The consequences of meteorites of various diameters falling to the ground. A meteorite is flying to Earth: can it be prevented? Leonid meteor shower

Incredible news has long been spread all over the world - a huge celestial body is approaching our planet. In 2018, the asteroid will approach a record close quarters to Earth. So some scientists suggest that a collision is possible.

Of course, we want to believe in the best and hope that trouble will bypass us and all astronomical calculations will turn out to be false. However, it is better to analyze in advance the disaster that is approaching. Thanks to this, we can be prepared for any outcome that comes in the future.

Terrible asteroid

The Phaeton asteroid was discovered a long time ago, namely in 1983. At that time, it had already attracted the attention of researchers with its scale and original orbit. Astronomers have always been looking for attempts to properly understand this inhabitant of space. So they tried to accurately calculate its trajectory around the Sun. Scientists were also able to unravel the period of its rotation, and also understand its basic thermophysical characteristics.

Phaeton today belongs to the Apollo group. This celestial body moves around the Sun, so each time it approaches maximum distance, which is not inherent in objects of this type, namely 0.14 astronomical units. This is equal to about 21 million kilometers. Astronomers have suggested that the asteroid should be called the main celestial body of the Geminid meteor shower. It can be clearly seen in the middle of winter from our planet.

I must also say that this space object looks more like a comet space orbit, rather than an asteroid. Its trajectory around the Sun resembles a highly elongated ellipse. Also, during its continuous movement, Phaeton crosses the orbits of 4 planets terrestrial group. All this data gives astronomers a lot to think about, and also confirms their guesses regarding the nature of the asteroid. Scientists believe that it is the silicate core of a comet that lost its icy shell during its flight around the Sun.

In order to accurately determine the size and shape of a celestial body, it is necessary to collect photographs taken from different angles. As a rule, these photos can only be obtained after several decades. But astronomer Josef Hanus was able to use 55 photographs of the asteroid with his team. They were made between 1994 and 2015. Astronomers were also able to obtain 29 light curves using ultra-modern telescopes located around the world.

Hanus said that all this data helped to study in detail the shape and exact dimensions - 5.1 km, as well as the rotation period - 3.6 hours.

What danger threatens us?

In 2018, on October 12, the inhabitants of the planet will meet with a celestial body, the size of which is much larger than the Chelyabinsk meteorite. Scientists have been trying to predict the exact flight path of Phaeton for a couple of years in a row. After all, no one wants to future meeting still happened. Nowadays, it is impossible to say with certainty whether there will be a meeting or not. Only one thing is clear - the cosmic body will approach our planet at a distance of about 10 million kilometers. But then you just have to guess about the consequences of the approach. For now, scientists continue to monitor the object and find out its composition. This way, astronomers will be able to get closer to solving its connection with the Geminid meteor shower.

The largest meteorites that fell to Earth

The Goba meteorite is considered the largest. It fell in Namibia before historical times. The block lay underground for a very long time and was only found in 1920. It was found that when it fell, the cosmic body weighed 90 tons. But due to its long stay underground, as well as during research operations, the mass of the meteorite decreased to 60 tons. Most tourists today want to appropriate at least a small part of the celestial body.

The entire Astrakhan province in 1922 was able to observe the fall of a large fireball. It was accompanied by a deafening roar. As soon as it sounded sudden explosion, a rain of stones immediately fell from the sky. The day after the disaster, residents saw stone blocks of different sizes in their yard. The largest cobblestone weighed 284 kg. Today it can be found in the Fersman Museum in Moscow.

But in 1908, near the Podkamennaya River, the Tunguska happened powerful explosion force of 50 megatons. This power is observed only during an explosion hydrogen bomb. This phenomenon was followed by a strong blast wave. Because of it, large trees were uprooted. Residents of nearby villages had their windows fall out and many people and animals died. Locals they said that a few minutes before the fall they saw a bright ball in the sky that was rapidly descending to the ground. Remarkably, not a single group of researchers was able to find the remains Tunguska meteorite. But in the area of ​​the fall it was found a large number of silicate and magnesium balls. And in this area they could not form on their own. Therefore, they are attributed to cosmic origin.

The article talks about distinctive features asteroids and comets and events associated with their fall.

