Near-Earth asteroids. Asteroids and us Average orbital speed

Near-Earth asteroids ( Near-Earth asteroids) are asteroids with perihelion distances less than or equal to 1.3 AU. e.. Those of them that in the foreseeable future can approach the Earth at a distance less than or equal to 0.05 AU. e. (7.5 million km), and have an absolute magnitude of no weaker than 22m, and are considered potentially dangerous objects.

There are a huge number of comets and asteroids moving around the Solar System. Their bulk (more than 98%) is concentrated in the main asteroid belt (located between the orbits of Mars and Jupiter), the Kuiper belt and the Oort cloud (the existence of the latter is so far confirmed only by indirect evidence). Periodically, some objects in these regions, as a result of collisions with neighbors and/or under the influence of gravity of larger objects, leave their usual orbits and can be directed, including towards the Earth.

There are also many asteroids orbiting the Sun closer to the main belt. Those of them that approach the Earth, depending on the orbital parameters, are classified into one of the following four groups (traditionally called by the name of the first open representative):

Cupids(in honor of the asteroid (1221) Amur) - asteroids whose entire orbits lie further from the Sun than the Earth's aphelion. In total, at the moment (March 2013) the presence of 3653 asteroids of this group is known, of which 571 have been assigned serial numbers, and sixty-five have their own names. Cupids, like other representatives of near-Earth asteroids, are relatively small in size - only four cupids are known with a diameter of more than 10 km.

Apollos(after the asteroid (1862) Apollo) - asteroids whose perihelion is closer to the Sun than the Earth's aphelion, but the semimajor axis of their orbit is greater than the Earth's. Thus, in their movement they not only pass near the earth’s orbit, but cross it (from the outside). In total, at the moment (March 2013) the presence of 5229 asteroids of this group is known, of which 731 have been assigned serial numbers, and sixty-three have their own names. This is much larger than that of their related asteroids from the Aten group. This is the most numerous type of near-Earth asteroid. Such a large difference in the number of asteroids is explained by the fact that most of the time they are beyond the Earth’s orbit and can be observed at night. Considering the small size of these bodies (the largest is only 8.48 km), it is much easier to detect them at night against a dark sky than asteroids of the Atira or Aten group, which appear above the horizon only shortly before dawn or immediately after sunset and are easily lost in its rays against the backdrop of a still bright sky.

Atons(in honor of the asteroid (2062) Aten) - asteroids whose aphelion is further from the Sun than the Earth's perihelion, but the semimajor axis of their orbit is less than the Earth's. They cross the earth's orbit from the inside. In total, at the moment (September 2012) the presence of 758 asteroids of this group is known, of which 118 are assigned serial numbers, and nine have their own names.

Atira(after asteroid (163693) Atira) - asteroids whose entire orbits lie closer to the Sun than Earth's perihelion. In total, as of October 2014, only 14 asteroids are known to exist whose orbits are inside the Earth’s orbit. Such a small number of asteroids in this group is explained primarily by the difficulties of detecting and observing these bodies, as well as by their small sizes. The fact is that since these bodies are located inside the earth’s orbit, for an earthly observer they never move away from the Sun at a significant angle and, therefore, are constantly lost in the rays of the star. Because of this, their observation is possible only at dusk, in a short period of time shortly before dawn or immediately after sunset in a bright sky, in which it becomes very difficult to distinguish any celestial objects. Moreover, the smaller the semi-major axis of the asteroid’s orbit, the smaller the angle it moves away from the Sun, the brighter the sky at the moment of its appearance above the horizon, and the more difficult the observation conditions. That is why there is still no data on asteroids moving inside the orbit of Venus or, especially, Mercury (volcanoids).

The closest approaches to Earth were small (with a diameter of one to several meters) asteroids 2008 TS26 - up to 6150 km on October 9, 2008, 2004 FU162 - up to 6535 km on March 31, 2004, 2009 VA - up to 14,000 km on November 6, 2009.

Some of the small asteroids (for example, the meter-long 2008 TC3) enter the Earth's atmosphere as meteoroids, like meteors.

A few interesting examples:

(433) Eros(ancient Greek Ἔρως) is a near-Earth asteroid from the Amur group (I), belonging to the light spectral class S. It was discovered on August 13, 1898 by the German astronomer Carl Witt at the Urania Observatory and named after Eros, the god of love and constant companion of Aphrodite , according to ancient Greek mythology. This is the first discovered near-Earth asteroid.

It is interesting primarily because it became the first asteroid to have an artificial satellite, which on February 14, 2000 was the NEAR Shoemaker spacecraft, which a little later made the first landing on an asteroid in the history of space exploration.

Rotation of the asteroid Eros. Taken on February 14, 2001 from low orbit by the NEAR Shoemaker spacecraft:

Asteroid Eros crosses the orbit of Mars and approaches Earth. In 1996, the results of calculations of the dynamic evolution of the orbit of Eros over 2 million years were published. It is revealed that Eros is in orbital resonance with Mars. Orbital resonance with Mars can shift the orbits of Mars-crossing asteroids, such as Eros, so that they cross Earth's orbit. As part of the study, of the 8 initial orbits similar to the orbit of Eros, 3 evolved so that they began to intersect the Earth's orbit within the specified 2 million years. One of these orbits results in a collision with Earth after 1.14 million years. Although according to these calculations there is no significant danger of Eros colliding with the Earth in the next 105 years or so, such a collision is likely in the distant future.

