features. First of all, they are very heavy. On the surface of the “stone”, smoothed dents and depressions (“fingerprints on clay”) are clearly visible, there is no layering. Fresh meteorites are usually dark, as they melt as they fly through the atmosphere. This characteristic dark melting crust is about 1 mm thick (more common). A meteorite is often recognized by its blunt head. Fracture is often gray color, with small balls (chondrules) that differ from the crystal structure of granite. Iron inclusions are clearly visible. From oxidation in air, the color of meteorites that have lain on the ground for a long time becomes brown or rusty. Meteorites are highly magnetized, causing the compass needle to deviate.

No matter how skeptical people are about the Hollywood story about the fall of a giant asteroid to Earth, space can still pose a serious danger to our planet. Most real threat, by and large, comes precisely from the depths of the vast universe.

Scientists have found that in the history of the planet there have been numerous collisions with asteroids, and with rather serious consequences. This explains the attention of scientists to dangerous asteroids. These asteroids include those whose hypothetical collision with our planet could lead to the death of mankind. Thus, NASA scientists have identified over 150 celestial bodies that pose a potential threat to human civilization.

The topic of “asteroid attacks” has recently become a topic of interest for scientists. Thus, the fall of meteorites until the second half of the 18th century was taken as an optical illusion. Experts back in the 1960s tried to explain the appearance of craters by "terrestrial" reasons. Now their cosmic origin is beyond doubt.

So, the death of dinosaurs is recorded on the "conscience" of the asteroid, the diameter of which was about 15 kilometers. 65 million years ago, a collision with this asteroid, along with dinosaurs, sent about 85% of plant and animal species to the next world. As a result of the fall of this giant asteroid, a crater was formed, the diameter of which was 200 kilometers. Billions of tons of water vapor and dust, as well as ash and soot from the monstrous fire, rose into the atmosphere. All this eclipsed the sunlight for many months. This could lead to a catastrophic drop in temperature on Earth.

There are many predictions and facts that point to the end of the world in 2012. But how exactly this will happen, no one knows. The Earth is just a crumb in the Universe, which appeared as a result of the interaction of cosmic bodies, and it is possible that it will also disappear. The fall of the asteroid, most likely, will not destroy the planet itself, but will rid it of people, animals and plants, i.e. from life. Will the Earth shatter into many pieces? Or maybe turn into Mars? So far, one can only speculate on this subject, based on the data that NASA shares with the general public.

Asteroids and comets often fly in quite dangerous proximity to the Earth, and even the slightest violation of their trajectory can lead to unpredictable consequences. So, if a comet hits the glaciers, it will cause them to melt, global warming as well as floods. Some scientists claim that in the entire history of the planet Earth, it collided with an asteroid about 6 times. Craters testify to this, the origin of which can only be explained by the fall of an asteroid to Earth.

The consequences of the fall of an asteroid can be very different. It all depends on the size of the asteroid, the place where it will fall, and on the speed of its movement. So, for example, an asteroid with a diameter of about 500 km will lead to the death of all life on Earth, and within a day. Impact force will cause a firestorm that will sweep away all life in its path. In less than a day, a wave of death will circle the planet and destroy all life on it. It is likely that the simplest organisms will survive and start anew the process of evolution on Earth.

An asteroid with a smaller diameter, when falling into the ocean, can cause a giant tsunami up to 100 meters high. Such a wave can wash away kilometers of the coastal zone from the face of the planet. Such a tsunami, among other things, can cause a number of man-made disasters. If the asteroid falls on any continent, then it will immediately destroy a giant part of the land. All life on the planet will perish as a result.

Should we expect such an end of the world? Amy Mainzer, one of the Laboratory workers jet propulsion NASA claims that near the Earth at this moment hundreds of asteroids rotate, capable of destroying all life on the planet. The chances of a planet colliding with an asteroid, according to calculations, are now small. However, one cannot be completely sure of this, since the cosmos is completely unpredictable. Perhaps a dangerous asteroid is flying towards the Earth at this very moment. Technologies are now developing quite rapidly, however, despite this, there is still no system that could give accurate information regarding the movement of all space bodies. But to imagine the full power of the potential danger, it is enough to look at the location of the asteroid belt relative to our planet.

Mars is closest to the belt. At the moment, there is a lot of evidence that there was once life on this planet, but for unknown reasons, it died. The most likely version of death is the fall of an asteroid. The powerful wave formed during the impact destroyed all life. The next victim may well be the Earth, as it is quite close to the asteroid belt.