Science fiction films often depict a possible collision of the Earth with a large cosmic body. Special effects specialists spare no expense in creating apocalyptic pictures that describe the horrors of such a cosmic attack. But is the Earth really in danger of being torpedoed? uninvited guests from the Universe? If a collision occurs, what consequences should be expected? The two species that pose the greatest threat to our planet are: celestial bodies: asteroids and comets. Modern scientific equipment makes it possible to detect these objects in advance, at a distance of tens of millions of kilometers from the Earth. Astronomers are also able to calculate the trajectory of their movement and predict the distance of closest approach to us.

Asteroids - These are relatively small celestial bodies compared to planets. It is assumed that they are fragments of dead planets. Their sizes vary - from one centimeter to hundreds of kilometers in diameter. Small asteroids are not dangerous. Even if they reach the Earth, they will most likely burn up in the atmosphere or fall without any catastrophic consequences. Actually, this happens all the time - meteorites are just such small asteroids.

Asteroids with a diameter of a kilometer or more are dangerous. There are about 30,000 of them in the Solar System alone. The closest to us is Ceres, whose diameter is more than a thousand km.

The average speed of the asteroid is approximately 10 kilometers per second. Previously, large asteroids have already come close to the Earth. For example, in 1968, the very large asteroid Icarus flew 6.4 million km from us. Its collision with the Earth would be equivalent to the simultaneous explosion of 100 million tons of TNT. Several smaller asteroids flew at a short distance from us (105-170 thousand km) in 1991 and 1994. In ancient times, even before the advent of humanity, large asteroids also fell on Earth. According to one hypothesis, it was precisely this cataclysm that caused the mass death of dinosaurs. Scientists believe that a collision with a large celestial body occurs once every 500 thousand years.

What consequences could a large asteroid impact cause?

1. If its diameter is from one to several hundred kilometers, then all living things at a distance of hundreds and thousands of kilometers will be destroyed.

But life on Earth will survive. It’s a different matter if the space torpedo turns out to be a thousand kilometers or more in size. The fall of such a colossus into the ocean will lead to the appearance of a colossal crater and cause a gigantic tsunami that will go around the entire earth. But that’s not all - after the first wave there will be a second, no less destructive. The height of tsunami waves is expected to be 70 – 250 meters. The second wave will penetrate even lands far from the ocean and wash away all living things.

The fall of an asteroid onto a solid surface will raise huge clouds of dust and smoke into the air, which will long time will cover the sun. All living things will die from the lack of sunlight. Thus, the fall of a particularly large asteroid is likely to close the history of mankind.

However, an impact from a large asteroid is unlikely. It is more possible for a medium-sized asteroid to fall. The frequency of appearance of such heavenly guests is approximately once every 300 years.

2. Small and very small asteroids fall to Earth every day.

Currently, the list of asteroids potentially dangerous to the Earth includes 300 names. These are objects that can approach us at a relatively small distance by astronomical standards and at unfavorable conditions fall on earth's surface. Scientists have calculated that in 2086 the asteroid Hathor will approach dangerously close to a distance of 880 thousand km. This is a relatively small asteroid and an impact is unlikely.

Comets pose no less danger. They consist of a core and a tail. The core is usually 10 km or more in size, the tail is a million times longer. Passing through the tail of a comet is safe for the Earth due to the extreme rarefaction of its components. But the core is fraught with considerable dangers. The mass of the comet's nucleus can reach 10 trillion tons! The impact of such an object on the Earth is comparable to the explosion of several million atomic bombs at once! It is clear that all life forms will have very little chance of survival.

In 1994, debris from Comet Shoemaker-Levy fell onto Jupiter. Astronomers who observed the fall calculated that the resulting explosions from the collision were equivalent to the explosion of 60 million tons of TNT. Fortunately, we are not yet in danger of colliding with a large comet. The frequency of comets falling to Earth is hundreds of thousands of years. Three comets will pass close to Earth in the coming decades, but the distance will be more than nine million kilometers, which does not give much cause for alarm. In 1770, Comet Lexel came closest to Earth - at 2.3 million kilometers. And over the past two and a half millennia in written sources Only 20 close passages of comets have been recorded.