Animation of rotation of the asteroid Eros

Eros is a relatively large asteroid, which ranks second in size among near-Earth asteroids, second only to asteroid (1036) Ganymede. It is believed that the impact potential of Eros, if it were to hit Earth, would be greater than that of the asteroid that created the Chicxulub crater, causing the K-T extinction event, which wiped out the dinosaurs on Earth.

As is known, gravity on the surface is inversely proportional to the distance to the center of mass of the body, which for Eros, as well as for most other asteroids, varies greatly due to their irregular shape: the larger the radius (for the same mass), the less gravity on its surface. Eros has a highly elongated shape, close to the shape of a peanut. Thus, at different points on the surface of Eros, the values of the acceleration of gravity can vary greatly in relation to each other. This is greatly facilitated by the forces of centripetal acceleration resulting from the rotation of the asteroid, which noticeably reduce the attraction to the surface at the extreme points of the asteroid, most distant from the center of mass.

The irregular shape of an asteroid also has a certain effect on the temperature regime of the surface, but the main factors influencing the temperature of the asteroid are still its distance from the Sun and the composition of the surface, on which the percentage of reflected and absorbed light depends. Thus, the temperature of the illuminated part of Eros can reach +100 °C at perihelion, and the unlit part can drop to −150 °C. Due to the elongated shape of Eros, it becomes possible for a small torque to appear under the influence of the YORP effect. However, due to the large size of the asteroid, the influence of the YORP effect is extremely insignificant and in the foreseeable future it is unlikely to lead to any noticeable change in the rotation of the asteroid. The density of the surface rocks of Eros is quite high for an asteroid, amounting to about 2400 kg/m³, which corresponds to the density of the earth’s crust, allowing Eros to maintain its integrity despite its relatively rapid rotation (5 hours 16 minutes).

Crater on the surface of Eros, 5 km in diameter

An analysis of the distribution of large rocks on the surface of the asteroid (433) Eros allowed scientists to conclude that most of them were ejected from a crater formed about 1 billion years ago as a result of a large meteorite falling on Eros. Perhaps as a result of this collision, 40% of the surface of Eros is devoid of craters with a diameter of less than 0.5 km. It was initially thought that the rock fragments ejected from the crater during the collision simply filled the smaller craters, making them impossible to see now. Crater density analysis shows that areas of lower crater density are up to 9 km from the impact point. Some zones of reduced crater density were found on the opposite side of the asteroid, also within 9 km.

It is assumed that seismic shock waves generated at the moment of impact passed through the asteroid, destroying small craters and turning them into rubble.

Asteroids are already being considered as potential sources of resources. Based on data obtained from the NEAR Shoemaker spacecraft, American David Whitehouse made interesting calculations about the possible “cost” of this asteroid in the event of mining on it. So, it turned out that Eros contains a large amount of precious metals, with a total value of at least 20 trillion dollars. This allowed us to look at the asteroid from a different point of view.

In general, the composition of Eros is similar to the composition of stony meteorites falling to Earth. This means that it contains only 3% metals. But at the same time, this 3% of aluminum alone contains 20 billion tons. It also contains rare metals such as gold, zinc and platinum. The 2,900 km³ of Eros contains more aluminum, gold, silver, zinc and other non-ferrous metals than has been mined on Earth in the entire history of mankind. At the same time, Eros is far from the largest asteroid.

All these figures are still just guesses, but they show what great economic potential the resources of the solar system can have, despite their immensity.

Since Eros belongs to the Amur group, he periodically approaches the Earth at a fairly close distance. So, on January 31, 2012, Eros flew at a distance of approximately 0.179 AU. e. (26.7 million km) from the Earth, which corresponds to 70 distances from the Earth to the Moon, while its apparent brightness will reach +8.5m. But since its synodic period is 846 days and is one of the longest among all bodies in the Solar System, such encounters occur no more often than once every 2.3 years. And during the closest approaches, which happen even less frequently, approximately once every 81 years (the last one was in 1975, and the next one will be in 2056), the apparent brightness of the asteroid Eros will be almost +7.0m - this is more than the brightness Neptune, as well as any other main belt asteroid, with the exception of such large asteroids as (4) Vesta, (2) Pallas, (7) Iris.

Eccentricity - 0.22; Perihelion - 169.569 million km; Aphelion - 266.638 million km; Circulation period - 1.76 years; Inclination - 10.82°. Diameter -34.4×11.2×11.2×16.84 km.

View of the surface of Eros from one of its ends

The asteroid was discovered on the same evening of August 13, 1898, independently of each other, by two astronomers: Gustav Witt in Berlin and Auguste Charlois in Nice, but Witt was still recognized as the pioneer of the discovery. The asteroid was discovered by him by accident as a result of a two-hour exposure to the star Beta Aquarius while carrying out astrometric measurements of the position of another asteroid, (185) Evnica. In 1902, at the Arequipa Observatory, based on changes in the brightness of Eros, its period of rotation around its axis was determined.