Scientists such as Morrison and Chapman argue that once every 500 thousand years a global catastrophe occurs on the planet due to the fall of asteroids. According to statistics, asteroids as small as 10 kilometers fall every 100 million years. They leave almost no chance for humanity and the animal world to survive. Scientists believe that if such a collision occurs in our time, all of humanity will perish. According to experts, the biggest threat comes from medium-sized celestial bodies. According to experts, over 500 thousand years, more than a billion people died as a result of the falls of such bodies. The earth was constantly bombarded by space.

Currently, according to scientists, the most dangerous for our planet are such asteroids as the asteroid YU 55, Eros, Vesta and Apophis. The fact that there is a real threat from outer space was only discussed when the asteroid Apophis was discovered. Its diameter is approximately 270 meters, and its weight is about 27 million tons. The collision of this asteroid with the Earth, according to the latest data, is possible in 2036. Even if it does not fall to Earth, it can cause significant damage to space technology. It will approach the Earth at a distance of 30-35 thousand kilometers, and it is at this altitude that it works most of spacecraft. Apophis in this moment considered the first among potentially dangerous celestial bodies. In 2013, it will fly relatively close to our planet and scientists will be able to see the true nature of the threat and determine whether it is possible to somehow prevent a catastrophe.

Russian scientists did not wait for 2013 and created a group to decide what to do if it turns out that the collision of Apophis with the Earth does happen. The approach of an asteroid in 2029 to the Earth will change its orbit, for this reason, forecasts about the subsequent direction of movement are very uncertain without more data. After an asteroid hits the Earth's surface, according to preliminary estimates, powerful explosion at 200 megatons.

Also, the asteroid 2005 YU 55 is constantly approaching the Earth with a certain frequency. In November 2011, it flew past our planet at a dangerous close range. And since then, it has been considered one of the most dangerous asteroids. The largest asteroid in the belt is Vesta, which is visible to the naked eye from Earth. This is explained by its ability to approach the planet at a distance of only 170 million kilometers. And there are a lot of such potentially dangerous asteroids.

But, despite this, astronomers currently do not see any serious danger for the Earth from asteroids. But, as mentioned earlier, space is unpredictable, so potentially dangerous objects are constantly monitored. For these purposes, especially powerful space telescopes with especially sensitive optics are being developed. Without them, it is quite difficult to spot asteroids, as they reflect light rather than emit it.

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The threat to the Earth can be carried by objects approaching it at a distance of at least 8 million kilometers and large enough not to collapse when entering the planet's atmosphere. They are a danger to our planet.

1. Apophis

Until recently, the asteroid Apophis, discovered in 2004, was called the object with the highest probability of a collision with the Earth. Such a collision was considered possible in 2036. However, after Apophis passed by our planet in January 2013 at a distance of about 14 million km. NASA experts have reduced the likelihood of a collision to a minimum. The chances, according to Don Yeomans, head of the near-Earth object laboratory, are less than one in a million.

Nevertheless, experts have calculated the approximate consequences of the fall of Apophis, whose diameter is about 300 meters and weighs about 27 million tons. Thus, the energy released during the collision of the body with the Earth's surface will be 1717 megatons. The strength of an earthquake within a radius of 10 kilometers from the place of impact can reach 6.5 on the Richter scale, and the wind speed will be at least 790 m/s. In this case, even fortified objects will be destroyed.

Asteroid 2007 TU24 was discovered on October 11, 2007, and already on January 29, 2008, it flew near our planet at a distance of about 550 thousand km. Due to its extraordinary brightness - the 12th magnitude - it could be seen even in medium-power telescopes. Such a close passage of a large celestial body from the Earth is a rare occurrence. The next time an asteroid of the same size will approach our planet will be in 2027.

TU24 is a massive celestial body comparable to the size of the University building on Sparrow Hills. According to astronomers, the asteroid is potentially dangerous because it crosses the Earth's orbit approximately once every three years. But, at least until 2170, according to experts, it does not threaten the Earth.

The space object 2012 DA14 or Duende belongs to the near-Earth asteroids. Its dimensions are relatively modest - a diameter of about 30 meters, a weight of about 40,000 tons. According to scientists, it looks like a giant potato. Immediately after the discovery on February 23, 2012, it was found that science was dealing with an unusual celestial body. The fact is that the orbit of the asteroid is in 1:1 resonance with the Earth. This means that the period of its revolution around the Sun approximately corresponds to the Earth's year.

For a long time, Duende may be near the Earth, but astronomers are not yet ready to predict the behavior of a celestial body in the future. Although, according to current calculations, the probability of Duende colliding with the Earth before February 16, 2020 will not exceed one chance in 14,000.