It would seem that there is no reason for alarm at all; comets are not going to visit us. But we must take into account that we're talking about only about comets known to us. Nobody knows what secrets the cosmos holds. Recently, astronomers discovered a comet cluster in the Kuiper belt and Oort cloud.

Last year, astronomers predicted more than once or twice that a celestial body would fall to Earth. In February, the American agency NASA predicted that a giant asteroid would fall to Earth. It was assumed that it would fall into the ocean and cause a supertsunami.

It was also indicated that this would happen near Great Britain, as a result of which the coastal residents were quite agitated. It was assumed, but no one can ever say anything about this for sure. Because a celestial body can either pass by our planet or still fall on it.

When will a meteorite fall on Earth in 2018: to date, assumptions about asteroids falling on Earth, fortunately, have not come true

In February it happened - a meteorite flew past and NASA’s assumptions, fortunately, did not come true.

Then they began to scare earthlings in March, then an asteroid hundreds of times larger than Chelyabinsk was supposed to land on Europe - that too. Then - in October, TC4 40 meters in diameter, the fall of which was supposed to leave a trace in the form of a huge crater - again lucky, it didn’t fall.

Astronomers usually have approximate data - both on the size and on the trajectory of the celestial body. After all, asteroids glow during flight, and therefore it is quite difficult to accurately determine their size. Moreover, once in the Earth’s atmosphere, the mass will be less due to the partial combustion of the space guest in it.

Fortunately, today, all celestial bodies that threatened Mother Earth either flew at a distance from her, or burned up in the layers of the atmosphere and turned into a safe meteor shower, which is a meteor shower and does not threaten earthlings in any way.

This was the case at the end of 2017, when astronomers were frightened by the approach of a meteorite threatening to fall on Nizhny Novgorod, Kazan or Samara. In February 2013, both the Chelyabinsk guest from space and the Yekaterinburg guest had approximately the same trajectory - the celestial bodies seem to like this route.

Fortunately, not all of them fall to Earth; most often, they pass tangentially to our planet and do not cause any harm. All celestial bodies migrating in the Universe are carefully observed in different points Earth astronomers and astrophysicists. After all, it is possible that the orbit of this or that meteorite will change for some reason and then it may well become a dangerous guest for our planet.

When a meteorite falls on Earth in 2018: scientists are closely monitoring the trajectory of the giant asteroid

This difficult issue remains relevant this year. Judging by the starfall calendar, 2018 is no safer than last year - the likelihood of meteorites falling to Earth remains just as high. But definitely something to say about the fall cosmic body scientists will be able only after it enters into earth's atmosphere, crumbling like a meteor shower. Until then, scientists can only guess which of the asteroids may be dangerous for earthlings.

For example, the meteorite that successfully missed the Earth at the end of 2017 is flying towards it again - it changed its orbit, colliding with another meteorite flying near the Moon. Now its flight path is oriented directly towards the Earth. But no one can say for sure how the journey of this space guest will end.

Here is a video confirming that a meteorite may fall to Earth in 2018:

When this may happen, time will tell. If it ends up in the Earth's atmosphere, it may burn up, perhaps it will disintegrate into meteor showers. Perhaps TV 145 also threatens the Earth - scientists are closely monitoring this giant asteroid, which has already flown quite close to the Earth.

4. Comets, meteors and minor planets

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4.1 The fall of a comet to Earth

Question: Do scientists foresee any comet falling to Earth? Answer: The fall of a comet onto the surface of the planet is a fairly rare astronomical phenomenon. Many scientists are inclined to think that the fall of the Tunguska meteorite (1908) was such a phenomenon. There are many facts in favor of this hypothesis. Anomalous mottled dawns that appeared a few days before the collision, white nights at unusual latitudes after the fall, the absence of solid meteorite matter, etc. Currently, this hypothesis about the nature of the Tunguska meteorite is considered generally accepted. The likelihood that such a phenomenon will happen again within a century is very low. And of those comets whose orbits are known, there are no candidates for a direct collision with the Earth. On the other hand, comets are objects that, on an astronomical scale, have a very short life. Perturbations of their orbits by other celestial bodies and tidal forces lead to the fact that the comet's trajectory can change, and it itself can break up into smaller bodies and form a meteor swarm in space. Since the comet's matter in a meteor swarm is "smeared" into a fairly extensive cloud, collisions with individual particles of such clouds occur quite regularly.