As a large near-Earth asteroid, Eros played a significant role in the history of astronomy. First, during the opposition of 1900-1901, a program was launched among astronomers around the world to measure the parallax of this asteroid to determine the exact distance to the Sun. The results of this experiment were published in 1910 by British astronomer Arthur Robert Hinks from Cambridge. A similar program of research was carried out later during the 1930–1931 confrontation by English astronomer Harold Jones. The data obtained as a result of these measurements was considered final until 1968, when radar and dynamic methods for determining parallax appeared.

Secondly, it became the first asteroid to have an artificial satellite, NEAR Shoemaker (in 2000), and on which this spacecraft landed a year later.

By reaching Eros, NEAR Shoemaker was able to transmit a large amount of data about this asteroid that would have been impossible or very difficult to obtain by other means. This device transmitted more than a thousand images of the asteroid’s surface, and also measured its basic physical parameters. In particular, deviations during the flight of the device near the asteroid made it possible to estimate its gravity, and therefore its mass, as well as clarify its dimensions.

On March 3, 2000, American Gregory Nemitz declared Eros his private property, and after landing the NEAR Shoemaker spacecraft on Eros, he tried to obtain a rent from NASA for the use of the asteroid in the amount of $20 in court. However, the court rejected his claim.

Harry Harrison's novel Captive Universe (1969) takes place inside the asteroid Eros. People live in an artificial cavity at the center of the asteroid, and the asteroid itself is transformed into a generational spaceship flying towards the planetary system of Proxima Centauri.

In Card Orson Scott's story, Ender's Game is introduced as the Bugmen's former base for invading Earth.

In the television series "The Expanse" on Eros, like many others, there is a colony of prospectors. This colony was used as a biological weapons testing ground.

(1036) Ganymede(ancient Greek Γανυμήδης) is the largest near-Earth asteroid from the Amur group (III), which belongs to the dark spectral class S. It was discovered on October 23, 1924 by the German astronomer Walter Baade at the Hamburg Observatory and named after Ganymede, an ancient Greek youth, kidnapped by Zeus.

Thanks to its large size and regular approaches to the Earth, the orbit of Ganymede was established with a high degree of accuracy and the parameters of subsequent approaches were calculated. The closest of them will occur on October 13, 2024, when Ganymede will pass at a distance of 55.9641 million km (0.374097 AU) from Earth, while its apparent magnitude can reach 8.1m. It also regularly crosses the orbit of Mars and will pass just 4.290 million km (0.02868 AU) from that planet on December 16, 2176.

Eccentricity - 0.5341189; Perihelion - 185.608 million km; Aphelion - 611.197 million km; Orbital period - 4.346; Inclination - 26.69°; Diameter – about 33 km; Albedo - 0.2926.

Since the asteroid was discovered at the beginning of the 20th century, it has a rich history of astronomical observations. Its absolute magnitude was determined back in 1931 and was equal to 9.24m, which differed quite a bit from the results of modern observations (9.45m). The asteroid belongs to the light class S, which means it contains a large amount of iron and magnesium silicates, as well as various orthopyroxenes.

Radar observations of Ganymede carried out in 1998 using the Arecibo radio telescope made it possible to obtain images of the asteroid, based on which we can talk about the spherical shape of this body. Around the same time, observations were carried out to obtain light curves and polarization curves of the asteroid, but due to bad weather, these studies could not be carried out in full. However, the data obtained allowed us to conclude that there is a weak correlation between these curves depending on the angle of rotation of the asteroid. Since the degree of polarization depends on the roughness of the surface and the composition of the soil, this indicates the relative homogeneity of the asteroid’s surface, both in relief and in rock composition. Later observations of light curves, carried out in 2007, made it possible to determine the period of rotation of the asteroid around its axis, which is equal to 10.314 ± 0.004 hours.

(2102) Tantalum(Ancient Greek: Τάνταλος) is a near-Earth asteroid from the Apollo group, which belongs to the rare spectral class Q and is characterized by a rather elongated orbit, which is why during its movement around the Sun it crosses not only the orbit of the Earth, but also Mars. But the main feature of this asteroid is the extremely large inclination of the orbit to the ecliptic plane (over 64 degrees), which is a kind of record among all asteroids that have their own names.

It was discovered on December 27, 1975 by American astronomer Charles Koval at the Palomar Observatory and was named after the Greek mythology character Tantalus, king of Sipylus in Phrygia.

Treatment period: 1.5 years. Eccentricity - 0.30. Diameter - about 3 km.

(4179) Tautatis(Toutatis; transcriptions Toutatis and Toutatis are also found in the domestic scientific literature and in the media) is an asteroid from the Apollo group approaching the Earth, whose orbit is in resonances of 3:1 with Jupiter and 1:4 with the Earth.

Tautatis was first discovered on February 10, 1934 and subsequently lost. Then he was given the designation 1934 CT. The asteroid remained lost for several decades until it was rediscovered on January 4, 1989 by Christian Pollya. The asteroid was named after the Celtic god Teutates.