Immediately after the discovery on December 28, 2005, the asteroid YU55 was classified as potentially dangerous. In diameter, the space object reaches 400 meters. It has an elliptical orbit, which indicates the instability of its trajectory and unpredictable behavior. In November 2011, the asteroid has already aroused scientific world, flying up to a dangerous distance to the Earth of 325 thousand kilometers - that is, it turned out to be closer than the Moon. Interestingly, the object is completely black and almost invisible in the night sky, for which astronomers nicknamed it "Invisible". Scientists then seriously feared that a space alien would enter earth's atmosphere.

An asteroid with such an intriguing name is an old acquaintance of earthlings. It was discovered by the German astronomer Karl Witt back in 1898 and was the first near-Earth asteroid discovered. Eros also became the first asteroid to acquire an artificial satellite. It's about about the NEAR Shoemaker spacecraft, which landed on a celestial body in 2001.

Eros is the largest asteroid in the inner solar system. Its dimensions are amazing -33 x 13 x 13 km. average speed giant 24.36 km/s. The shape of the asteroid is similar to a peanut, which affects the uneven distribution of gravity on it. The impact potential of Eros in the event of a collision with the Earth is simply enormous. According to scientists, the consequences after an asteroid hit our planet will be more catastrophic than after the fall of Chicxulub, which allegedly caused the extinction of dinosaurs. The only consolation is that the chances of this happening in the foreseeable future are scanty.

Asteroid 2001 WN5 was discovered on November 20, 2001 and later fell into the category of potentially hazardous objects. First of all, one should be afraid that neither the asteroid itself nor its trajectory have been sufficiently studied. According to preliminary data, it can reach 1.5 kilometers in diameter. On June 26, 2028, the next approach of the asteroid to the Earth will take place, and the cosmic body will approach the minimum distance for itself - 250 thousand km. According to scientists, it can be seen through binoculars. This distance is enough to cause satellites to malfunction.

This asteroid was discovered by Russian astronomer Gennady Borisov on September 16, 2013 using a homemade 20 cm telescope. The object was immediately named almost by the dangerous threat among celestial bodies for the Earth. The diameter of the object is about 400 meters.
The approach of the asteroid to our planet is expected on August 26, 2032.

According to some assumptions, the block will sweep only 4 thousand kilometers from the Earth at a speed of 15 km / s. Scientists have calculated that in the event of a collision with the Earth, the energy of the explosion will be 2.5 thousand megatons of TNT. For example, the power of the largest thermonuclear bomb detonated in the USSR is 50 megatons.
To date, the probability of an asteroid colliding with the Earth is estimated at about 1/63,000. However, with further refinement of the orbit, the indicator can either increase or decrease.

What are asteroids and comets? Where do they live? What danger do they pose? How likely is a meteorite to hit Earth in the near future?

I want to say right away that I did not set the goal of this article to scare the reader with scary stories about a cosmic threat with a colorful description of a comet falling to Earth and the death of all life. I think it is unlikely that anyone will be able to do it better than in the movie "Armageddon" in the near future. Here I simply collected and systematized in a popular form the basic information about the small bodies of the solar system and tried to objectively answer the question: “Is it possible to sleep peacefully at night or should we be afraid that at any moment a rock the size of a house or a whole city and destroy, if not half the planet, then some small country?

The world of asteroids and comets.

I have two news for you - good and bad. I'll start with the bad: around the Sun within a sphere with a radius of 1 light year (this is a sphere in which the Sun can hold small bodies with its gravity) constantly circle trillions(!!!) blocks ranging in size from tens of meters to hundreds and even thousands of kilometers!

The good news is that the solar system has been in existence for 4.5 billion years and the initial mess of cosmic matter has long been structured into a stable system of planets, asteroids, comets, etc., which we observe. The period of massive meteorite bombardments, which the Earth and other planets experienced, remained in the distant prehistoric past. Almost everything large that was supposed to fall to Earth from space, fortunately, has already fallen. Right now the situation in the solar system is generally calm. Occasionally, a comet will please with its appearance - a guest from the very outskirts of the possessions of our luminary.

All large asteroids have been discovered, rewritten, registered, their orbits have been calculated, they do not pose a danger.

It is more difficult with small ones - there are more of them in space than there are ants in all anthills. It is simply impossible to register every space rock. Due to their small size, they are found only in the immediate vicinity of the Earth. And very small ones are not detected at all before entering the atmosphere. But such ones do not bring much harm, at most - they can scare with a loud bang before almost completely burning out. Although the glass in houses can also be broken, as the very Chelyabinsk meteorite did, which demonstrated the reality of the threat from space.

