The closest threat from space to the earth. Threat from space

On February 15, five years have passed since the appearance of a large meteoroid in the sky over Chelyabinsk, which caused a commotion in the city and attracted the interest of astronomers around the world. What happened that day? Could something like this happen again? What does humanity do and can do to ensure that such events, at least, do not occur suddenly, and that we, as a maximum, learn to fend off such threats? With these questions, the editors N+1 turned to the astronomer Leonid Yelenin, an employee of the Institute of Applied Mathematics of the Russian Academy of Sciences, for whom the incident over Chelyabinsk was of particular importance.

February 15, 2013 began unexpectedly for me - at 7:30 in the morning I got a call from one of the government agencies with the question: “What happened over Chelyabinsk?” When it came to understanding what had happened, the main question became different: why didn’t we find this body in advance? The piquancy of the situation was added by the fact that on the same day the well-known near-Earth asteroid 2012 DA14 was supposed to fly past the Earth, but at a safe distance from it, and the day before the events described, speaking at a press conference, I assured the audience that not a single of the known asteroids in the near future does not threaten us. The very first cursory analysis of data from video cameras showed that the fireball had nothing to do with asteroid 2012 DA14, and it became clear why this meteoroid crept up on us unnoticed ... But first things first.

To begin with, let's figure out what kind of objects they are, where they come from, how they are detected, and why the Chelyabinsk guest could not physically be detected by existing means of controlling outer space.

Telescopes at the ready

The first near-Earth asteroid (NEA) was discovered in 1898. Subsequently, he received the number 433 and the name - Eros. Yes, yes, it's that asteroid from The Expanse. At the time, its orbit seemed unique, with most asteroids orbiting the Sun in the Main Asteroid Belt, between the orbits of Mars and Jupiter.

After about 100 years, a revolution took place in the field of image capture - photographic plates went down in history, and CCD cameras began to be introduced in their place. The transition from analog information to "digital" revolutionized astronomy, including in the field of positional observations of small bodies of the solar system, which include asteroids and comets. The new technique made it possible to quickly and with high accuracy determine the coordinates of celestial objects, calculate their orbits and automate the process of detecting new objects on the received frames, because earlier this was done manually on devices called blink comparators.

Gradually, astronomers began to understand that objects like Eros are quite common in the solar system and that, according to the theory of probability, they can collide with planets. This was only the first step towards understanding the problem of the asteroid-comet hazard (ACH).

In 1980, scientists - Alvarez's father and son - formulated the theory of the collision of the Earth with a large celestial body (8–10 kilometers in diameter) in the distant past and linked the formation of the giant Chicxulub crater in the Gulf of Mexico with the extinction of dinosaurs. Further more. So, in 1983, the newly discovered comet C / 1983 H1 (IRAS-Araki-Alcock) flew just 4.67 million kilometers from the Earth. The size of its core was comparable to the body that collided with the Earth 65 million years ago.

The last straw was the collision of comet P/1993 F2 (Shoemaker-Levy 9), or rather a chain of its fragments, with Jupiter. The comet was discovered in 1993, already torn apart by the gravity of the giant planet, and the question of a collision with the planet was only a matter of time. On July 7, 1994, 21 comet fragments, each up to two kilometers in size, entered Jupiter's atmosphere. The total energy release was about 6 million megatons, which is 750 times more than the entire nuclear potential accumulated on Earth!

Figure 1. Number of near-Earth asteroids (NEA) discovered in recent decades. Red color indicates objects with a diameter of a kilometer or more, orange - 140 meters or more, blue - all the rest.

After all these events in the United States, a state program was adopted to search for dangerous celestial bodies approaching the Earth. In 1998, the first survey telescope took up duty. Within a few years, several more tools began to work on this topic, and the result was not long in coming. Figure 1 shows the statistics of NEA discoveries since 1980, which speaks for itself.

At the moment, several dedicated instruments with a primary mirror diameter of up to 1.8 meters are working on the subject of ACH. Many telescopes that started their work 20 years ago have been modernized - they have been equipped with new colossal CCD cameras. For example, the Pan-STARRS CCD chip mosaic is half a meter in diameter. The question is brewing: well, now, would we be able to open the Chelyabinsk meteoroid in advance? Not! And that's why.

The trajectory of the meteoroid over Chelyabinsk

hard to spot

All near-Earth asteroids are divided into three families, depending on their orbit. All of them have aphelia (the point of the orbit farthest from the Sun) outside the Earth's orbit, so they can be detected. But scientists asked themselves the question: are there any similar objects circling the Sun inside the Earth's orbit and dangerously approaching our planet near its aphelion?

If the orbit of a celestial body is inside the earth's orbit, then it is quite difficult to observe it, even if it is a planet. Venus is called the "morning star" for a reason. It is visible in our sky at dusk, in the evening or in the morning. But this is a very bright object, but how to detect small asteroids in the not yet dark, twilight sky? Such an experience was set. The telescope, mounted high in the mountains, was aimed at the area above the horizon, when the Sun was already sinking behind it. The penetration of telescopes (the ability to detect dim objects) in a bright sky is catastrophically reduced, but even under such conditions, several objects were discovered that were attributed to a new family of near-Earth asteroids. This experience showed that if we do not see some objects, this does not mean that they do not exist (observational selection effect).

I will immediately answer the question about the use of radio telescopes. Yes, they can work during the day, but at the moment their radiation pattern (angle of view) is very small and does not allow searching for objects at large distances. Now, to locate asteroids, optical support is often needed - telescopes refine the orbit of a celestial body and a radio telescope is aimed at already specified coordinates.

The Chelyabinsk meteoroid did not belong to this family of internal NEAs (the Atira family), but approached us from the side of the Sun, and this was the main reason that it was not detected. Another reason is related to its small size. Before entering the atmosphere, its diameter was approximately 17 meters. The characteristic lead time for detecting objects of this size is less than a day, when they come very close to the Earth and modern telescopes can detect them.

By the way, the Chelyabinsk event quite strongly shook the minds of scientists involved in ACH problems. Previously, it was believed that an object less than 50–80 meters in diameter would not be able to cause much harm to people, as it would burn up in the atmosphere. The events over Chelyabinsk showed that this was not the case. All the destruction was caused not by the collision of the body itself with the Earth's surface, but by an air explosion at an altitude of about 19 kilometers. Let me remind you that more than a thousand people suffered. If this happened over densely populated areas of Europe or Japan, there would be significantly more victims. So now scientists understand that the search for decameter-sized asteroids (tens of meters across) is an important task for ACH.

For such a search, they began to attract large telescopes working on astrophysical and cosmological problems. For example, a modernized 4-meter telescope that searches for dark energy is the Dark Energy Camera (DECam). In a few years, a new generation survey telescope, the Large Synoptic Survey Telescope (LSST), with a main mirror diameter of 8.3 meters, should be launched in Chile! This tool will greatly expand the detection of small near-Earth objects. But all this will not solve the problem of internal NEAs.

Figure 2. Libration points (Lagrange points). Points L1, L4, L5 are especially convenient for moving to them and assessing the threat to the Earth from asteroids flying towards it.

To solve it effectively, it is necessary to launch search telescopes into space, and not just into space, but away from the Earth. For example, to libration points (Lagrange points) L1, L4, L5 (Figure 2). In this case, we will look at the Earth as if from the side, which will allow us to detect dangerous objects approaching our planet from the side of the Sun. According to theoretical calculations, the placement of spacecraft in the orbit of Venus or Mercury will give even greater detection efficiency.

The technical implementation of such projects will be complicated by the need to transfer large amounts of data over long distances. For point L1, this is 1.5 million kilometers, for L4 / L5 - 150 million kilometers, but for the orbit of Venus, it ranges from 38 to 261 million kilometers. Here you need to find a balance between the two approaches. What is better, to transmit "raw" frames to Earth and already here, on powerful computers, to squeeze the maximum information out of them - in our case, to detect even the dimmest objects - or to transmit only measurements, and carry out all the simplified processing on board? Most likely, a symbiosis of both approaches will be applied. And this is just one of the many complex technical challenges that scientists and engineers will have to solve.