Due to the low inclination of its orbit (0.47°) and short orbital period (about 4 years), Tautatis often approaches the Earth, and the minimum possible approach distance (MOID with the Earth) at the moment is 0.006 AU. e. (2.3 times the distance to the Moon). The approach on September 29, 2004 was particularly close, when the asteroid passed at a distance of 0.0104 AU. e. from the Earth (4 radii of the lunar orbit), providing a good opportunity for observations - the maximum brightness of the asteroid was 8.9 magnitude.

The Tautatis rotation consists of two different periodic movements, as a result of which it appears chaotic; If you are on the surface of an asteroid, the Sun will appear to rise and set below the horizon in random places and at random times.

The Tautatis radiolocation using radio telescopes in Evpatoria and Effelsberg, carried out in 1992 under the direction of A.L. Zaitsev, was the first radiolocation of a minor planet outside the United States.

Radar studies have shown that Tautatis has an irregular shape and consists of two “lobes” measuring 4.6 km and 2.4 km, respectively. There is an assumption that Tautatis was formed from two separate bodies, which at some point “merged”, as a result of which the asteroid can be compared to a “pile of stones”.

Tautatis is in a 3:1 resonance with Jupiter and 1:4 with the Earth. As a result, gravitational disturbances lead to chaotic behavior of Tautatis’s orbit, which is why it is currently impossible to predict changes in its orbit more than 50 years in advance.

The close approach to Earth in 2004 was strong enough to raise questions about the possibility of a collision. However, the possibility of an asteroid colliding with the Earth is extremely low.

There is a possibility that Tautatis will be ejected beyond the solar system in a few tens or hundreds of years due to gravitational interactions with the planets.

The Chinese lunar probe Chang'e-2, placed after completing the main program at the Lagrange point L2 of the Earth-Moon system, was redirected on April 15, 2012 to study the asteroid (4179) Tautatis.

Chang'e-2 image of Tautatis

On December 13, 2012, Chang'e 2 flew past the asteroid (4179) Tautatis. At 08:30:09 UTC (12:30:09 Moscow time), the spacecraft and the celestial body were separated by 3.2 kilometers. Images of the asteroid's surface were obtained with a resolution of 10 meters.

Eccentricity - 0.62; Perihelion - 140.544 million km; Aphelion - 617.865 million km; Circulation period - 4.036 years; Inclination - 0.44715°; Albedo - 0.13.

(1566) Icarus(ancient Greek Ἴκαρος) is a small near-Earth asteroid from the Apollo group, which is characterized by an extremely elongated orbit. It was discovered on June 27, 1949 by German astronomer Walter Baade at the Palomar Observatory in the United States and named after Icarus, a character in ancient Greek mythology known for his unusual death.

The asteroid has a very high orbital eccentricity (almost 0.83), due to which, during its orbital movement, it significantly changes its distance from the Sun and intersects the orbits of all terrestrial planets. Thus, Icarus lives up to its name, penetrating at the perihelion of its orbit inside the orbit of Mercury and approaching the Sun at a distance of up to 28.5 million km. At the same time, its surface at such a distance from the Sun heats up to a temperature of over 600 °C. Perihelion - 27.924 million km; Aphelion - 294.597 million km; Inclination - 22.828°; Diameter - 1.0 km; Albedo - 0.51.

Between 1949 and 1968, Icarus came so close to Mercury that its gravitational field changed the orbit of the asteroid. In 1968, Australian astronomers carried out calculations according to which, as a result of Icarus’ approach to our planet that year, the asteroid could well have crashed to Earth in the Indian Ocean near the African coast. Fortunately, these calculations did not come true; the asteroid passed by at a distance of only 6.36 million km. However, if it did fall to Earth, the impact energy would be equivalent to 100 Mt of TNT.

The asteroid Icarus approaches Earth every 9, 19 and 38 years. The penultimate time the asteroid came close was in 1996 and flew at a distance of 15.1 million km. The last time was on June 16, 2015 - the asteroid flew at a distance of 8.1 million km from Earth. This time it could have fallen in the middle of the Atlantic Ocean between Europe and North America. Then one fifth of the world's population could die. The next time the asteroid will approach Earth at a comparable distance (6.5 million km from the planet) is June 14, 2090.

In the spring of 1967, a professor at the Massachusetts Institute of Technology assigned his students the task of drawing up a project for the destruction of this asteroid in the event of its imminent collision with the Earth, which became known as “Project Icarus.” The project was first reported in Time magazine in June 1967, and the best work was published in book form a year later. This work inspired Hollywood producers to create the disaster film Meteor.

In the Soviet science fiction film “The Sky is Calling” (1959), a Soviet rescue expedition with Americans on board makes an emergency landing on the Icarus asteroid. They are trying to help them from Earth.

American writer Arthur C. Clarke (1960), in his science fiction story “Summer on Icarus,” describes the conditions on an asteroid where, due to a malfunction of the spacecraft, astronaut Sherrard, a member of an expedition to explore the Sun, ended up.

(3200) Phaeton(lat. Phaethon) is a small near-Earth asteroid from the Apollo group, which belongs to the rare spectral class B. The asteroid is interesting due to its unusual extremely elongated orbit, due to which, in the process of its movement around the Sun, it intersects the orbits of all four terrestrial planets from Mercury to Mars . Interestingly, at the same time it comes quite close to the Sun, which is why it was named after the hero of the Greek myth about Phaeton, the son of the sun god Helios.