In 1994, an international conference on the problems of protecting the Earth from collisions with space objects was held in Snezhinsk. Those present came to the conclusion that humanity is capable of fighting the danger of space, protection against the fall of comets and asteroids is simple, the main thing is not to waste time.

A commission has been created to coordinate all work related to observations of space objects. Space radar and computer astronomical reconnaissance systems make it possible to detect dangerous objects hundreds of millions of kilometers from the Earth.

As of 1999, according to available data, comet Machhold-2 will come closest to Earth. The comet will approach Earth at a distance of 0.31 AU. (approximately 46 million km), the fact that the comet’s orbit is remote from the Earth indicates the impossibility of its fall to Earth.

Literature: R.V. Alimova and E.V. Dmitrieva "Anti-asteroid protection of the Earth" in the journal "Nature" 1995, N6, pp. 94-101.

4.4 Leonid meteor shower

Question: What is the Leonid meteor shower? Answer: Meteoric matter in interplanetary space is the most dynamic type of matter solar system. The smallest particles (radius less than approximately 0.5 microns) leave the Solar system under the influence of light pressure. Larger ones are decelerated as a result of the Robertson-Poynting effect, in spiral orbits they approach the Sun and fall onto it. The Robertson-Poynting effect is the deceleration of a body moving in a radiation field, arising due to the fact that in the coordinate system associated with this body, the light pressure force vector has a component directed against the velocity vector. A particle with a diameter of 10 microns and located in a circular orbit with a radius of 3 AU, as a result of this effect, falls on the Sun over a period of about 10 years. Since interplanetary meteoric matter is continuously removed from the Solar System as a result of processes associated with radiation pressure, it must be continuously renewed, which occurs as a result of the destruction of comets and asteroids.

With each approach to the Sun, the comet loses some of its mass in the form of gas and dust, ejected into the head and tail. At the same time, the heads of comets sometimes reach sizes exceeding the size of the Sun, and the tails sometimes have a length of more than 1 AU. As the spectrum of the comet shows, it contains both gas and dust components, the latter shines only by reflected light. sunlight. The same can be said for the brightest central part of the comet's head, which observers usually call the nucleus.

The comet suffers especially large losses when it forms anomalous tails consisting of large particles. The amount of gases remaining in the comet head clumps progressively decreases; Free dust quickly disperses in space. A periodic comet becomes weaker with each approach to the Sun; many of them “cannot withstand” more than two or three approaches to the Sun and cease to exist as comets. Others are known from a larger number of appearances, such as the 3.3-year comet Encke, discovered in 1786 and regularly observed to date with 47 appearances (eight were missed by observers).

Comet Halley, with a longer period of 76 years, has been observed since 466 BC. e. Over the past millennia, it has passed perihelion 32 times at a distance from the Sun of only 0.59 AU. Hard to say. whether it weakened during this time, but comet Encke weakened reliably over two centuries. Its absolute magnitude changed towards weakening by at least 2m. For many other comets this process is much faster.

There are frequent cases when comets are split into several parts, thereby demonstrating the low coherence of its substance. Classic example is Comet Biela.

When comets break apart, jets and ejections sometimes occur that can distort the comet's orbit. For example, the nucleus of Comet Encke rotates with a period estimated at approximately one day. When irradiated by the Sun, the core heats up, but the highest temperature does not occur at the subsolar point of the comet, but somewhat later, say, 10 - 15 in longitude towards the “evening”. Meanwhile, the emission of gas and dust is most abundant here, and during the ejection, reactive acceleration occurs in a direction that makes a noticeable angle with the radius vector of the comet, so that the reactive acceleration has a component perpendicular to the radius vector. This component increases or decreases the speed of the comet's orbital motion depending on whether the comet is spinning forward or backward. Along with acceleration, comets also experience slowdowns, although less frequently.