Theoretical studies of such missions are underway, including in Russia. Only after we can massively detect internal NEAs and study their population, we will be able to close one of the issues of the ACH in terms of detecting dangerous objects. But that's not all. Okay, you ask, we have detected an object flying on a collisional trajectory towards the Earth, and what's next?

Microscopic studies of the Chelyabinsk meteorite

Even harder to knock down

Speaking realistically, so far we can only calculate the time and place of the fall. That is, notify the special services and try to evacuate the population from the dangerous area. To do this, it is necessary to increase the characteristic lead time from several hours to several days. If we talk about parrying the threat, then everything is not so simple. If this is an emergency and danger threatens us in the very near future, then the choice is small - it is either a purely kinetic effect (hit with a blank), or an explosive one, coupled with a kinetic one (we deepen the charge and undermine it).

Everything seems to be beautiful and even quite realizable. We have already successfully bombarded small bodies, there is a charge, interceptor carriers on duty can be created, but there are not a few “buts”.

First, this approach concerns only comparatively small objects. The good news is that we already know the vast majority of large NEAs and do not pose a real threat on the horizon of a couple of hundred years. But there are still unknown comets that, as we see, can approach the Earth.

Secondly, in order to get into an object, one must know its orbit well, and this requires a long observation time (observation arc). If the object is detected a few days before the collision, even if our interceptor is under fallow, then we may not get there.

And thirdly, the methods described above are not controlled - that is, by destroying one large object, we can get a cloud of fragments that will enter the atmosphere, and not all of them will burn out. And then there is the question of what is better: one large object or a swarm of its fragments. Or we can kinetically move the asteroid not as we would like, moving it, for example, into an orbit with an even greater probability of a collision. Since we are not writing a script for a new blockbuster, things may not go as planned...

If an object is dangerous for us in the medium term, over an interval of decades, then we can use the methods of soft and, not least, controlled impact. To an unprepared person, they may seem rather strange, but they can really work if we have dozens of years left. For example, we can place a small spacecraft near the asteroid, which will attract the asteroid - just like the asteroid will attract the apparatus, but, of course, with greater force, because a huge block is much more massive. In this case, we can very accurately calculate the impact and predictably, very slowly, change the orbit of a celestial body.

You can land a spacecraft on the surface of an asteroid and change its orbit with thrusters. Landing on an asteroid or comet nucleus is no longer a fantasy - it has already been implemented. You can even paint an asteroid! Yes, yes, paint one side of the asteroid white so that it reflects sunlight, while the second, unpainted side heats up, radiating thermal energy that can give the asteroid additional acceleration (the Yarkovsky effect). Knowing the shape of the asteroid and the parameters of its rotation around its axis, it is possible to calculate exactly how it needs to be colored in order to achieve the desired result.

This is a brief overview of the issues of ACH, although, of course, this topic is much broader and deeper. There are those who say that this problem does not deserve attention, because the probability of a major collision is very small. Yes, this is true, and the task of real scientists is not to scare, but to warn. Even if the probability is really very small, but the price of inaction is millions and billions of lives, and maybe the fate of the entire civilization. Humanity has everything in order not to follow the sad path of dinosaurs (although for us the fall of a celestial body in the Gulf of Mexico turned out to be a happy event - the first mammals then pulled out their lucky ticket).

Therefore, we need to do everything to preserve our peace, and this applies, of course, not only to the asteroid-comet hazard. Good luck to everyone and look at the night sky more often - it is very beautiful and fraught with many more mysteries that we have to solve!

Leonid Yelenin

In the beginning, we will conduct a general description of the cosmos, as well as its objects that can directly pose a threat to planet Earth. "Cosmos" in Greek means order, structure, harmony (in general, something ordered). Philosophers of Ancient Greece understood the word "cosmos" as the Universe, considering it as an ordered harmonious system. Space was opposed to disorder, chaos. http://www.astronet.ru/ The concept of "cosmos" first included not only the world of heavenly bodies, but also everything that we encounter on the surface of the Earth. More often, the cosmos is understood as the Universe, considered as something unified, subject to general laws. This is where the name of cosmology comes from - a science that tries to find the laws of the structure and development of the Universe as a whole. In the modern sense, the cosmos is everything that is outside the Earth and its atmosphere.

The nearest and most accessible area of ​​outer space for research is near-Earth space. It was from this area that human space exploration began, the first rockets visited it and the first satellite routes were laid. Flights of spaceships with crews on board and the astronauts going directly into outer space have significantly expanded the possibilities for exploring "near space". Space research also includes the study of "deep space" and a number of new phenomena associated with the influence of weightlessness and other cosmic phenomena. factors on the physical-chemical. and biological processes.

What is the physical nature of near-Earth space? The gases that form the upper layers of the earth's atmosphere are ionized by the UV radiation of the Sun, i.e., they are in the state of plasma. The plasma interacts with the Earth's magnetic field in such a way that the magnetic field exerts pressure on the plasma. With distance from the Earth, the pressure of the plasma itself falls faster than the pressure exerted on it by the terrestrial magnetic field. As a result, the plasma shell of the Earth can be divided into two parts. The lower part, where the plasma pressure exceeds the magnetic field pressure, is the ionosphere. Above lies the magnetosphere - the region where the pressure of the magnetic field is greater than the gaseous pressure of the plasma. The behavior of plasma in the magnetosphere is determined and regulated primarily by the magnetic field. field and is fundamentally different from the behavior of an ordinary gas. Therefore, unlike the ionosphere, which is attributed to the upper atmosphere of the Earth, the magnetosphere is usually attributed to the cosmic. space. By physical nature, near-Earth space, or near space, is the magnetosphere. In the magnetosphere, the phenomenon of the capture of charged particles by the Earth's magnetic field becomes possible, which acts as a natural magnetic trap. This is how the Earth's radiation belts are formed.

The assignment of the magnetosphere to outer space is due to the fact that it closely interacts with more distant space objects, and above all with the Sun. The outer shell of the Sun - the corona - emits a continuous stream of plasma - the solar wind. Near the Earth, it interacts with the earth's magnetic field (for a plasma, a sufficiently strong magnetic field is the same as a solid body), flowing around it, like a supersonic gas flow around an obstacle. In this case, a stationary outgoing shock wave arises, the front of which is located at a distance of approx. 14 Earth radii (~100,000 km) from its center on the day side. Closer to the Earth, the plasma that has passed through the wave front is in chaotic turbulent motion. The transitional turbulent region ends where the pressure of the regular magnetic field of the Earth exceeds the pressure of the turbulent plasma of the solar wind. This is external. the boundary of the magnetosphere, or magnetopause, located at a distance of approx. 10 Earth radii (~60000 km) from the center of the Earth from the day side. From the night side, the solar wind forms the plasma tail of the Earth (sometimes it is inaccurately called the gas tail). Manifestations of solar activity - flares on the Sun - lead to the ejection of solar matter in the form of individual plasma bunches. Clots flying in the direction of the Earth, hitting the magnetosphere, cause it for a short time. compression followed by expansion. This is how magnetic storms arise, and some particles of the bunch penetrating through the magnetosphere cause aurora, disruption of radio and even telegraph communications. The most energetic bunch particles are registered as solar cosmic rays (they make up only a small part of the total cosmic ray flux).

Briefly describe the solar system. Here are the nearest targets of space flights - the Moon and planets. The space between the planets is filled with plasma of very low density, which is carried by the solar wind. The nature of the interaction of the solar wind plasma with the planets depends on whether or not the planets have a magnetic field.

The family of natural satellites of the giant planets is very diverse. One of Jupiter's moons, Io, is the most volcanically active body in the solar system. Titan, the largest of Saturn's moons, has a fairly dense atmosphere, almost comparable to Earth's. A very unusual phenomenon. and the interaction of such satellites with the surrounding plasma of the magnetospheres of the mother planets. The rings of Saturn, consisting of stone and ice blocks of various sizes, down to the smallest dust particles, can be viewed as a giant conglomerate of miniature natural satellites.

