The very first mention of the appearance of a comet is considered to be a record of observations by Chinese astronomers dating from about 2296 BC. This phenomenon was considered a harbinger of misfortune, illness and all sorts of cataclysms. Unable to study them, Aristotle tried to explain these phenomena as atmospheric. Deep research began in the Middle Ages.
The famous astronomer of that time, Regiomontanus, was the first to study the structure of data at that time still completely unexplored cosmic bodies. A little later, the Danish astronomer Tycho Brahe ranked them among the celestial bodies.
Project Vega
This project was developed by Soviet scientists, and consisted of 3 phases: the study of the surface and dynamics of the atmosphere of Venus, and the passage near Halle. The spacecraft was launched from Baikonur in 1984.
Instruments for studying the nucleus of a comet were located on moving platforms, which automatically tracked the position and turned after it.
Comet nucleus, visible ejection of material from the surface
Studies have shown that the Halley core has an elongated irregular shape with a very high temperature and low reflectivity. Measurements of the chemical composition showed that most of the gas is water vapor.
Based on this, it was concluded that her head consists of frozen water interspersed with metal molecules and silicates.
"Tailed stars", as comets were called in ancient times. In Greek, the word "comet" means "hairy". Indeed, these cosmic bodies have a long trail or "tail". Moreover, it is always turned away from the Sun, regardless of the trajectory of movement. The solar wind is to blame for this, which deflects the plume away from the luminary.
Halley's comet belongs just to the company of "hairy" cosmic bodies. It is short-period, that is, it regularly returns to the Sun in less than 200 years. More precisely, it can be seen in the night sky every 76 years. But this figure is not absolute. Due to the influence of the planets, the trajectory of movement can change, and the error due to this is 5 years. The term is quite decent, especially if you look forward to the space beauty.
She was last seen in the Earth's sky in 1986. Before that, she delighted earthlings with her beauty in 1910. The next visit is scheduled for 2062. But a capricious traveler may appear a year earlier or be five years late. Why is this cosmic body so famous, consisting of frozen gas and solid particles interspersed in it?
Here, first of all, it should be noted that the ice visitor has been known to people for more than 2 thousand years. Its first observation dates back to 240 BC. uh. It is not at all excluded that someone has seen this luminous body before, just no data has been preserved about this. After the specified date, it was observed in the sky 30 times. Thus, the fate of the space wanderer is inextricably linked with human civilization.
Further, it should be said that this is the first of all comets in which an elliptical orbit was calculated and the frequency of returning to Mother Earth was determined. Mankind owes this to the English astronomer Edmund Halley(1656-1742). It was he who compiled the very first catalog of the orbits of comets that periodically appear in the night sky. At the same time, he noticed that the paths of movement of 3 comets completely coincide. We saw these travelers in 1531, 1607 and 1682. The Englishman came up with the idea that this is one and the same comet. It revolves around the Sun with a period equal to 75-76 years.
Based on this, Edmund Halley suggested that a bright object would appear in the night sky in 1758. The scientist himself did not live up to this date, although he lived for 85 years. But the impetuous traveler was seen on December 25, 1758 by the German astronomer Johann Palich. And by March 1759, dozens of astronomers had already seen this comet. Thus, Halley's predictions were exactly confirmed, and the systematically returning guest was named after him in the same 1759.
What is Halley's Comet?? Its age lies in the range from 20 to 200 thousand years. Rather, this is not even age, but movement along the existing orbit. Previously, it could be different due to the influence of the gravitational forces of the planets and the Sun.
The core of the space traveler is shaped like a potato and is small in size.. They are 15×8 km. The density is 600 kg / m 3, and the mass reaches 2.2 × 10 14 kg. The core consists of methane, nitrogen, water, carbon and other gases bound by cosmic cold. Solid particles are embedded in the ice. These are mainly silicates, which make up 95% of rocks.
Approaching the luminary, this huge "cosmic snowball" heats up. As a result, the process of evaporation of gases begins. A hazy cloud forms around a comet called coma. In diameter, it can reach 100 thousand km.
The closer to the Sun, the longer the coma becomes. She has a tail that stretches for several million km. This is due to the fact that the solar wind, knocking out gas particles from the coma, throws them far back. In addition to the gas tail, there is also a dust tail. It scatters sunlight, so it looks like a long smoky streak in the sky.