The greatest concern is caused by asteroids larger than 150 meters. Theoretically, their number is only "main belt" may be in the millions. Finding such a body at a sufficiently large distance to have time to do something is very difficult. And a meteorite measuring 150-300 meters is guaranteed to destroy the city if it hits it.

Thus, the threat from space is more than real. Meteorites have been falling to Earth throughout its history, and sooner or later it will happen again. To assess the level of danger, I propose to understand in more detail the structure of this heavenly economy.

Terminology.

Small bodies of the solar system- all natural objects revolving around the Sun, except for planets, dwarf planets and their satellites.

dwarf planets- bodies with a mass sufficient to maintain a shape close to spherical (from 300-400 km) due to their own gravity, but not dominating in their orbit.

— small bodies larger than 30 meters.
Small bodies less than 30 meters in size are called meteoroids.
Further, as the size decreases, go micrometeoroids(less than 1-2 mm), and then cosmic dust(particles smaller than 10 µm).
Meteorite- what is left of an asteroid or meteoroid after it fell to Earth.
fireball- a flash visible when a small body enters the atmosphere.
Comet- an icy small body. As it approaches the Sun, the ice and frozen gas evaporates, forming the tail and coma (head of the comet).
Aphelion is the farthest point of the orbit.
Perihelion is the closest point in the orbit to the Sun.
a.u.- Astronomical unit of distance, this is the distance from the Earth to the Sun (150 million km).

Place of mass concentration of small bodies. This is a wide band between the orbits of Mars and Jupiter, along which the main part of the asteroids of the central part of the solar system rotates:

Most of the small bodies of the solar system fly around the sun in groups in close orbits. This is due to the fact that over billions of years they experience gravitational effects from the planets (especially Jupiter) and gradually shift from unstable orbits, where such effects are maximum, to stable ones, where gravitational disturbances are minimal. Also, groups of asteroids arise during collisions, when a large asteroid falls apart into many small ones, or it remains intact, but many fragments break off from it. At the moment, dozens of groups (or families) of asteroids are known, but most of them belong to the main belt.

AT main belt 4 bodies larger than 400 km are known, about 200 bodies larger than 100 km, about 1000 larger than 15 km. Theoretically, it is estimated that there should be about 1-2 million asteroids larger than 1 km. Despite the huge number, the total mass of these stones is only 4% of the mass of the moon.

Previously, it was assumed that the main asteroid belt arose from the debris of the exploded planet Phaethon. But now a more likely version is that the planet in this area simply could not arise due to the proximity of the giant Jupiter.

The millions of asteroids in this belt, many of which could arrange Armageddon on Earth, do not pose a danger to us, since their orbits lie outside the orbit of Mars.

Collisions.

But sometimes they collide with each other, then some fragment can accidentally fall into the Earth. The probability of such an accident is extremely low. If you calculate it for a time period equal to the life of 2-3 generations, then these generations do not have to worry too much.

But the Earth has existed for billions of years, during which time everything has happened. For example, the extinction of about 80% of all life and 100% of dinosaurs 65 million years ago. It has been practically proven that this is to blame, the crater from which is located in the region of the Yucatan Peninsula (Mexico). Judging by the crater, it was a meteorite about 10 km in size. Presumably, it belonged to the Baptistina asteroid family, which was formed during the collision of a 170-km asteroid with another fairly large one.

How often do such collisions occur? I propose to turn on the spatial imagination and imagine the main asteroid belt reduced by 100 thousand times. On this scale, its width will become approximately equal to the width of the Atlantic Ocean. An asteroid with a diameter of 1 km will turn into a ball 1 cm in size. Four giant bodies - Ceres, Vesta, Pallas and Hygiea with sizes of 950, 530, 532 and 407 km, respectively, will become balls about 10, 5 and 4 meters in size. 100-meter asteroids (the minimum size that poses a sufficiently serious threat) will become 1 mm crumbs. Now let's mentally scatter them all over the Atlantic and imagine that they run smoothly in approximately one direction, for example, first from north to south, then back. Their trajectories are not exactly parallel - let some sail from London to the lower tip South America and others from New York to South Africa. Moreover, they complete their journey back and forth (orbital period) in 4-6 years (on such a scale, this approximately corresponds to a speed of 1 km / h).