Comets move in very elongated orbits around the Sun. Comet nuclei are composed of individual rocks and dust particles frozen into a block of ice. This ice is not quite ordinary; in addition to water, it contains ammonia and methane. Chem. The composition of cometary ice resembles that of the largest planet, Jupiter. As the comet approaches the Sun, the ice partially evaporates, forming the comet's gigantic gaseous tail. Comet tails are turned away from the Sun, because they are constantly exposed to radiation pressure and the solar wind.

Our Sun is just one of many stars that form a giant star system - the Galaxy. And this system, in turn, is only one of many other galaxies. Astronomers are accustomed to refer the word "Galaxy" as a proper name to our star system, and the same word as a common noun - to all such systems in general. Our Galaxy contains 150-200 billion stars. They are located in such a way that the Galaxy has the form of a flat disk, in the middle of which, as it were, a ball is inserted with a diameter smaller than that of the disk. The sun is located on the periphery of the disk, practically in its plane of symmetry. Therefore, when we look at the sky in the plane of the disk, we see a luminous band in the night sky - the Milky Way, consisting of stars belonging to the disk. The very name "Galaxy" comes from the Greek word galaktikos - milky, milky and means the system of the Milky Way.

The study of the spectra of stars, their movements, and other properties, in comparison with theoretical calculations, made it possible to create a theory of the structure and evolution of stars. According to this theory, the main source of energy for stars is nuclear reactions occurring deep in the interior of the star, where the temperature is thousands of times higher than on the surface. Nuclear reactions in space and the origin of chem. elements are studied by nuclear astrophysics. At certain stages of evolution, stars eject part of their matter, which joins the interstellar gas. Especially powerful emissions occur during stellar explosions, observed as bursts of supernovae. In other cases, stellar explosions can form black holes - objects whose matter falls towards the center at a speed close to the speed of light, and, due to the effects of the general theory of relativity (the theory of gravitation), seems to be frozen in this fall. Radiation cannot escape from the depths of black holes. At the same time, the matter surrounding the black hole forms the so-called. accretion disk and, under certain conditions, emits X-rays due to the gravitational energy of attraction to the black hole.

So, what threatens space?

Among natural disasters, a special place belongs to cosmogenic disasters, given their large scale and the possibility of severe environmental consequences. There are two types of cosmic catastrophes: impact-collision (USC), when parts of the spacecraft that are not destroyed in the atmosphere collide with the Earth's surface, forming craters on it, and air-explosive (AEC), in which the object is completely destroyed in the atmosphere. Combined catastrophes are also possible. An example of USC is the Arizona meteorite crater with a diameter of 1.2 km, formed about 50 thousand years ago as a result of the fall of an iron meteorite weighing 10 thousand tons, and the IHC is the Tunguska catastrophe (a meteorite with a diameter of 50 m was completely dispersed in the atmosphere).

The consequences of catastrophes arising from the impact of space objects on the Earth can be the following:

Natural and climatic - the occurrence of the effect of nuclear winter, disruption of the climatic and ecological balance, soil erosion, irreversible and reversible impacts on flora and fauna, atmospheric pollution with nitrogen oxides, abundant acid rain, destruction of the ozone layer of the atmosphere, massive fires; death and defeat of people;

Economic - the destruction of economic facilities, engineering structures and communications, including the destruction and damage to transport routes;

Cultural and historical - the destruction of cultural and historical values;

Political - a possible complication of the international situation associated with the migration of the population from the places of the disaster, and the weakening of individual states.

Affecting factors as a result of exposure to CO.

The damaging factors and their energy in each particular case depend on the type of catastrophe, as well as on the place where the space object fell. They are largely similar to the damaging factors characteristic of nuclear weapons (with the exception of radiological ones).

These are:

Shockwave:

Air - causes destruction of buildings and structures, communications, communication lines, damage to highways, damage to people, flora and fauna;

In water - destruction and damage to hydraulic structures, surface and underwater vessels, partial damage to marine flora and fauna (at the disaster site), as well as natural disasters (tsunamis) leading to destruction in coastal areas;

In the ground - phenomena similar to earthquakes (destruction of buildings and structures, engineering communications, communication lines, highways, death and injury of people, flora and fauna).

· Light radiation leads to the destruction of material values, the emergence of various atmospheric and climatic effects, the death and injury of people, flora and fauna.

· An electromagnetic pulse affects electrical and electronic equipment, damages communication systems, television and radio broadcasting, etc.

Atmospheric electricity - the consequences of the damaging factor are similar to the effects of lightning.

· Poisonous substances - this is the occurrence of gas contamination of the atmosphere in the disaster area, mainly nitrogen oxides and its toxic compounds.

· Aerosol pollution of the atmosphere - the effect of this is similar to dust storms, and with a large scale catastrophe, it can lead to a change in climatic conditions on Earth.

Secondary damaging factors appear as a result of the destruction of nuclear power plants, dams, chemical plants, warehouses for various purposes, storage facilities for radioactive waste, etc.

Danger for the planet Earth is represented by such space "guests" and phenomena as: asteroids (small planets), comets, meteorites, viruses brought by space bodies from space, disturbances in the sun, black holes, the birth of supernovae.

The Earth constantly encounters small cosmic bodies. It is more correct to call these meetings collisions, because our planet moves in orbit at a speed of about 30 km / s, and a celestial body also flies towards the Earth in its orbit at a speed of the same order. If the body is small, then, crashing into the upper layers of the earth's atmosphere, it is enveloped in a layer of hot plasma and completely evaporates. Such particles in science are called meteors, and among the people "shooting stars". The meteor suddenly flashes and draws a rapidly fading trail in the night sky. Sometimes there are "meteor showers" - the mass appearance of meteors when the Earth meets meteor swarms, or streams. The Perseid swarm is well known, observed in the region of the constellation Perseus. The associated "starfalls" are celebrated annually on nights close to August 12. And every 33 years, in mid-November, the Leonids meteor shower, observed in the region of the constellation Leo, "sheds" on Earth. The last time this event happened on November 16-18, 1998. The meeting of the Earth with a larger body looks completely different. It evaporates only partially, penetrates into the lower layers of the atmosphere, sometimes breaks into pieces or explodes, and, having lost speed, falls to the earth's surface. Such a body in flight is called a fireball, and what flew to the surface is called a meteorite.

Back in the 18th century, small planets - asteroids - were first discovered with the help of a telescope. By our time, several hundred of them have already been discovered, and the orbits of about 500 of them cross the Earth's orbit or approach it dangerously. It is possible that in fact there are more such asteroids - several thousand. Comets can also pose a considerable danger to the Earth: in the history of mankind, apparently, there were about 2000 of them. And the Earth is constantly encountered with small cosmic bodies. "Science and Life" No. 8, 1995; No. 3, 2000 Almost 20 thousand meteorites fall annually on the Earth, but the vast majority of them are of very small size and mass. The smallest - weighing only a few grams - do not even reach the surface of our planet, burning up in the dense layers of its atmosphere. But already 100 grams reach and are capable of causing considerable harm to both a living being and a building or, for example, a vehicle. But, fortunately, according to statistics, more than 2/3 of meteorites of any size fall into the ocean, and only fairly large ones can cause a tsunami. The fall into the ocean of small cosmic bodies leads to much less dangerous consequences than when falling on land, as a result of which craters appear on Earth.