This asteroid is also special in that it was the first asteroid discovered in a photograph taken from a spacecraft. Simon F. Green and John C. Davis discovered it on October 11, 1983, in images from the IRAS infrared space satellite. Its discovery was announced the next day, October 14, after confirmation by optical observations by Charles T. Koval. The asteroid received the temporary designation 1983 TB.

It is classified as an Apollo asteroid because its semimajor axis is greater than Earth's and its perihelion is less than 1.017 AU. e. It may also be a member of the Pallas family.

Perihelion - 20.929 million km; Aphelion - 359.391 million km; Circulation period - 1.433 years; Inclination - 22.18°; Albedo - 0.1066.

The main feature of Phaeton is that it approaches the Sun closest to all other large asteroids of its group (the record belongs to 2006 HY51 (en:2006 HY51)) - at a distance more than 2 times less than the perihelion of the planet Mercury, while the speed of Phaeton is near The sun can reach almost 200 km/s (720,000 km/h). And due to the record high eccentricity, close to 0.9, Phaeton, in the process of its movement around the Sun, crosses the orbits of all four terrestrial planets.

Phaeton's orbit itself is more similar to the orbit of a comet than to the orbit of an asteroid. Studies in the infrared region of the spectrum have shown that its surface consists of hard rocks, and, despite high temperatures of ~1025 K, during the entire period of observations it has never been possible to record the appearance of a coma, a tail, or any other manifestations of cometary activity . Despite this, shortly after its discovery, Fred Whipple noted that the orbital elements of this asteroid practically coincide with the orbital parameters of the Geminids meteor shower. In other words, the asteroid may be the source of the Geminids meteor shower, whose maximum activity occurs in mid-December. Perhaps it represents a degenerate comet that has exhausted its entire supply of volatile compounds, or they were buried under a thick layer of dust.

The asteroid is a small body measuring 5.1 km. Since Phaeton is believed to be of cometary origin, it is classified as a spectral class B asteroid, with a very dark surface consisting primarily of anhydrous silicates and hydrated clay minerals. The same mixed asteroid-comet features were discovered in another object, designated 133P/Elst-Pizarro.

In the 21st century, several very close encounters of this asteroid with the Earth are expected at once: one has already happened on December 10, 2007, when the asteroid flew past our planet at a distance of 18.1 million km, the closest one happened in 2017, the next encounters will occur in 2050, 2060 and the closest is in 2093, December 14, when the expected distance between Earth and Phaeton will be only about 3 million km.

(2212) Hephaestus(lat. Hephaistos) is a near-Earth asteroid from the Apollo group, characterized by an extremely elongated orbit and, as a result, has become quite widely known. It was discovered on September 27, 1978 by Soviet astronomer Lyudmila Chernykh at the Crimean Astrophysical Observatory and named after the ancient Greek god of fire and blacksmithing, Hephaestus.

The very large eccentricity of the orbit causes significant fluctuations in the distance of Hephaestus to the Sun, due to which this asteroid not only crosses the orbits of all four terrestrial planets from Mercury to Mars, but also, crossing the entire asteroid belt, comes close to the orbit of Jupiter.

Eccentricity - 0.837; Perihelion - 52.591 million km; Aphelion - 594.265 million km; Inclination - 11.58°; Diameter - 5.7 km.

(163693) Atira(lat. Atira) - a small rapidly rotating near-Earth asteroid, leading the Atira group; the first discovered asteroid whose orbit is entirely within the Earth's orbit. It was discovered on February 11, 2003, as part of the LINEAR asteroid search project at the Socorro Observatory and is named after Atira, the earth mother goddess and evening star in Pawnee Indian mythology.

According to established tradition, a new group of near-Earth asteroids gets its name in honor of its first discovered representative. Therefore, the choice of name for this asteroid was taken especially seriously. Since the names of the asteroids of the three other groups of near-Earth asteroids (Atons, Amurs and Apollos) began with the letter “A”, it was decided that in this case the name of this asteroid should begin with the same letter. Since the observatory where the asteroid was discovered is located in the southwestern United States, it was decided to use the mythology of the Indians who lived in this area to choose the name. Thus, the asteroids included in this small but important group of near-Earth asteroids are now called Atira group asteroids.

Due to its elongated orbit (eccentricity 0.322), the asteroid at times appears closer to the Sun than Venus, and comes quite close to the orbit of Mercury, and its entire orbital journey takes just over 233 Earth days. With a diameter of 4.8 km, the Atira asteroid is the largest representative among all 17 bodies of this group known today. Perihelion - 75.147 million km. Aphelion - 146.577 million km. Inclination - 25.61°; Albedo - 0.10.

(99942) Apophis(lat. Apophis) is a near-Earth asteroid discovered in 2004 at the Kitt Peak Observatory in Arizona. Preliminary name 2004 MN4, received its proper name on July 19, 2005. This tiny asteroid, despite its size (only about 300 meters), can be called the most “promoted” by numerous mass media due to the panic around its possible collision with the Earth, for this reason it is the most famous in the community of near-Earth asteroids.