Have you submitted this picture? On the same scale, the Earth in the closest position relative to any asteroid will be a 130-meter island in Indian Ocean. What is the probability that two asteroids collided and the fragment landed right in it!? Now, I think you will sleep more peacefully. At the very least, the anxiety about cosmic Armageddon, constantly fueled by the media, should fade into the background. Even if poured into Atlantic Ocean several million balls ranging in size from 1 millimeter to tens of centimeters and only a few hundred in size more than a meter then, with such a movement about which we spoke, intuition suggests that collisions and hits of fragments into the Earth in the near future can not be expected. And mathematical calculations give such data: asteroids with a size of 20 km or more hit each other once every 10 million years.

One of the typical pictures that are usually given as an illustration when describing the asteroid belt:

Now I think you understand that in real life it looks completely different. In fact, the ratio of distances between neighboring blocks and their sizes is much larger there than in this figure. It is measured in thousands of kilometers, sometimes hundreds, so interplanetary spacecraft have so far quietly flown through this belt without any complications.

However, despite all that has been said, it is from the Main Asteroid Belt that more than 99% of meteorite fragments found on Earth originate. They made a significant contribution to the "development" of life on Earth, periodically arranging mass extinctions of species on it. Well, that's why he is the Chief ..

Asteroids approaching the Earth.

As mentioned above, most asteroids belong to a family, that is, bodies of the same group fly in similar orbits. There are families of orbits which approach the Earth's orbit, or even cross it. The most dangerous of them are the families of Cupid, Apollo and Aton:

Amur group- the least threatening of these three, since it does not cross the Earth's orbit, but only approaches it. This is enough to pose a potential danger, since with such approaches, the Earth's gravity unpredictably changes the orbit of asteroids, and therefore the threat from a potential one can turn into a real one. Mars has the same effect on them, since they cross its orbit, therefore sometimes approaching it. About 4000 asteroids of this group are known, of course, most of them have not yet been discovered. The largest of them is Ganymede (not to be confused with the satellite of Jupiter), its diameter is 31.5 km. Another member of this group - Eros (34 X 11 km), is famous for the fact that for the first time in history a spacecraft landed on it - "NEAR Shoemaker" (NASA).

Apollo group. As can be seen in the diagram, the asteroids of this group, like the "cupids", at aphelion (the maximum distance from the Sun) go to the Main belt, and at perihelion they go inside the earth's orbit. That is, they cross it in two places. In this family, more than 5,000 members are known, mostly "trifle", the largest - 8.5 km.

Aten group. About 1,000 Atons are known (the largest is 3.5 km). They, on the contrary, ply inside the Earth's orbit, and only at aphelion go beyond its limits, also crossing our orbit.

In fact, the diagram shows the projections of the typical orbits of "Apollos" and "Atons". Each of the asteroids has a certain orbital inclination, so not every one of them crosses the Earth's orbit - most pass under or above it (or slightly to the side). But if it crosses, then there is a possibility that at some point the Earth will be at the same point with it - then a collision will occur.

This is how this space carousel turns from year to year. Astronomers around the world are watching every suspicious object, constantly discovering more and more. On the website of the "Center for Small Planets" I found a list of asteroids threatening the Earth (potentially dangerous). Asteroids in it are sorted starting from the most dangerous.

Apophis.

The orbit of the asteroid Apophis intersects the Earth's orbit in two places.

"Apophis" - one of the "atones", leads the list of the most dangerous asteroids, since the estimated distance at which it will pass the Earth is the smallest of all known - only 30-35 thousand km from the surface of our planet. Since there is a possibility of an error in the calculations due to inaccurate data, there is also a certain probability of a “hit”.

Its diameter is about 320 meters, the period of revolution around the Sun is 324 Earth days. That is, once every 162 days it practically flies through the Earth's orbit, but since the total length of the Earth's orbit is almost a billion kilometers, risky encounters are rare.

Apophis was discovered in July 2004 and approached Earth again in December. The July data was compared with the December data, the orbit was calculated and .. a big commotion began! Calculations have shown that in 2029 Apophis will fall to Earth with a probability of 3%! It was tantamount to a scientifically based prediction of the end of the world. Close observations of Apophis began, each new refinement of the orbit reduced the likelihood of Armageddon. The possibility of a collision in 2029 was practically refuted, but the rapprochement of 2036 fell under suspicion. In 2013, the next flyby of Apophis near the Earth (about 14 million km.) made it possible to refine its size and orbit parameters as much as possible, after which NASA scientists completely refuted the information about the threat of this asteroid falling to Earth.

A little about other small bodies of the solar system.