An example of the destruction of comets are two "scratching" comets observed by the SOLWIND satellite in close proximity from the Sun using a kind of coronagraph - in the shadow of an artificial disk, extended many meters ahead of the device and creating an imitation solar eclipse in the absence of atmospheric interference. In January and July 1981, comets were observed at distances from the Sun slightly greater than its radius, and even at solar corona did not cease to exist. It is safe to say that the entire dust component of these comets evaporated in the solar corona, but larger bodies that entered the comet’s nucleus (rocky blocks) “survived” the extremely high temperature during several hours of being in the corona and escaped along the original orbit, moving away from The sun is like a cluster of small solids and already invisible.

If this orbit intersects the Earth’s orbit, then every year, when the Earth hits the intersection point, meteor showers are observed, intensifying as the Earth and the remnants of the comet approach this point at the same time. If no enhancements are observed, it means that the comet’s matter has more or less evenly scattered throughout its orbit - the comet has completely ceased to exist as a celestial body.

Thus, disintegrating over time, the comet gives rise to a meteor shower moving along its orbit, from which we can conclude that the comet’s nucleus is not a single solid body, even of asteroid size, but a collection of individual bodies, the size of which defies precise definition. This aggregate, at a great distance from the Sun, consists of an unstable displacement of blocks, stones, grains of sand, dust particles, weakly connected with each other, but still forming for the time being a single whole, in which the binding substance is ice from all kinds of simple compounds of hydrogen and oxygen , carbon and nitrogen, which easily evaporate when the comet approaches the Sun. Then all the blocks and stones included in the ice with a diameter from several meters to centimeters and millimeters are exposed and, in turn, release adsorbed gases and supply dust. They can form a swarm of independent boulders and stones.

The frequency of meteors and their distribution across the sky are not always uniform. Meteor showers are systematically observed, the meteors of which appear in approximately the same area of ​​the sky over a certain period of time (several nights). If their tracks are continued back, they will intersect near one point, called the radiant of the meteor shower. Many meteor showers are periodic, repeating year after year, and are named after the constellations in which their radiants lie. Thus, the meteor shower, observed annually from approximately July 20 to August 20, is called the Perseids, since its radiant lies in the constellation Perseus. The Lyrid (mid-April) and Leonid (mid-November) meteor showers respectively get their name from the constellations Lyra and Leo.

Meteor shower activity in different years different. There are years in which the number of meteors belonging to the stream is very small, and in other years (repeating, as a rule, with certain period) so abundantly that the phenomenon itself was called star rain. The changing activity of meteor showers is explained by the fact that meteor particles in the streams are unevenly distributed along an elliptical orbit intersecting the earth's.

Three meteor showers - the Leonids, Andromedids and Draconids - showed very sharp bursts of activity in historical times, and in the case of the Andromedids this was directly related to the destruction of the Vistula comet, which in 1845. bifurcated and on its next appearance, in 1852, two faint comets were visible, separated by a distance of over 1.5 million km. Comet Biela was never seen again. But in 1872 and 1885, when the Earth crossed the orbit of Comet Vistula, and the comet itself, if it still existed, would be close to the crossing point, magnificent showers of slow meteors were observed (they overtook the Earth at a speed of 19 km / s) with an hourly their number reached 7500. In 1892 and 1899. The Andromedid flows intensified again, but only slightly. A subsequent outbreak of Andromedid activity was observed five years later, in 1904, while the orbital period of Comet Vistula was 6.6 years. This means that the meteor cluster existed far ahead of the " former comet"After 1940, Andromedid activity revived, but to a weak extent.

Currently, comet Giacobini-Zinner and the associated Draconid meteor shower successfully coexist. Comet 1900 III was discovered by Giacobini in 1900 shortly after its close approach to Jupiter. After another approach to Jupiter, in 1910, it was rediscovered in 1913 and was subsequently observed several times with an orbital period of 6.6 years. The node of the comet's orbit is now located at a distance of only 0.001 AU. from earth's orbit. On October 9, 1933, the Earth passed this point 80 days later than the comet crossed it. On this night there was also a magnificent shower of meteors with a radiant in Draco, with an hourly number of up to 6000 of them. 13 years later, on the night of October 9-10, 1946, an equally, if not more intense meteor shower was observed for 5-6 hours , while the Earth crossed the comet's orbit 15 days after the comet passed this place. In 1952, the Earth passed the point of convergence 195 days before the comet and again a small meteor shower was observed (hourly number 200), and in 1959 the Draconids were practically not observed, although the Earth was ahead of the comet at the place of greatest convergence of orbits by only three weeks. Thus, a meteor swarm formed behind Comet Giacobini-Zinner, but the comet itself suffered little from this: even in 1959 it was quite bright; On October 8, 1985, the Draconid shower again showed itself in full force - the hourly number of meteors according to radio observations reached one to three thousand.