The luminous traveler can already be distinguished at a distance of 11 AU. e. from the luminary. It is perfectly visible in the sky when 2 AU remains to the Sun. e. It goes around the hot star and comes back. Halley's comet flies past the Earth at a speed of about 70 km/s. Gradually, as you move away from the star, its light becomes dimmer, and then the radiant beauty turns into a lump of gas and dust and disappears from view. Its next appearance has to wait more than 70 years. Therefore, astronomers can see a space wanderer only once in a lifetime.
She flies far, far away and disappears in the Oort cloud. It is an impenetrable space abyss at the edge of the solar system. It is there that comets are born, and then begin to travel between planets. They rush to the luminary, go around it and rush back. Our heroine is one of them. But unlike other cosmic bodies, it is closer and dearer to earthlings. After all, her acquaintance with people has been going on for more than 20 centuries.
Alexander Shcherbakov
Comet is an object of the solar system with a central part and a tail. It is the residual material resulting from the emergence of the solar system. The composition of the comet includes: metal, frozen water, methane, stones, ammonia, carbon dioxide, dust.
Comets are some of the most mysterious objects in our system. Despite the fact that knowledge about them is constantly updated, there are still a large number of questions around the presented space objects.
Of great interest to mankind is Halley's comet. She is an old-timer among other comets. It is known that the period of revolution of this object around the Sun is about 77 years. The presented discovery was made by Halley, whose name the comet was named. The object is of great value to people. Thanks to him, the law of gravity was confirmed. Among other things, the comet is the only object that has been observed for the past 22 centuries.
Halley's comet among the family of comets
All comets belong to the family of small bodies. This group also includes asteroids and meteors. But comets are interesting because when they are near the Sun, they grow from small bodies into huge dust shells.
The most popular comet is recognized Halley's comet. What is the reason for the increased interest in it? First of all, the fact that its orbit is tangent to our planet. There are several similar comets, but they are poorly understood. And Halley's object has long been under close observation, and does not lose its combustibility when it meets the Sun.
The average period of revolution of a comet around a star is about 76-77 years. But it can change and be equal to 74 - 79 years. The tail and central part of the comet, which have attracted human attention since ancient times, are actually huge blocks of polluted ice, minerals and dust.
There are 2 meteor showers associated with the comet. One of them is the Orionid, the second is the Aquarid. The latter can be seen from late April to mid-May. At the same time, its peak is celebrated on May 5. You can see it only in the southern hemisphere, if you look at the starry sky. It looks like bright and beautiful meteors gliding across the sky.
The Orionid shower occurs in early October - early November. Its peak falls on October 21st. Despite the fact that the density of this stream is less, it seems to be more abundant, since it is located higher above the horizon. During the shower, if you look at the sky, you can see meteors flying at intervals of 2 minutes. Both streams are one of the most beautiful sights that can be observed from our planet.
Comet Halley(The official name 1P/Halley is a bright short-period comet that returns to the Solar System every 75-76 years. It is the first comet for which the frequency of returns has been determined. Named after E. Halley. Halley's comet is the only short-period comet that is clearly visible to the naked eye.
The speed of Halley's comet with respect to the Earth is one of the largest among all bodies in the solar system. In 1910, when flying past our planet, it was 70.56 km / s.
Halley's comet moves in an elongated orbit with an eccentricity of about 0.97 and an inclination of about 162-163 degrees, which means that this comet is moving at a slight angle to the ecliptic (17-18 degrees)? but in the direction opposite the direction in which the planets move, such movement is called retrograde.
Numerical simulation results show that Halley's comet has been in its current orbit for 16,000 to 200,000 years.
The uniqueness of Halley's comet is that, starting from the oldest observations, at least 30 appearances of the comet have been noted in historical sources. The first reliably identifiable sighting of Halley's comet dates back to 240 BC. e. The last passage of Halley's Comet near Earth was in February 1986. The next approach of the comet to the Earth is expected in the middle of 2061.