The most asteroid-dangerous part of our planetary system is left behind, we are moving towards its outskirts. As the distance increases, the potential danger of objects located there decreases accordingly. In other words, if, according to NASA, no one can be afraid of Apophis, then the danger of small bodies, which will be discussed below, completely tends to zero.

Trojans and Greeks.

Each major planet The solar system has points in orbit, once in which bodies with a small mass are in equilibrium between this planet and the Sun. These are the so-called Lagrange points, there are 5 of them in total. In two of them, which are 60 ° ahead and behind the planet, "Trojan" asteroids live.

Jupiter has the largest Trojan groups. Those who are ahead of him in orbit are called "Greeks", those who are behind are called "Trojans". About 2000 "Trojans" and 3000 "Greeks" are known. All of them are not located, of course, at one point, but are scattered along the orbit in areas with a length of tens of millions of kilometers.

In addition to Jupiter, Trojan groups have been discovered near Neptune, Uranus, Mars and the Earth. Venus and Mercury, most likely, also have them, but they have not yet been discovered, since the proximity of the Sun makes it difficult to conduct astronomical observations in these areas. By the way, at the Lagrange points of the Moon relative to the Earth, there are also at least clots of cosmic dust, and possibly small fragments of meteorites that have fallen into a gravitational trap.

Kuiper belt.

Further, as you move away from the Sun, beyond the orbit of Neptune (the most distant planet in the solar system), that is, at a distance of more than 30 AU. from the center, another vast asteroid belt begins - the Kuiper belt. It is approximately 20 times wider than the Main Belt and 100-200 times more massive. Conventionally, its outer boundary is taken to be 55 AU. from the sun. As you can see in the figure, the Kuiper belt is a huge torus (donut) lying beyond the orbit of Neptune: More than 1000 Kuiper Belt Objects (KBOs) are already known. Theoretical calculations say that there should be about 500,000 objects larger than 50 km, about 70,000 larger than 100 km, several thousand small planets (and maybe large ones) larger than 1000 km (so far only 7 of them have been discovered).

The most famous Kuiper belt object is Pluto. According to the new definition of the term "planet", it is no longer considered a full-fledged planet, but belongs to the dwarf ones, since it clearly does not dominate in its orbit.

Scattered disk.

The outer boundary of the Kuiper Belt smoothly merges into the Scattered Disk. Here, small bodies rotate in much more elongated and even more inclined orbits. At aphelion, scattered disk objects can move hundreds of AU away.

That is, the objects of this region do not adhere to any strict system in their rotation, but move along a variety of orbits. Therefore, in fact, the disk is called scattered. For example, objects with an orbital inclination of up to 78° have been discovered there. There is also an object that enters the orbit of Saturn and then moves away by 100 AU.

The largest known dwarf planet, Eris, rotates in the scattered disk, its diameter is about 2500 km, which is larger than that of Pluto. At perihelion, it enters the Kuiper belt, and at aphelion it recedes to a distance of 97 AU. from the sun. Its circulation period is 560 years.

The most extreme known object in this region is the dwarf planet Sedna (diameter 1000 km), at its maximum distance, it leaves us at a distance of 900 AU. It takes 11,500 years to revolve around the Sun.

It seems that all this is unattainable distant distances, but!. Two man-made objects are currently located in this area - the Voyager spacecraft, launched back in 1977. Voyager 1 went a little further than its partner, now it is at a distance of 19 billion kilometers from us (126 AU). Both devices are still successfully transmitting information about the level of cosmic radiation to Earth, while the radio signal reaches us in 17 hours. At this rate, the Voyagers will travel 1 light year (a quarter of the distance to the nearest star) in 40,000 years.

And we, mentally, of course, can overcome this distance in an instant. Move on..

Oort cloud.

The Oort cloud begins where the scattered disk ends (the distance of 2000 AU is conventionally assumed), that is, it does not have a clear boundary - the scattered disk becomes more and more scattered, and gradually turns into a spherical cloud, consisting of the most different bodies revolving in a variety of orbits around the Sun. At a distance of more than 100,000 AU (approximately 1 light year) The Sun can no longer hold anything with its gravity, so the Oort cloud gradually disappears there and the interstellar void begins.

Here is an illustration from Wikipedia, which clearly shows the comparative size of the Oort Cloud and the inner part of the solar system:

For comparison, the orbit of Sedna (Scattered Disk Object, a dwarf planet with a diameter of about 1000 km) is also shown. Sedna is one of the most distant objects known at the moment, the perihelion of its orbit is 76 AU, the aphelion is 940 AU. Opened in 2003. By the way, it would hardly have been discovered if it were not now in the perihelion region of its orbit, that is, at the closest distance to us, although this is twice as far as to Pluto.