The asteroid is named after the ancient Egyptian god Apep (in ancient Greek pronunciation - Άποφις, Apophis) - a huge serpent, a destroyer who lives in the darkness of the underworld and tries to destroy the Sun (Ra) during its night transition. The choice of such a name is not accidental, since according to tradition, small planets are called by the names of Greek, Roman and Egyptian gods. The scientists who discovered the asteroid, D. Tolen and R. Tucker, allegedly named it after the negative character from the series “Stargate SG-1” Apophis, also taken from ancient Egyptian mythology.

The asteroid belongs to the aten group, and is approaching the Earth's orbit at a point approximately corresponding to April 13. Eccentricity - 0.19; Perihelion - 111.611 million km; Aphelion - 164.349 million km; Orbital period - 0.886; Inclination - 3.332°; Albedo - 0.23.

According to new data, Apophis will approach the Earth in 2029 at a distance of 38,400 km from the center of the Earth (according to other data: 36,830 km, 37,540 km, 37,617 km) from it. After radar observations, the possibility of a collision in 2029 was excluded, however, due to the inaccuracy of the initial data, there was a possibility of this object colliding with our planet in 2036 and subsequent years. Various researchers have estimated the mathematical probability of collision as 2.2 10−5 and 2.5 10−5. There was also a theoretical possibility of a collision in subsequent years, but it is significantly lower than the probability in 2036.

According to the Turin scale, the danger in 2004 was rated at 4 (a Guinness record), but remained at level 1 until August 2006, when it was lowered to 0.

In October 2009, positional observations of the asteroid were published, made at the Mauna Kea and Kitt Peak observatories on two-meter telescopes between June 2004 and January 2008. Some time later, taking into account new data, scientists at the Jet Propulsion Laboratory (a division of NASA) A recalculation of the trajectory of the celestial body was carried out, which made it possible to significantly reduce the level of the asteroid danger of Apophis. If previously it was assumed that the probability of an object colliding with the Earth was 1:45,000, now this figure has dropped to 1:250,000.

After the asteroid approached the Earth on January 9, 2013 to a distance of 14 million 460 thousand km (which is less than a tenth of the distance to the Sun), it turned out that the volume and mass of Apophis was 75% greater than previously thought.

New data about the asteroid Apophis was obtained using the Herschel space observatory. According to previous estimates, the diameter of Apophis was supposed to be 270 ± 60 meters. According to updated data, it is 325 ± 15 meters. A 20% increase in diameter gives a more than 70% increase in volume and (assuming homogeneity) mass of the celestial body. Apophis reflects only 23% of the light incident on its surface.

Location of possible impact sites for Apophis if he collided with Earth in 2036.

NASA's initial estimate for the TNT equivalent of an asteroid impact explosion was 1,480 megatons (Mt), which was later lowered to 880 and then to 506 Mt after clarification of the size. For comparison: the energy release during the fall of the Tunguska meteorite is estimated at 10-40 Mt; the explosion of the Krakatoa volcano in 1883 was equivalent to approximately 200 Mt; The explosion energy of the thermonuclear aircraft bomb AN602 (aka “Tsar Bomb”) at the Sukhoi Nos nuclear test site (73°51′ N 54°30′ E) on October 30, 1961, according to various sources, ranges from 57 to 58.6 megatons of TNT equivalent; The energy of the explosion of the “Baby” nuclear bomb over Hiroshima on August 6, 1945, according to various estimates, ranges from 13 to 18 kilotons.

The effect of the explosion could vary depending on the asteroid's composition and the location and angle of impact. In any case, the explosion would cause massive destruction over an area of thousands of square kilometers, but would not create long-term global effects like an “asteroid winter.”

It should be noted that due to the updated data on the size, which turned out to be slightly larger, the consequences of the impact could have been more destructive.

According to the proposals of scientists, in order to clarify the trajectory, composition and mass of the asteroid, it is necessary to send an automatic interplanetary station (AIS) to it, which will carry out the necessary research and install a radio beacon on it for precision measurement of changes in its coordinates in time, which will make it possible to more accurately calculate the orbital elements, gravitational orbital disturbances from other planets, and thus better predict the likelihood of a collision with the Earth.

In 2008, the American Planetary Society held an international competition of projects to send a small satellite to Apophis for trajectory measurements of the asteroid, in which 37 institute and other initiative teams from 20 countries took part.

One of the most exotic options suggested that Apophis should be wrapped in highly reflective film. The pressure of sunlight on the film will change the asteroid's orbit.

NASA has almost completely ruled out the possibility of Apophis colliding with Earth in 2036. This conclusion was made based on data collected by several observatories during the flyby of Apophis at a distance of 14.46 million kilometers from Earth on January 9, 2013.

Scientists also previously believed that after a close approach to the Earth in 2029, the orbit of Apophis may change, which will lead to an increased risk of its collision with our planet in 2036 during the next approach. Now this possibility is almost completely excluded.

In the computer game Rage, the asteroid Apophis crashes into Earth on April 13, 2029, killing 5 billion people within the first 24 hours. Before the disaster, top politicians, scientists and military leaders were placed in specially built cryo-arks. The arks are supposed to come to the surface with their stored human cargo when the damage caused by Apophis has passed.