Of the relatively large craters on Earth, more than 230 are known. It is assumed that the fall of large cosmic bodies to the Earth led to the death of a significant part of the biota. And in particular - to the death of 2/3 of living organisms, including dinosaurs, which occurred 65 million years ago as a result of a large asteroid or comet nucleus colliding with the Earth. It is possible that the appearance of a crater 180 km in diameter on the Yucatan Peninsula is connected with this event: the age of this crater is 64.98 ± 0.04 million years. But such serious catastrophes are rare and are not expected in the foreseeable future, while collisions with the Earth of meteorites, including large ones, and therefore capable of bringing considerable disasters to mankind, are quite probable. Optimism, however, is inspired by the fact that modern science is quite able not only to predict, but also to prevent such collisions. After all, astronomers are able to calculate the trajectory of the flight of a cosmic body for several years ahead, and this is quite enough to find a way to change it or, in extreme cases, destroy the meteorite itself A. Mikisha, M. Smirnov. Terrestrial catastrophes caused by the fall of meteorites. "Vestnik RAS" Volume 69, No. 4, 1999, pp. 327-336

According to statistics, collisions of the Earth with an asteroid up to one and a half kilometers in diameter can occur approximately once every 300 thousand years. The more time our world has lived without encounters with "space bombs", the higher the likelihood of such an event in the future.

In pictures taken from space, about 4 thousand strange ring structures are visible on the body of the planet from tens to several thousand kilometers across. This is nothing but traces of hits of "space projectiles". Of course, in an ongoing meteor shower, not very large (by space, of course, standards) bodies are more common. For example, the mass of the Sikhote-Alin meteorite that fell in the Far East in 1947 reached 100 tons. A meteorite that crashed into the Gobi Desert weighed 600 tons. But even from a meeting with such "kids" very noticeable scars and "pockmarks" remain on the body of the Earth. So, a pebble that once fell in Arizona left a crater with a diameter of almost one and a half kilometers and a depth of 170 meters. .

Stones wandering in space now and then whistle next to our planet, "like bullets at the temple."

From official sources:

1932 The Apollo asteroid attacked Earth. A stone "bomb" with a diameter of one kilometer missed by 10 million kilometers. Quite a bit on a cosmic scale.

1936 Asteroid "Adonis" emerged from the darkness of space already at a distance of 2 million kilometers.

1968 The micro-planet Icarus rushed dangerously close.

1989 An asteroid with a diameter of about a kilometer crossed the Earth's orbit, having missed our planet by only six hours.

In May 1996, at a speed of 20 kilometers per second, a five-hundred-meter diameter asteroid flew by at a speed of 20 kilometers per second ... If such a crumb had collided with the Earth, the explosion power would have reached about 3,000 megatons of TNT equivalent. And the consequences are such that the continued existence of our civilization became very doubtful.

In 1997, two more large asteroids crossed the Earth's orbit... One cannot say that humanity is so defenseless against the meteorite danger. It is estimated that the combat missiles that exist today can meet on approach to the Earth and destroy any cosmic body with a diameter of up to a kilometer. The plan for such an interception originated back in the 60s, when the Icarus asteroid dangerously approached our planet.

Recently this issue has been brought up again. The threat from outer space was discussed at the International Conference "Asteroid Hazard" held in St. Petersburg. The same questions were raised at the "Space Defense of the Earth" symposium held in the Russian secret city of Snezhinsk. In a short period of time, another representative meeting was held (this time in Rome), where it was announced the creation of a "space guard" - an international organization that puts before

Space protection is necessary, and it must be multifaceted, since the Earth must be protected not only from "heavenly stones", but also from other misfortunes supplied to us by space.

The mystery of the origin of new viruses has led some scientists to suggest that this scourge comes to us from outer space. The danger of such "gifts" can hardly be overestimated. Recall at least the legendary "Spanish flu" (an outdated name for the flu, which existed at the beginning of the 20th century). During the Spanish flu pandemic of 1918-1919, about 20 million people died from this disease. Death occurred as a result of acute inflammation and pulmonary edema. Today, scientists believe that it was not the flu at all that led to so many victims, but some other, still unknown disease.

In those years, virology was in its infancy and could not unambiguously identify the causative agent of the disease. In some laboratories around the world, tissue samples of people who died during the Spanish flu pandemic have been preserved, but studies carried out many years later did not find microbes there that would have such deadly properties.

Now it is planned to exhume the corpses on the island of Svalbard, where at the beginning of the 20th century there was an operating mine and in the permafrost the bodies of miners who died during the pandemic could retain an unknown virus. Virologists are pushing for these studies because epidemics happen in cycles and doctors need to know exactly the true nature of the "Spanish flu" of the beginning of the century in order to prevent deaths if the disease returns when the Earth once again crosses a cloud of cosmic dust, possibly infected with viruses.

The sun also gives us "gifts". Scientists recall the catastrophic event that occurred in March 1989 in Quebec. After a powerful solar flare, a stream of particles reached the surface of our planet, causing a man-made disaster in Canada - all electricity generators went out of order there and six million people were left without heat and light for almost a day.

Many scientists argue that the current activity of the Sun creates the possibility of a recurrence of the "Quebec cataclysm" in the very near future. Several American space satellites have already allegedly failed due to powerful solar emissions rushing towards Earth.

However, in the department of solar physics of the Astronomical Institute. Sternberg is consoled by mankind, saying that the situation is within the normal range and nothing supernatural is expected. Yes, several satellites have been damaged, but the noise that is raised around this event, again, is caused more by a desire to get money for their research programs than by a real danger.

However, the date of a possible future meeting with the next "space bomb" has already been determined - August 14, 2126. The forecast was made by the respected American astronomer Brian Marsden. He predicted a collision with Comet Swift-Tatla. We are talking about an ice mountain with a diameter of 10 kilometers. Its impact on the Earth will be equivalent to the explosion of 100 million powerful atomic bombs. We will believe that by this time the earthly civilization will surely be able to protect itself from any comets and meteorites.

We must not forget that our planet is the same stone projectile that rushes through space at great speed. And on this way through the expanses of the Universe, our Earth is waiting for the most unexpected and dangerous surprises. Experts talk about the fatal sectors of the Galaxy, where there are miniature "black holes", scattered clouds of poisonous gases, "bubbles" with altered spatial and temporal characteristics...

Unfortunately, there is not enough funding for space defense and research in this area, even in civilized countries.

In particular, although the American space agency NASA is able to detect almost all asteroids that threaten the Earth, the department does not have enough funds for these purposes. To detect approximately 20,000 asteroids and comets potentially dangerous to the planet (which is approximately 90% of the possible ones), NASA needs a billion dollars by 2020. Back in 2005, the US Congress instructed the agency to develop a plan to track the trajectories of most asteroids and comets.

In addition, scientists had to identify the most dangerous of them and propose a project for their evasion from the planet. NASA currently tracks mainly the largest space objects, which are more than a kilometer in diameter. However, at least 769 known asteroids and comets, whose diameter does not exceed 140 meters, are observed less closely. Although scientists note that even small objects pose a threat to the Earth, since their explosions near the planet as a result of heating can lead to significant destruction. To fully track the movement of asteroids, NASA offers two options: either build a new $800 million ground-based telescope, or launch a $1.1 billion space-based infrared telescope. The US administration considers both options too expensive http:// Polit.ru.

Thus, space is full of dangers to life, especially asteroids, meteorites, comets threatening to crash into the Earth. The number of dangers increases with distance into space: for example, supernovae, which emit enough radiation to break through the protective ozone layer of the Earth. A new study has shown that for this to happen, the former star must be 25 light-years from Earth - so close that this can only happen once or twice in a billion years. Previously, this risk was thought to be much higher. Physicist Malvin Ruderman of Columbia University calculated in 1974 that cosmic and gamma rays from a supernova 50 light-years away could destroy most of the ozone layer in decades. But the latest estimates from Goddard Space Flight Center's Neil Gerels allow one to breathe a sigh of relief. The scientist used a detailed model of the atmosphere to understand how nitric oxide, a compound catalyzed by supernova radiation, would destroy ozone. It turned out that in order for twice as much ultraviolet rays to penetrate the atmosphere as now, a star must explode at a distance of no more than 25 light years. Today, at such a small distance from the Earth, there is not a single star large enough for it to die, turning into a supernova. Moreover, such stars very rarely approach the solar system, so a supernova can occur here no more than once every 700 million years.