What is a comet.

A comet is an icy small body (water ice, frozen gases, a little meteoric matter), and the Oort Cloud mainly consists of these bodies. Although at such vast distances, modern telescopes cannot see objects about a kilometer in size, it is theoretically predicted that there are several trillion (!!!) of small bodies in the Oort Cloud. All of them are potential nuclei of comets. However, with such grandiose cloud sizes, the average distance between neighboring bodies is measured there in millions, and on the outskirts in tens of millions of kilometers.

Everything that is said about the Oort cloud is openly “on the tip of a pen”, since although we are inside it, it is very far from us. But every year, astronomers discover dozens of new comets approaching the Sun. Some of them, the most long-period ones, were thrown into our part of the solar system precisely from the Oort cloud. How could this happen? What exactly brought them here?

The options are:

There is a large planet(s) in the Oort Cloud that disturbs the orbits of small Oort Cloud Objects.
Their orbits were scattered when another star passed near the Sun (at an early stage in the evolution of the Solar System, when the Sun was still inside the star cluster that gave birth to it).
Some long-period comets have been captured by the Sun from a similar "Oort Cloud" of another, smaller star passing nearby.
All of these options are correct at the same time.

Be that as it may, every year new-discovered comets approach their perihelion, both short-period comets that arrived from the Kuiper belt and the Scattered disk (the period of revolution around the Sun is up to 200 years), and long-period comets from the Oort cloud (they, for revolution around the Sun tens of thousands of years are required). Basically, they do not fly too close to the Earth, so only astronomers see them in. But sometimes such guests put on a beautiful space show:

What if..

What will happen if, after all, a comet or an asteroid falls to Earth, because this has happened many times in the past? About this in

Asteroids have always been a danger to the Earth - just look at the example of the disappearance of dinosaurs, but more than 60 million years have passed since then. Throughout its existence, humanity has not encountered such a problem, and, to be honest, they began to think about this for the most part only in the 20th century, when modern powerful telescopes fell into the hands of astronomers. This topic was also addressed by the program of the Ren-TV channel “Military Secret”, in which the announcer in a cheerful voice told the listeners that on May 4, 2062, the Earth will face a global catastrophe, which will be caused by the fall of the asteroid VD17. The scale of the disaster and its likelihood are clearly exaggerated, but the likelihood that humanity can repeat the fate of the dinosaurs really exists.

Currently, the number of potentially dangerous asteroids is estimated at 10 - 20 thousand pieces. But they don't represent mortal danger for humanity. Studies by David Rabinovich and his colleagues at Yale University in the United States allow us to conclude that the estimate of large near-Earth asteroids was greatly overestimated at least twice. If earlier scientists talked about almost 2000 objects with a diameter of more than 1 km, now their number has decreased to 500-1000 pieces. This assessment The number of celestial bodies was obtained using the NEAT asteroid tracking system mounted on the US Air Force telescope atop Mount Haleakala in Hawaii. At present, almost all asteroids of this weight category have been identified, the same applies to asteroids about 10 km in diameter, which are capable of destroying life on the planet. According to a number of scientists, it was the collision of the Earth with a celestial body with a diameter of about 10 km that led to the extinction of dinosaurs and about 70% of the flora and fauna of the planet.

To date, science knows the two most dangerous asteroids - Apophis and VD17. Both asteroids were discovered back in 2004. Apophis is an asteroid with a diameter of 320 meters and a weight of almost 100 million tons. The probability that this celestial body will collide with the earth on April 13, 2036 is estimated as 1:5000. Until recently, this asteroid was among the leaders on the Turin asteroid hazard scale, but observation of the celestial body VD17 for 475 days made it a leader. This asteroid with a diameter of 580 meters and weighing under 1 billion tons has the highest probability of a collision with the Earth known today. Its chances of colliding with our planet in 2102 are estimated at 1:1000.

An asteroid of the size of VD17, upon impact with the Earth, would form a crater with a diameter of 10 km and provoke an earthquake with a force of 7.4 on the Richter scale (in this case, about 10 thousand megatons of energy would be released, which is comparable to the entire earth's nuclear arsenal). Fortunately, we, or rather even the next generation, have another century to take any action on this matter.

If we talk about the Turin scale, then both of these celestial bodies - Apophis and VD17 - have a very low value on the danger scale - 1 and 2 points, respectively. To demonstrate what this means, we present the scale itself below.