The disintegration of comets and the formation of meteors, which are then distributed throughout the entire orbit or a significant part of it, occurs in such a way that meteoroids leave the cometary nucleus at moderate speeds. It was calculated, for example, that to explain those observed in 1933 and 1946. Draconid rains are enough for meteor particles to be ejected from the comet's nucleus at speeds of the order of 14-20 m/s. These particles are located quite precisely in the plane of the comet's orbit, otherwise the duration of the meteor shower would be much longer. An ejection speed of 10 m/s is enough for meteor particles to stretch out in 160 years in a small orbit, like the Geminids, and in 1100 years in a large orbit, such as Halley's Comet.

Of course, a meteor swarm that exists separately from a comet is subject to different planetary disturbances than the comet itself, and due to the lower accuracy of the meteor orbit, it is difficult to take the disturbances into account. That is why, in a completely unexpected way, individual meteor showers and concentrations in them either approach or move away from the Earth. Such, for example, is the unfulfilled Leonid rain in 1899, which did not take place, contrary to expectations: it was supposed to be as effective as in 1866, 1833 and 1799. This flow manifested itself again as rain in 1966.

The northern hemisphere began to change its climate to a hotter one 13 thousand years ago. When glacial period was coming to an end, the ice was melting and the spreading meadows were turning green. The warming was so rapid that the climate sometimes changed over decades, or even years.

But because of one thing unexpected event sudden changes occurred, expressed by a sharp drop in temperature. Then the Earth, almost approaching modern climatic conditions, returned to its former cold for another thousand years. And only after this time the climate became similar to the modern one.

What influenced the earth's climate

This cooling was called the Younger or Younger Dryas (after the dryad flower). However, the reasons for its occurrence were unclear until recently. New research is poised to shed light on this mystery. Scientists are confident that they have found evidence that the Earth was subject to numerous comet impacts, which at that time caused large-scale forest fires.

Most likely, one huge comet, split into parts, fell on our planet in the form of fragments. The fires caused by them were so strong that the ash and smoke entering the atmosphere prevented the passage of sun rays. As a result, this led to changes in ocean currents, destruction wildlife and, ultimately, the return of glaciation of the planet.

Consideration of the hypothesis

For a long time, many people treated the Younger Dryas with doubt, expressing their skepticism. Some didn't believe in external influence during the last stage of glaciation, followed by warming. This hypothesis was put forward only in 2007, and it talked about the impact of comet impacts that hit the Earth 12,800 years ago, which led to the Younger Dryas.

Previously it was believed that a circulation disorder led to the cold snap Atlantic waters north due to a sharp increase in volumes fresh water, released from glaciers as a result of their melting under the influence of warming.

Evidence found

Particles from comets were collected as evidence. These include tiny particles of the substance discovered in Pennsylvania, and traces of platinum in Greenland glaciers that survived an ancient comet collision. And in 2012, particles of the comet in the form of diamonds and impact spherules were discovered at the bottom of a Mexican lake.

A clue to such a hypothesis was also found on the walls of a temple complex in Turkey. Using the drawings, it was possible to study the position of celestial bodies, which indicated the fall of a comet.

The most most of A meteorite fell in what is now Canada. It was there that rare particles of osmium and iridium were found.

Evidence of large-scale fires ancient period scientists searched all over the world.
Thus, the researchers were able to prove that at that time terrible fires really raged, covering vast areas of forests. They were much larger than those that occurred during the time of the dinosaurs.

According to scientists, new facts can help in studying the history of life on Earth in those ancient times. They can explain the extinction of numerous animals, as well as the changes in human culture that occurred then.