There is a danger from so-called black holes. The famous physicist Stephen Hawking was forced to reconsider his theory of black holes. Previously, it was believed that no object is able to get out of the powerful gravitational field of a black hole. However, later the scientist came to the conclusion that information about these objects that fell into a space hole can be radiated back in a transformed form. This perverted information, in turn, changes the essence of the object. An object "infected" in this way transforms any information about the object that it encounters on its way. Moreover, if the cloud reaches the Earth, then the effect of its impact on the planet will be akin to spilling water on a handwritten ink text, which corrodes words and turns into a mess.

Solar flares are dangerous. An interplanetary shock wave generated by a solar flare, reaching the Earth, causes the aurora, visible even in mid-latitudes. The velocity of the ejected material may be about 908 km/s (observed in 2000). The ejection, consisting of giant clouds of electrons and magnetic fields, reaching the Earth is capable of causing large magnetic storms that can interrupt satellite communications. Coronal mass ejections can carry up to 10 billion tons of electrified gas from the Sun's corona, propagating at speeds up to 2000 km/s. As they become more and more, they envelop the Sun, forming a halo around our star. It may sound ominous, but in fact, such emissions do not pose a danger to people on Earth. The magnetic field of our planet serves as a reliable protective screen against the solar wind. When the solar wind reaches the magnetosphere - the region around the Earth controlled by its magnetic field - much of the material is deflected far beyond our planet. If the solar wind wave is large, it can compress the magnetosphere and cause a geomagnetic storm. The last time such an event occurred in early April 2000.

We think that deep space is distant and unattainable, but in fact, events in this very space could help accelerate the evolution of life on Earth. We ended up here by accident. Evolution could go along a different branch of development; any chances of spontaneous emergence of life are so small that they can be called random. The life of the Earth came about through a chain of random events, strange situations, convenient catastrophes, from ice ages to asteroid impacts - and here we are.

Taking all this for granted, we can understand the history of life only if we choose a wider field of vision. Organisms are shaped by their environment, and these environments are in turn shaped by powerful geological forces such as volcanoes and ice sheets, as well as climate change.

And yet we should expand our horizons even more, throw the net farther away. What if these powerful forces were influenced by even more powerful forces from the wider universe? Could cosmic events in our solar system and even our galaxy have played a role? Should we literally thank our stars for being here?

The most famous example of an evolutionary shift caused by astronomical events is the extinction of the dinosaurs, which was caused by the fall of a giant meteorite 66 million years ago. This hypothesis was first proposed by Luis Alvarez, his son, geologist Walter, and their colleagues in 1980.

The researchers found that the sedimentary rocks that formed around the world during the extinction of the dinosaurs contain large amounts of the rare element iridium. Scientists have suggested that the iridium could come from the dusty debris of a meteorite that crashed into the Earth. In the asteroids that were the most likely source of the iconic meteorite, iridium is much more abundant than on Earth.

How exactly such a fall could have killed the dinosaurs is an open question. But there are quite a few possibilities.

The released energy could cause global forest fires. The researchers calculated that to deliver the required amount of iridium, the meteorite would have to be on the order of 10 kilometers across. The impact of such a monster would release millions of times more energy than a hydrogen bomb. What's more, the dust and debris thrown into the air could block the sunlight and set off a gradual drop in temperature over the next few years.

In 1991, the fall hypothesis received a new boost when scientists discovered an impact crater more than 160 kilometers wide at the Chicxulub site in Mexico's Yucatan Peninsula. Its geological age exactly coincided with the period of extinction.

How exactly the meteorite impact affected the demise of the dinosaurs is not fully understood; there is evidence that they were already close to it. Nevertheless, it is logical to assume that such a powerful event should have left some imprint on evolutionary history. And this discovery has caused concern about the possible fall of a devastating meteorite today.

Also, meteor impacts are not the only explanation for the extinctions that took place 66 million years ago.

Tokuhiro Nimura is a scientist at the Japan Spaceguard Association, which formed to observe near-Earth objects that could hit the planet. In March 2016, Nimura and colleagues suggested that the extinctions, global cooling, and the iridium layer could be caused by the passage of the solar system through a molecular cloud: one of the large clouds of gas and dust in space from which stars form. As dust accumulated in the atmosphere, it formed a haze that reflected sunlight and cooled the planet.

The basic idea goes back to a suggestion made by British astronomer William McCree in 1975. He thought that if the Earth were to pass through an interstellar dust "stripe", it would start an ice age. At the same time, astronomers Mitchell Begelman and Martin Rees noted that such dust could affect the way the particles of the sun enter the atmosphere of our planet, and expose the planet to high doses of radiation, further exacerbating extinctions and climate change.

Now Nimura has resurrected McCree's idea, arguing that the Chicxulub fall was not catastrophic enough to cause all the late Cretaceous extinctions.

However, this is mostly speculation right now.

"The idea struck me as very interesting and plausible, but so far it has not been developed and has no clear supporting evidence," says astronomer Martin Beach of Campion College at the University of Regina in Saskatchewan, Canada.

This 66 million year event was just one of several known "mass extinctions" in which many species across the planet suddenly disappeared.

The largest extinction occurred at the end of the Permian period 252 million years ago, when at least 96% of all life died out on Earth. All modern life descended from the surviving 4%, so it is clear that evolutionary history could have been completely different if that extinction had not happened. When species die off, those given the opportunity evolve and make the most of it, dictating species diversity that would otherwise not exist.

Paleontologists have long debated what caused these mass extinctions.

It is possible that, like smaller population declines, they may be integral to how ecosystems work. Since all life is interconnected, a small shift in one population can cause a domino effect, sending shockwaves through the entire system.

But it is more likely that at least some of the mass extinctions were caused by external influences on the living world.

One such mass extinction occurred at the end of the Triassic period. About half of all species on Earth have disappeared. This event could also be caused by an increase in volcanic activity, climate change, but most likely a meteorite fall.

Such catastrophic events cannot be the result of pure chance, a random comet or asteroid hitting the Earth. Instead, cosmic circumstances may systematically bring such objects closer to our world.

The most famous of these ideas is that the Sun has a dim companion star that is so far away that it has never been directly observed. This star, "Nemesis" or "Death Star", periodically pulls chunks of icy rock from the outskirts of the solar system and sends them to hang out in our neighborhood.

This idea was proposed in 1984 by two teams of astronomers: Daniel Whitmire and Albert Jackson and Mark Davis, Richard Muller and Pete Hut. They all built on a discovery earlier that year that mass extinctions have occurred at regular intervals of about 26 million years over the past 500 million years.

So, perhaps the gravitational pull of Nemesis, which circles the Sun in an orbit 1.5 light years away from us, has disrupted the Oort cloud: a collection of icy objects that are 0.8 to 3 light years beyond the orbit of Pluto, weakly bound by gravity Sun. The Oort Cloud is the source of "long-period" comets that return to the inner solar system every two hundred years or so.

Nemesis must be a tiny star, perhaps a red or even brown dwarf no larger than Jupiter. Therefore, she was never noticed. At this distance, it would be difficult to see even with our most powerful telescopes.

But this is not the only problem with the Nemesis theory.

In a study published in 2010, astrophysicist Adrian Melott of the University of Kansas and paleontologist Richard Bambach of the Smithsonian Institution in Washington, D.C., set out to take a fresh look at fossils using the latest data. They confirmed that mass extinctions happened every 27 million years. But such a picture is too ordinary to fit into the idea of ​​\u200b\u200bNemesis. Such a distant dwarf would inevitably be influenced by other nearby stars, producing a less constant stream of comets.

No, scientists decided. Mass extinction waves must be driven not by a companion star, but by another planet.

In 1985, Whitmire and his colleague John Matese suggested that there could be a relatively small, rocky planet five times the mass of Earth, orbiting far beyond Neptune in the solar system. This planet may be constricting comets, not from the Oort cloud, but from the closer Kuiper belt. This is another ice rock disk at the edge of the solar system, Pluto and its moon Charon are recognized as members. Whitmire and Matese named their hypothetical object "Planet X".