(3552) Don Quixote(Spanish: Don Quijote) is a near-Earth asteroid from the Amur group (IV), belonging to a rather rare spectral class D. Due to its highly elongated orbit, due to its significant eccentricity, the asteroid immediately crosses both the orbit of Mars and the orbit of Jupiter, while , at its perihelion approaching quite close to the Earth’s orbit (up to a distance of 0.193 AU), which determines its belonging to the Amur group asteroids and allows it to be classified as a “near-Earth object.”

All this suggests that asteroid (3552) Don Quixote is actually a degenerate comet that has already exhausted its reserves of volatile substances and has turned into an ordinary block of stone. This asteroid has one of the longest periods of revolution around the Sun from the group of near-Earth asteroids - 8.678 years andis one of the darkest known asteroids, with an albedo of about3 %. .

Eccentricity - 0.71; Perihelion - 181.022 million km; Aphelion - 1.08248 billion km; Inclination - 30.96; Diameter - 19.0 km.

(3691) Trouble(lat. Maera) is a small near-Earth asteroid from the Amur group (II), which was discovered on March 29, 1982 by the Chilean astronomer L. E. González at the Cerro El Roble Observatory and named after the Benedictine monk who wrote the first works on the history of England, known as Bede the Venerable .

The asteroid is remarkable in that, with its size just over 4 kilometers, it has an extremely slow rotation period - more than 9 days. Unwieldy Trouble....

Eccentricity - 0.28; Perihelion - 189.982 million km; Aphelion - 340.886 million km: Orbital period - 2.363 years; Inclination - 20.35°

The other extreme, an asteroid 2008 H.J. - an unnamed near-Earth asteroid from the Apollo group.

The history of the discovery of asteroid 2008 HJ is interesting. It was discovered in April 2008 by amateur astronomer Richard Miles from Dorset (UK). He made the discovery without leaving home, thanks to the fact that he had remote access via the Internet to the Australian, fully automated Folkes telescope. The English educational project, in which R. Miles observed the starry sky, provides free of charge to schoolchildren, students and astronomy enthusiasts from the UK the opportunity to work on two large telescopes located in Australia and Hawaii.

From observations of periodic changes in the asteroid's brightness associated with its rotation, an English amateur found that 2008 HJ makes one revolution around its axis in less than a minute (according to his data, in 42.7 seconds, which is very close to the specified - 42.67 seconds) . Before the rotation speed of asteroid 2008 HJ was determined, the record holder was considered to be asteroid 2000 DO8 with a rotation period of 78 seconds. It is possible that other record holders of this kind will be discovered.

The dimensions of the asteroid are quite modest - only 12 by 24 meters. Less tennis court. But the weight of the 2008 HJ is about 5,000 tons. Despite the fact that 2008 HJ is included in the category of “near-Earth” asteroids, it did not approach our planet closer than a million kilometers and does not pose a danger. The closest the asteroid was to Earth was in April, when it rushed past at a speed of 162,000 km/h.Treatment period – 2 years; Inclination – 0.92.

Scales

There are several scales for assessing the danger of VET.

Turin scale

Asteroids (0 points) - consequences of a collision: they have no chance of meeting the Earth.
Asteroids (10 points) - consequences of a collision: the number of species inhabiting our planet should be reduced by orders of magnitude.

Judging by geological data (several hundred impact craters have been explored), collisions with large celestial bodies have happened more than once in the history of our planet. Some scientists explain the mass extinction of living organisms (about 250 million years ago) by the fall of one large meteorite. Another meteorite, according to the hypothesis of U. Alvarez, led to the extinction of dinosaurs.

Sources

The closest to Earth was a small asteroid 2004 FU 162 (diameter about 6 meters) - about 6500 km from Earth (March 2004).

Discovery history

Historically, the first of the asteroids with an orbit close to the Earth was discovered by Eros (Amur group). The largest asteroid in the Amur group is Ganymede (which should not be confused with the moon of Jupiter of the same name), its diameter is approximately 32 km (Eros has about 17 km).

Asteroid 2008 TC 3 - discovered 20 hours before it burned up in the atmosphere over Sudan on October 7, 2008.
Asteroid 2009 DD 45 - discovered on February 28, 2009 (three days before its closest approach to Earth) by astronomer Robert McNaught, who studied photographs taken using the Schmidt telescope at Siding Springs Observatory in Australia. The asteroid came closest to the Earth on March 2, 2009 (16:44 Moscow time, according to representatives of the Planetary Society - 13:44 GMT). Can be seen with the naked eye in the skies over the South Pacific Ocean. Dimensions - 20-50 (27-40) meters. Distance to Earth - 66 (72) thousand km. The spread of numbers is due to the fact that the diameter of asteroids is calculated based on their albedo - reflectivity. Since astronomers don't know exactly how much light is reflected by the surface of 2009 DD45, they rely on averages. Speed of movement - (at the moment of being at a minimum distance from the Earth - 20 km/s. In the event of a collision, the energy of the explosion would be equal to 1 megaton (one high-power nuclear bomb) in TNT equivalent. For comparison: the impact of the Tunguska meteorite (exploded in the atmosphere over Siberia 30 June 1908) 80 million trees were felled over an area of about 2000 square kilometers, which corresponds to an explosion of 3-4 megatons of TNT.