Back in the Middle Ages in Europe and China, catalogs of past observations of comets began to be compiled, which are called cometographies. Cometography has proven to be very useful in identifying periodic comets. The most comprehensive modern catalog is Harry Kronk's fundamental five-volume Cometography, which can serve as a guide to the historical appearances of Halley's Comet.
240 BC e.- the first reliable observation of Halley's comet is in the Chinese annals "Shi chi":
In this year (240 B.C.) the panicle star first appeared in an easterly direction; then it was visible to the north. From May 24 to June 23, it was visible to the west ... Paniculata was again visible to the west for 16 days. This year the panicle star was visible to the north, and then to the west. The Dowager Empress died in the summer."
164 BC e.- In 1985, F. R. Stephenson published his observations of Halley's comet found on the Babylonian tablets. On the Babylonian clay cuneiform tablets, in particular, the results of extensive centuries-old observations of the movement of the planets and other celestial events - comets, meteors, atmospheric phenomena are recorded. These are the so-called "astronomical diaries", covering the period from about 750 BC. e. to 70 AD e. Most of the "astronomical diaries" are now kept in the British Museum.LBAT 380: A comet that appeared earlier in the east on the path of Anu, in the region of the Pleiades and Taurus, towards the West […] and passed along the path of Ea.
LBAT 378: [… on the way] Ea in the region of Sagittarius, one cubit ahead of Jupiter, three cubits higher north […]
87 BC e.- Babylonian tablets also contain descriptions of the appearance of Halley's comet on August 12, 87 BC. e.“13(?) the interval between sunset and moonrise was measured at 8 degrees; in the first part of the night, a comet [… long gap due to damage] which in the fourth month, day after day, one unit […] between north and west, its tail is 4 units […]”
Perhaps it was the appearance of Halley's comet that could be reflected on the coins of the Armenian king Tigran the Great, whose crown is decorated with a "star with a curved tail."
12 BC e.- Descriptions of the appearance of Halley's comet are very detailed. In the astronomical chapters of the Chinese chronicle Hou Hanshu, the path in the sky among the Chinese constellations is described in detail, indicating the brightest stars closest to the trajectory. Dio Cassius reports the sighting of the comet within a few days by Rome. Some Roman authors claim that the comet foreshadowed the death of the general Agrippa. Historical and astronomical studies by A. I. Reznikov and O. M. Rapov show that the date of the birth of Christ can be associated with the appearance of Halley's comet 12 BC (Christmas star). For the first time, this possibility was noticed, apparently, by the great Italian medieval artist Giotto di Bondone (1267–1337). Under the influence of the comet of 1301 (almost all European chronicles report about it, and it is noted three times in Russian chronicles), he depicted the comet on the fresco "Adoration of the Magi" in the Arena Chapel in Padua (1305).
66 year- Information about this appearance of Halley's comet with an indication of its path in the sky was preserved only in the Chinese chronicle Hou Hanshu. However, sometimes associated with him is the message of Josephus in the book "Jewish War" about a comet in the form of a sword that preceded the destruction of Jerusalem.
141 years old- This appearance of Halley's comet was also reflected only in Chinese sources: in detail in Hou Hanshu, in less detail in some other chronicles.
218 year- The path of Halley's comet is described in detail in the astronomical chapters of the Hou Hanshu chronicle. It is likely that Cassius Dio connected the overthrow of the Roman emperor Macrinus with this comet.
295 year- Halley's comet is reported in the astronomical chapters of the Chinese dynastic histories "Book of Song" and "Book of Chen".
374 year- The appearance is described in the annals and astronomical chapters of the Book of Song and the Book of Chen. The comet approached the Earth by only 0.09 AU. e.
451- The appearance is described in several Chinese chronicles. In Europe, the comet was observed during the invasion of Attila and was perceived as a sign of future wars, described in the chronicles of Idacius and Isidore of Seville.
530 year- The appearance of Halley's comet is described in detail in the Chinese dynastic "Book of Wei" and in a number of Byzantine chronicles. John Malala reports:
In the same reign (Justinian I) a large, terrifying star appeared in the west, from which a white beam went up and lightning was born. Some called it a torch. It shone for twenty days, and there was a drought, in the cities there were murders of citizens and many other terrible events.