It is possible that we have not yet managed to find another planet in the solar system that is larger than the Earth. Before the New Horizons spacecraft reached Pluto and Charon in 2015, we had some pretty bad pictures of these objects, and we were just beginning to search for larger bodies in the Kuiper Belt. If planet X is dark and does not reflect light, it could well elude our telescopes.

Moreover, in January 2016, astronomers suggested that there could be a ninth planet in the solar system, beyond Neptune, with a mass of 10 Earth. The proposal grew out of sightings of visible Kuiper belt objects that seemed to be alarmed by an unseen influence.

If this planet exists, it is unlikely to do what it claims to be behind planet X. But history shows that we don't know much about our own backyard.

Whitmire, now at the University of Arkansas, decided to take the Planet X hypothesis even further. In 2015, he showed that this idea is consistent with the 27-million-year extinction cycle observed by Melott and Bambach. Moreover, Whitmire says that the second such object is planet Y? - could explain another fluctuation in the fossil record.

This painting was noticed by Richard Muller and Robert Rohde in 2005. They found that the diversity of marine species rises and falls every 62 million years: this fluctuation must be caused either by a change in the rate of extinction or the rate of speciation.

Comet waves caused by "hidden" planets could be the explanation for these patterns, Melott says. But he adds that other, more distant cosmic events may be behind these fluctuations.

In 2007, Melott and his colleague Mikhail Medvedev stated that the 62-million-year pulse could be caused by a regular feature of our solar system's journey through the Milky Way.

Our galaxy is shaped like a dish. As it rotates, the Sun rises and falls on the galactic plane, like a horse on a merry-go-round. These changes in position can change the amount of cosmic rays that stream through the solar system and hit the Earth.

Cosmic rays are high-energy subatomic particles, protons and electrons, flying through space. It is believed that they must be born in high-energy astronomical processes. Some are born in supernovae: stars that explode when their fuel runs out. Others are born in black holes at the centers of other galaxies.

There are various ways in which they may have affected the environment of the Earth and our evolution.

Cosmic rays themselves can be harmful. When they collide with molecules in the air, they create showers of particles that can cause mutations in DNA. Usually it's bad for life. However, low mutation rates can actually increase diversity, make life more diverse.

Cosmic ray collisions can also change the chemical composition of the atmosphere. They can produce electrically charged particles that affect the formation of clouds and hence the climate, or they can destroy the ozone layer that protects the Earth from the sun's harmful ultraviolet rays.

Because many cosmic rays are thought to be created by supernovae within our galaxy, the up and down wobble of our solar system can change the flow of cosmic rays, with all the implications for earthly life.

However, it is rather strange that these effects only appeared among marine fossils. In any case, one would expect that organisms living in the sea are better protected from showers of harmful particles than those living on land.

Even Melott now thinks that this idea cannot explain the 62-million-year cycle in the fossil record. In 2011, he suggested that it could be an innate geological "Earth pulse", possibly related to changes in tectonic activity.

There is a similar pattern of changes in marine sediment composition, Melott says. This is what one would expect from changes in the rate of mountain building and erosion caused by shifts in the movement of tectonic plates.

Death rays from space seem to be a good reason for some of the evolutionary shifts seen in the fossil record.

We are constantly exposed to low levels of cosmic rays. But a single supernova can unleash such a deadly burst of these particles that it sterilizes a planet if it's not lucky enough to be nearby and in the right direction.

Stars go supernova all the time; during this, they can temporarily glow brighter than entire galaxies. Every year we see many supernovae in other galaxies, but in our own galaxy, people last saw a supernova 140 years ago. Another, which was born in 1572, was so bright that the astronomer Tycho Brahe saw it with the naked eye and successfully described it.

Supernova Tycho was safely distant, 7,500 light years away. If such an explosion happened much closer to us, it would be a serious disaster. The earth would be shaved bald in a shower of particles and x-rays and gamma rays.

Has this ever happened?

It is believed that a supernova would have to be within 30 light years to have devastating effects on Earth. There aren't many stars that close to us.

However, in 2002, research by astronomers showed that there could have been 20 supernovae within 420 light-years of Earth in the past 11 million years, from just one group of stars. Such events could well leave imprints in the fossil record.

They definitely left traces in the sedimentary rocks. Supernovae scatter the outer layers of an exploding star into space, including some atoms that are not abundant on Earth.

One such telling supernova product is iron-60, which does not occur naturally on Earth. In 1999, physicists discovered high levels of iron-60 in geological structures deep in the ocean - ferromanganese crusts formed over the past 5 million years. Iron-60 has also been found in lunar soil and appears to have come from two supernovae 320 light-years away, seven and two million years ago, respectively.

The latest explosions seem to have left traces in the fossil record.

In a study published in August 2016, astrophysicist Sean Bishop of the Technical University of Munich and colleagues reported the discovery of iron-60 in fossil iron oxide crystals. These crystals were originally made by bacteria that use magnetic oxide to align with the Earth's magnetic field. Iron-60 began to appear in such fossils in marine sediments formed 2.6-2.8 million years ago.

Life could be disturbed by these supernovae.

X-rays and gamma rays coming from such a distant source are not in themselves a problem. "They don't enter our atmosphere and therefore can't directly lead to sterilization or mass extinctions," Bishop says.

But he also says these rays can create an indirect hazard by damaging the ozone layer. "With the depletion of the ozone layer, as far as we know from the time of the Antarctic ozone hole, ultraviolet light from the Sun will penetrate the Earth's surface and could become a problem for organisms."

According to calculations by astronomer Narciso Benitez and his colleagues, supernovae at such distances have the potential to deplete atmospheric ozone.

What’s more, in a July 2016 study, Melott and colleagues calculated that cosmic rays from supernovae could increase the number of high-energy neutrons and muons reaching the earth, tripling the total radiation dose to terrestrial organisms. This could trigger cancerous mutations and also trigger climate change, scientists say.

2.6 million years, a small mass extinction did take place, at the turn of the Pliocene and Pleistocene epochs. But we can't say for sure that supernovae "had a hand in it."

In fact, there is no direct evidence that supernovae have ever interfered with the evolutionary history of life at all, Bishop says. “After millions of years, it will be incredibly difficult to prove.” For example, there is no way to collect and study fossilized DNA for mutations after such a long period of time, let alone compare it before and after the event.

However, there is another kind of cosmic explosion, even more powerful.

The skies are sometimes torn apart by explosions - gamma-ray bursts: extremely intense explosions that release gamma rays that live from fractions of a second to several hours. Gamma-ray bursts are among the most energetically powerful events in the universe. They are born when particularly powerful stars explode.

Fortunately, gamma-ray bursts have so far only been seen in very distant galaxies. But if one of these were born nearby, the supernova would be fireworks by comparison. To make matters worse, we could hardly have detected its approach in advance, no faster than a couple of hours. Fortunately, Melott says that 10,000 light-year GRBs in the area are born about once every 170 million years.

And although it is quite rare, the Earth has existed long enough to be hit many times. In 2004, Melott suggested that the mass extinction of the end of the Ordovician 440 million years ago could be due to a gamma-ray burst. And everything went according to plan: X-rays and gamma rays severely damaged the ozone layer, triggered global cooling due to the formation of dense smoke from nitrogen oxides in the atmosphere.

Melott argues that the late Ordovician extinction model fits into this picture. For example, shallow-sea marine organisms, which were more exposed to ultraviolet radiation than deep-sea ones, were more affected. In addition, the climate has become noticeably colder.

Could this happen again? The Earth has about two billion years left to live, after which the Sun will expand and make the planet uninhabitable. In a 2011 analysis, Beach calculated that during this time, there could be about 20 supernova events and one nearby gamma-ray burst that would cause harm. But these are slightly disturbing numbers.