Difficulty in detection

Financial

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. However, NASA currently tracks mainly the largest space objects, those with a diameter of more than a kilometer (as of 2007, 769 known asteroids and comets whose diameter does not exceed 140 meters are not observed so closely).

Technical

Current state

In total, about 6,100 objects have been registered that pass at a distance of up to 1.3 astronomical units from the Earth.

As of April 2009, not a single PEO was observed in the Solar System (a list of slightly more than a thousand positions, where 90% are asteroids, 10% are comets, the distance from them to the Earth is less than 0.05 astronomical units), which could overcome the milestone zero points.

The danger that asteroids pose to the planet is not considered serious. According to modern estimates, collisions with such bodies (according to the most pessimistic forecasts) are unlikely to occur more often than once every hundred thousand years. If a celestial body of sufficient size is directed towards Earth to cause serious destruction, astronomers will be able to detect it.

Notes

Links

Zheleznov N. B. Asteroid-comet hazard: current state of the problem.
Finkelstein A., corresponding member RAS. Asteroids threaten the Earth. Science and Life, No. 10, 2007, pp. 70-73.
Earth's Impact Craters Database.
Near-Earth Asteroid Database (English).

Wikimedia Foundation. 2010.

The Earth can be threatened by objects that approach it at a distance of at least 8 million kilometers and are large enough not to collapse when entering the planet’s atmosphere. They pose a danger to our planet.

Until recently, the asteroid Apophis, discovered in 2004, was called the object with the highest probability of colliding with the Earth. Such a collision was considered possible in 2036. However, after Apophis passed by our planet in January 2013 at a distance of about 14 million km. NASA specialists have reduced the likelihood of a collision to a minimum. The chances, according to Don Yeomans, head of the Near-Earth Object Laboratory, are less than one in a million.
However, experts have calculated the approximate consequences of the fall of Apophis, whose diameter is about 300 meters and weighs about 27 million tons. So the energy released when a body collides with the Earth’s surface will be 1717 megatons. The strength of the earthquake within a radius of 10 kilometers from the crash site can reach 6.5 on the Richter scale, and the wind speed will be at least 790 m/s. In this case, even fortified objects will be destroyed.

Asteroid 2007 TU24 was discovered on October 11, 2007, and already on January 29, 2008 it flew near our planet at a distance of about 550 thousand km. Thanks to its extraordinary brightness - 12th magnitude - it could be seen even in medium-power telescopes. Such a close passage of a large celestial body from Earth is a rare occurrence. The next time an asteroid of the same size will approach our planet will only be in 2027.
TU24 is a massive celestial body comparable to the size of the University building on Vorobyovy Gory. According to astronomers, the asteroid is potentially dangerous because it crosses the Earth's orbit approximately once every three years. But, at least until 2170, according to experts, it does not threaten the Earth.

Space object 2012 DA14 or Duende belongs to the near-Earth asteroids. Its dimensions are relatively modest - a diameter of about 30 meters, a weight of approximately 40,000 tons. According to scientists, it looks like a giant potato. Immediately after the discovery on February 23, 2012, it was found that science was dealing with an unusual celestial body. The fact is that the asteroid’s orbit is in a 1:1 resonance with the Earth. This means that the period of its revolution around the Sun approximately corresponds to an Earth year.
Duende may remain close to Earth for a long time, but astronomers are not yet ready to predict the behavior of the celestial body in the future. Although, according to current calculations, the probability of Duende colliding with the Earth before February 16, 2020 will not exceed one chance in 14,000.

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

An asteroid with such an intriguing name is a long-time acquaintance of earthlings. It was discovered by German astronomer Carl Witt back in 1898 and turned out to be the first near-Earth asteroid discovered. Eros also became the first asteroid to acquire an artificial satellite. We are talking about the NEAR Shoemaker spacecraft, which landed on a celestial body in 2001.
Eros is the largest asteroid in the inner Solar System. Its dimensions are amazing – 33 x 13 x 13 km. The average speed of the giant is 24.36 km/s. The shape of the asteroid is similar to a peanut, which affects the uneven distribution of gravity on it. The impact potential of Eros in the event of a collision with the Earth is simply enormous. According to scientists, the consequences of an asteroid hitting our planet will be more catastrophic than after the fall of Chicxulub, which allegedly caused the extinction of the dinosaurs. The only consolation is that the chances of this happening in the foreseeable future are negligible.

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

This asteroid was discovered by Russian astronomer Gennady Borisov on September 16, 2013 using a homemade 20 cm telescope. The object was immediately called perhaps the most dangerous threat among celestial bodies to the Earth. The diameter of the object is about 400 meters.
The asteroid's approach to our planet is expected on August 26, 2032. According to some assumptions, the block will sweep just 4 thousand kilometers from the Earth at a speed of 15 km/s. Scientists have calculated that in the event of a collision with the Earth, the explosion energy will be 2.5 thousand megatons of TNT. For example, the power of the largest thermonuclear bomb detonated in the USSR is 50 megatons.
Today, the probability of an asteroid colliding with the Earth is estimated at approximately 1/63,000. However, with further refinement of the orbit, the figure may either increase or decrease.