Turin Asteroid Hazard Scale

Events with no consequences
0 - the probability of a collision of the Earth with a cosmic body is equal to 0 or less than the probability of a collision of the Earth with a celestial body unknown to science of a comparable size over the next decades. The same assessment is given to celestial bodies that simply burn up in the Earth's atmosphere.

Events that deserve careful scrutiny
1 - The probability of a collision with the Earth is extremely low or equal to the probability of a collision of the planet with an unknown celestial object of the same size.

Close attention of astronomers, events worthy of concern
2 - a celestial body will approach the Earth, but a collision will be unlikely.
3 - a fairly close approach to the planet with a collision probability of 1% or more. The collision threatens the planet with local destruction.
4 - a fairly close approach to the planet with a collision probability of 1% or more. Collision with the Earth threatens regional destruction.

Earth threatening developments
5 - a fairly close approach to the planet with a serious probability of collision, which may be accompanied by regional destruction.
6 - a fairly close approach to the planet with a serious probability of a collision that can provoke a global catastrophe.
7. - a fairly close approach to the planet with a very high probability of collision, can cause a catastrophe on a global scale.

Inevitable Collisions
8 - collision of the Earth with a celestial body, causing local destruction (such events occur once every 1000 years)
9 - collision of the Earth with a celestial body, which will cause global destruction on the planet (such events occur once every 1000-100,000 years)
10 - collision of the Earth with a celestial body, which will lead to a global catastrophe (such events are recorded once every 100,000 years or more).

Despite such a low probability of collision with two known to science asteroids should not be discounted by other, smaller ones, with a diameter of 100 to 300 meters. The fall of such a heavenly gift to Earth may result in the loss of some big city. And in this issue the efficiency of detecting such celestial bodies comes first. It is very important not to “oversleep the catastrophe”.

Asteroid impact crater in the Arizona desert

So, the asteroid DD45 was discovered on February 28, 2009 and after three days it was dangerously close to the Earth. Asteroid AL30, three hours after its discovery, flew at an altitude of 130,000 km., That is, below orbit artificial satellites Earth. There were cases when astronomers discovered a dangerous object after the danger. So, on March 23, 1989, astronomers discovered the 300-meter asteroid Asclepius, which crossed the orbit of our planet at a point where the Earth was only 6 hours ago. The asteroid was discovered after it had departed from Earth. Therefore, the main danger is not that an asteroid measuring 300 meters or more will collide with the Earth, it is quite small, but that it will be detected too late.

Not only in the United States, but also in our country, they are working on a solution to this problem. The process of countering the asteroid threat includes three components: 1) regular search for new asteroids and monitoring of objects already known to scientists that pose a threat to the planet; 2) designing means for observing and actively counteracting asteroids; 3) development of accurate and reliable countermeasures.

Vladimir Degtyar, corresponding member of the Russian Academy of Sciences, believes that at the 2nd and 3rd stages it would be possible to use the Kapkan universal spacecraft, which is capable of either changing the orbit of a celestial body or destroying it, and for observation and research characteristics of the asteroid, use the Kaissa reconnaissance spacecraft. The development of these devices in our country is underway.

The homing, high-precision impact spacecraft "Kapkan" consists of a homing head, an engine, orientation and stabilization equipment. It can be equipped with one shock or a variable number of shock modules separated from the apparatus, each of which has its own propulsion system. After detecting an asteroid approaching the Earth, "Kapkan" enters the specified trajectory. The onboard means of the spacecraft set the parameters of the movement of the celestial body and make adjustments to the spacecraft's flight path. Later, the impact blocks are separated, the ship's equipment captures the consequences of an impact on a celestial body and transmits them to Earth.

The main problem is how to make sure that "Kapkan" is at the right time in right place, because the smaller the size of the asteroid, the more the requirements for its detection range and interception speed increase. Prelaunch preparation should take less than two days. The task of how to deliver the Kapkan to the asteroid is planned to be solved with the help of promising launch vehicles: to asteroids with a diameter of 600-700 meters - using the Rus-M rocket, to asteroids with a diameter of up to 300 meters - using the Soyuz-2 rocket ".

According to the estimates of the specialists of JSC "GRC Makeev", the amount of expenses for the creation of the necessary spacecraft and their adaptation to rocket and space complexes will cost approximately 17 billion rubles. and will take about 10 years. The money is large enough, but not comparable to the possible costs of restoring infrastructure damaged by some random asteroid.

Sources used:
www.nationalsafety.ru/n44319
www.grani.ru/Society/Science/m.102596.html
www.galspace.spb.ru/index65-3.html