In addition, Melott says that we will be able to see supernovae in advance, since we measure the age of nearby stars. The nearest one that could detonate soon - in the next million years - is Betelgeuse in the constellation of Orion. She's too far away to cause any damage.

Beach says it could theoretically be possible to change stars by engineering to avoid catastrophic explosions. “If a civilization knew that a supernova was about to burst in its vicinity, one of the options for survival would be to try some kind of super-engineering project.”

For example, they could deflect the explosion by causing the star to lose mass, or by mixing in some material that could slow its collapse. “How such a project could be physically implemented, I don’t know, but the physics of this situation and what needs to be done to extend the life of a star are quite well understood.”

Beach suggests that stars that threaten to go supernova could be good places to look for aliens. If such a star begins to behave strangely, this may be a sign of deliberate change in it.

The cosmic threats to life on Earth may be even more exotic.

In the 2015 book Dark Matter and Dinosaurs, physicist Lisa Randall of Harvard University suggested that a mysterious cosmic substance - dark matter - could be the absolute killer of the dinosaurs.

Dark matter does not interact with light, so we cannot see it directly. It affects ordinary matter only through gravity: it has mass, so it attracts matter, like any ordinary substance. We don't know what dark matter is. No one has ever found a single particle of it. But most physicists and astronomers are sure of its existence. Without it, galaxies would not rotate so fast and would not fall apart. Dark matter outnumbers ordinary matter by a factor of five. It is believed that it surrounds each galaxy with a spherical halo.

Randall suggested that certain dark matter is different from the rest.

This "exotic dark matter" can sense another force, like gravity, a type of electromagnetic force that allows ordinary matter to interact with light. This exotic dark matter could have formed a disk in the galactic plane, and the passage of the solar system through this disk could have disrupted the comet's path in the Oort cloud, causing it to hit Earth 66 million years ago.

Biologist Michael Rampino of New York University expanded on this idea. In a study published in 2015, he suggested that some dark matter particles could be captured and destroyed in the Earth's core. This led to the release of energy, increased volcanic activity, and the creation of the "pulse of the Earth" that Melott had previously associated with extinctions.

Well, maybe so. But some scientists consider these ideas too dubious, and it is unlikely that they would attract much attention if they were put forward by someone else who was not as famous as Randall, and she is almost a superstar in the field of cosmology.

“You have to invent new physics to make this mechanism work,” says Melott.

"This argument seems far-fetched to me," agrees Beach.

But he adds that while it is not yet clear whether our galaxy actually has a dark matter disk, “we know so little about the distribution and composition of dark matter in the galactic disk and halo that any assumption within our current uncertainty is entirely possible.” So far, this is an interesting but dubious idea. Should I trust her?

All of the individual stories we have discussed are unsubstantiated, and many of them are controversial. But take a step back - and you will have no doubt that one way or another life on Earth is connected and dependent on cosmic forces. The difficulty lies in figuring out which cosmic phenomena played a role in a single case. These factors have stretched over such vast time scales that it is not even worth worrying about the impending threat to our survival in this vein. In the foreseeable future, our planet is not threatened by any catastrophic meteorite, although it is certainly worth watching.

But no one says that human civilization is completely protected from cosmic threats.

Melott says our biggest fear is solar flares: violent flares from the sun that bombard the planet with particles and radiation. The electromagnetic pulse they produce can paralyze telecommunications.

One such event in 1859 wreaked havoc on the early telegraph networks, shocking several operators and causing fires. Today, with our gigantic communications network, the consequences will be devastating. We narrowly escaped this fate in 2012 when a solar superstorm passed us, but there was a big one in 1989 that disrupted the Canadian power grid.

If an event like this can bring civilization to its knees, it could also leave an imprint on the evolutionary record, because, ironically, it will stop the latest mass extinction that is happening now due to our fault.

Global warming, asteroids, ozone holes - our planet is constantly under threat. What cataclysms will occur on Earth in the future and how will it die? Let's turn to the experts.

Apophis 99942 (2029)

The current headache for astronomers is the asteroid Apophis 99942, which today poses the greatest danger to the Earth. An unexpected guest, according to NASA researchers, the planet should be expected as early as 2029. The weight of the asteroid is 46 million tons, and the diameter is approximately half a kilometer. According to NASA forecasts, if this "baby" collides with our planet, it will cause a catastrophe, in comparison with which, the cataclysms that destroyed the dinosaurs will seem like a mere trifle.
According to 2009 data, the threat of catastrophe is 1 chance in 250 thousand. No reason to panic? You are mistaken, such a figure by cosmic standards is quite a significant indicator. In addition, according to William Eidor, a member of the NASA task force, this is the first time the authorities have shown interest in asteroids.

Water world (year 3000)

If mankind does not get it from the impending cosmic threat, then civilization will be destroyed by the well-known global warming. True, “destroy” is a strong word. It's just that we will live in a "water world", just like in an old Hollywood movie by Kevin Coster. According to scientists, in a thousand years the temperature could rise by 15 degrees Celsius, and sea levels could rise by more than 11 meters. At the same time, the inhabitants of the ocean will also have a hard time - the level of acidity in the water will increase, which will lead to the mass extinction of species.
Fortunately, according to Tim Lenton, lead researcher on the effects of global warming, the dire predictions can still be avoided. But for this, humanity will urgently have to reduce the amount of carbon dioxide emissions and moderate its greed in the use of resources.

Gamma radiation (600 million years)

And yet there are such cataclysms that a person cannot avoid. True, fortunately, such a catastrophe will not happen soon, but after 600 million years. The fact is that the Earth will have to face an unprecedentedly powerful flow of gamma rays, which will be thrown out by the Sun. This will create huge ozone holes, or rather destroy a good half of the Earth's ozone layer. The consequences are obvious - the transformation of our planet into a desert and the mass extinction of all living organisms. For example, one of the largest extinctions in the history of the planet - the Ordovician-Silurian extinction, which occurred 450 million years ago, according to one version, was the result of a burst of gamma radiation from a supernova located six thousand light-years from Earth.

New Venus (1 billion - 3.5 billion years)

The planet will not have time to recover from the next "sunstroke", as the star will bring her a new surprise. According to scientists, in about 1 billion years, the sun will begin its transformation into a red giant and all life on Earth will gradually be “burned out”. After some time, the Earth will turn into a second Venus, where the temperature has reached the boiling point of toxic metals, turning the entire planet into a poisonous wasteland. Scientists made this conclusion on the basis of observations of dying planets (KOI 55.01 and KOI 55.02) as part of the distant red giant KIC 05807616. By the way, salvation for humanity, if it still exists, can be Mars, which will be in the habitable zone.

Storms, earthquakes, volcanic eruptions - earthly cataclysms cost nothing to destroy human civilization. But even the most formidable elements will sink when a cosmic catastrophe enters the scene, capable of blowing up planets and extinguishing stars - the main threat to the Earth. Today we will show what the Universe is capable of in anger.

The dance of the galaxies will spin the Sun and throw it into the abyss

Let's start with the biggest disaster - the collision of galaxies. After some 3-4 billion years, it will crash into our Milky Way and swallow it up, turning into a huge egg-shaped sea of ​​​​stars. During this period, the Earth's night sky will break the record for the number of stars - there will be three to four times more stars. Do you know, ?

The collision itself does not threaten us - if the stars were the size of a table tennis ball, then the distance between them in the galaxy would be 3 kilometers. The biggest problem is the weakest, but at the same time the most powerful force in the Universe - gravity.

The mutual attraction of the stars in the merging Andromeda and the Milky Way will protect the Sun from destruction. If two stars approach each other, their gravity accelerates them and creates a common center of mass - they will circle around it, like balls around the edges of a tape measure. The same thing will happen with galaxies - before connecting together, their cores will “dance” next to each other.

What does it look like? Watch the video below:

Fear and loathing in the cosmic abyss

These dances will bring the most trouble. A star on the outskirts like the Sun will be able to accelerate to hundreds and even thousands of kilometers per second, which will break through the attraction of the galactic center - and our luminary will fly away into intergalactic space.

The Earth and other planets will remain together with the Sun - most likely, nothing will change in their orbits. True, the Milky Way, which pleases us on summer nights, will slowly move away, and the usual stars in the sky will be replaced by the light of lonely galaxies.

But you might not be lucky. In galaxies, in addition to stars, there are also whole clouds of interstellar dust and gas. The sun, once in such a cloud, begins to “eat” it and gain mass, therefore, the brightness and activity of the star will increase, irregular strong flares will appear - a real cosmic catastrophe for any planet.

Online galaxy collision simulator

To simulate a collision, left-click on a black area and drag the cursor slightly while holding the button towards the white galaxy. So you will create a second galaxy and set its speed. To reset the simulation, click reset at the bottom.

In addition, collisions with clouds of hydrogen and helium are unlikely to benefit the Earth itself. If you are not lucky enough to be in a massive cluster, you can find yourself inside the Sun itself. And about such things as life on the surface, water and familiar atmosphere can be safely forgotten.

Another Andromeda galaxy can simply “squeeze out” the Sun and include it in its composition. Now we live in a calm region of the Milky Way, where there are few supernovae, gas flows and other troubled neighbors. But no one knows where Andromeda will “populate” us - you can even fall into, full of energy of the most outlandish objects in the galaxy. The earth cannot survive there.

Should I be afraid and pack my bags to another galaxy?

There is one old Russian joke. Two old women walk past the planetarium and hear the guide say:

So, the Sun will go out in 5 billion years.
In a panic, one of the old women runs up to the guide:
- After how much, how long will it go out?
“In five billion years, grandma.
— Uf-f-f! Thank God! And it seemed to me that after five million.

The same applies to the collision of galaxies - it is unlikely that humanity will be able to survive until the moment when Andromeda begins to swallow the Milky Way. There will be little chance even if people try very hard. Already in a billion years, the Earth will become too hot for life to exist somewhere other than the poles, and after 2-3 there will be no water left on it, as on.

So you should only be afraid of the catastrophe below - it is much more dangerous and sudden.

Space disaster: supernova explosion

When the Sun runs out of its supply of stellar hydrogen fuel, its upper layers will be blown into the surrounding space, and only a small hot core, a white dwarf, will remain of it. But the Sun is a yellow dwarf, an unremarkable star. And big stars, 8 times more massive than our luminary, leave the cosmic scene beautifully. They explode, carrying small particles and radiation hundreds of light-years away.

As in the case of collisions of galaxies, gravity has a hand here. It compresses aged massive stars to such an extent that all their matter detonates. An interesting fact is that if a star is twenty times larger than the Sun, it turns into. And before that, she also explodes.

However, it is not necessary to be large and massive in order to one day shine in a supernova. The sun is a single star, but there are many star systems where the luminaries revolve around each other. Brother stars often age at different rates, and it may turn out that the “older” luminary burns out to a white dwarf, while the younger one is still in its prime. This is where the trouble begins.

When the "younger" star ages, it will begin to turn into a red giant - its shell will expand, and the temperature will decrease. This is what the old white dwarf will take advantage of - since there are no longer nuclear processes in him, nothing prevents him, like a vampire, from “sucking out” the outer layers of his brother. Moreover, it sucks them out so much that it breaks the gravitational limit of its own mass. Therefore, a supernova explodes like a big star.

Supernovae are the blacksmiths of the Universe, because it is the force of their flashes and compression that generates elements heavier than iron, like gold and uranium (according to another theory, they arise in neutron stars, but their appearance is impossible without a supernova). It is also believed that the outbreak of a star in the neighborhood of the Sun helped to form, including our Earth. Let's thank her for that.

Don't Rush to Love Supernovas

Yes, starbursts can be very useful - after all, supernovae are a natural part of the life cycle of stars. But for the Earth, they will not end in anything good. The most vulnerable part of the planet for supernovae is. Nitrogen, from which it mainly consists in the air, under the influence of supernova particles will begin to combine with ozone

And without the ozone layer, all life on Earth would become vulnerable to ultraviolet radiation. Remember that ultraviolet quartz lamps cannot be looked at? Now imagine that the whole sky has turned into one huge blue lamp that burns out all life. Marine plankton, which produce most of the oxygen in the atmosphere, will be especially bad.

Is the threat to Earth real?

What is the probability that a supernova will hit us? Look at the following photo:

These are the remains of a supernova that has already illuminated its own. It was so bright that in 1054 it could be seen as a very bright star even during the day - and this despite the fact that the supernova and the Earth are separated by six and a half thousand light years!

The diameter of the nebula is 11 . By comparison, our solar system is 2 light years from edge to edge, and 4 light years to our closest star, Proxima Centauri. There are at least 14 stars within 11 light-years around the Sun - each of them can explode. And the “combat” radius of a supernova is 26 light years. Such an event happens no more than 1 time in 100 million years, which is very common on a cosmic scale.

Gamma-ray burst - if the Sun became a thermonuclear bomb

There is another cosmic catastrophe, much more dangerous than hundreds of supernovae at the same time - a burst of gamma radiation. This is the most dangerous type of radiation that penetrates through any protection - if you climb into a deep basement from metal concrete, the exposure will decrease by 1000 times, but will not disappear completely. And any suits are completely unable to save a person: gamma rays weaken only two times, passing through a centimeter-thick sheet of lead. But a lead suit is an unbearable burden, dozens of times heavier than knightly armor.

However, even during the explosion of a nuclear power plant, the energy of gamma rays is small - there is not such a mass of matter to feed them. But such masses exist in space. These are supernovae of very heavy stars (like the Wolf-Rayet stars we wrote about), as well as the merger of neutron stars or black holes - recently such an event was recorded by gravitational waves. The strength of a gamma-ray flash of such cataclysms can reach 10 54 ergs that are emitted over a period of milliseconds to an hour.

Unit of measure - star explosion

10 54 erg - is it a lot? If the entire mass of the Sun became a thermonuclear charge and exploded, the energy of the explosion would be 3 × 10 51 erg - as in a weak gamma-ray flash. But if such an event occurs at a distance of 10 light years, the threat to the Earth will not be illusory - the effect would be like that of a nuclear bomb explosion on every conventional hectare of the sky! This would destroy life on one hemisphere instantly, and on the other in a matter of hours. Distance will not greatly reduce the threat: even if gamma radiation breaks out at the other end of the galaxy, an atomic bomb will reach our planet for 10 km 2 .

A nuclear explosion is not the worst thing that can happen

About 10 thousand gamma-ray bursts are recorded annually - they are visible at distances of billions of years, from galaxies on another. Within a single galaxy, a burst occurs approximately once every one million years. A logical question arises -

Why are we still alive?

The mechanism of the formation of a gamma-ray burst saves the Earth. Scientists call the energy of a supernova explosion "dirty" because it involves billions of tons of particles that scatter in all directions. A “pure” gamma-ray burst is a release of only one energy. It occurs in the form of concentrated rays extending from the poles of an object, star or black hole.

Remember the stars in the analogy with table tennis balls that are 3 kilometers apart? Now let's imagine that a laser pointer is screwed to one of the balls, shining in an arbitrary direction. What is the chance that the laser will hit another ball? Very, very small.

But do not relax. Scientists believe that gamma-ray bursts have already reached the Earth once - in the past they could cause one of the mass extinctions. To know for sure whether the radiation will reach us or not, it will be possible only in practice. However, it will be too late to build bunkers then.

Finally

Today we walked only through the most global space disasters. But there are many other threats to Earth, such as:

• Asteroid or comet impact (we wrote about where you can learn about the consequences of recent falls)
• The transformation of the Sun into a red giant.
• Flash on the Sun (they can be).
• Migration of the giant planets in the solar system.
• Stop rotation.

How to protect yourself and prevent tragedy? Follow science and space news and explore the universe with a reliable guide. And if something is unclear, or you want to know more - write in the chat, comments and go to