607- The appearance of Halley's comet is described in Chinese chronicles and in the Italian chronicle of Paul Deacon: "Then, also in April and May, a star appeared in the sky, which was called a comet." Although the Chinese texts give the path of the comet in the sky in accordance with modern astronomical calculations, the reported dates show confusion and a discrepancy with the calculation of about a month, probably due to chronicler errors. There is no such discrepancy for previous and subsequent appearances.684- This bright appearance caused fear in Europe. According to Schedel's Nuremberg Chronicle, this "tailed star" was responsible for three months of continuous downpours that ruined crops, accompanied by violent lightning that killed many people and livestock. The path of the comet in the sky is described in the astronomical chapters of the Chinese dynastic histories The Book of Tang and The Initial History of Tang. There are also records of observations in Japan, Armenia (the source dates it to the first year of the reign of Ashot Bagratuni) and Syria.
760 year- The Chinese dynasty chronicles "Book of Tang" "Initial History of Tang" and "New Book of Tang" give almost the same details about the path of Halley's comet, which was observed for more than 50 days. The comet is reported in the Byzantine "Chronography" of Theophanes and in Arabic sources.
837- during this appearance, Halley's comet approached the minimum distance to the Earth for the entire time of observations (0.0342 AU) and was 6.5 times brighter than Sirius. The path and appearance of the comet is described in detail in the astronomical chapters of the Chinese dynastic histories The Book of Tang and The New Book of Tang. The maximum length of the forked tail visible in the sky exceeded 80°. The comet is also described in Japanese, Arabic and many European chronicles. The comet is noted in 7 Chinese and 3 European detailed descriptions. The interpretation of its appearance for the emperor of the Frankish state Louis I the Pious, as well as the description in the text of many other astronomical phenomena by the anonymous author of the essay "The Life of the Emperor Louis" allowed historians to give the author the code name Astronomer. This comet horrified the French king Louis the Short.
912- Descriptions of Halley's comet have been preserved in the sources of China (the most detailed), Japan, Byzantium, Rus' (borrowed from Byzantine chronicles), Germany, Switzerland, Austria, France, England, Ireland, Egypt and Iraq. The Byzantine historian of the 10th century, Leo the Grammarian, writes that the comet looked like a sword. In the chronicle of George Amartolus under 912 (Greek text): "At the same time, a comet star appeared in the west, which they say was called a spear, and it heralds bloodshed in the city." The first news of Russian chroniclers in the Laurentian list that the comet passed through perihelion on July 12. "The Tale of Bygone Years": "In the summer of 6419. A great star appeared in the west in a spear way." Earlier comets are not indicated at all in Russian chronicles.
989- Halley's comet is described in detail in the astronomical chapters of the Chinese dynastic "history of the Song", noted in Japan, Korea, Egypt, Byzantium and in many European chronicles, where the comet is often associated with the ensuing plague epidemic.
1066- Halley's comet approached the Earth at a distance of 0.1 AU. e. It was observed in China, Korea, Japan, Byzantium, Armenia, Egypt, in the Arab East and in Rus'. In Europe, this appearance is one of the most mentioned in the chronicles. In England, the appearance of the comet was interpreted as an omen of the imminent death of King Edward the Confessor and the subsequent conquest of England by William I. The comet is described in many English chronicles and depicted on the famous 11th-century Bayeux carpet depicting the events of this time. The comet is possibly depicted on a petroglyph located in the Chaco National Park, in the US state of New Mexico.
1145- The appearance of Halley's comet is recorded in many chronicles of the West and East. In England, the Canterbury monk Edwin sketched a comet in the Psalter.
1222- Halley's comet was observed in September and October. It is noted in the chronicles of Korea, China and Japan, in many European monastic annals, Syrian chronicles and Russian chronicles. There is not supported by historical evidence, but echoing the message in the Russian chronicles (see below), that Genghis Khan took this comet as a call to march to the West.
1301- Many European chronicles report about Halley's comet, including Russian chronicles. Impressed by the observation, Giotto di Bondone depicted the Star of Bethlehem as a comet on the fresco "Adoration of the Magi" in the Scrovegni Chapel in Padua (1305).
1378- This appearance of Halley's Comet was not particularly remarkable due to the unfavorable observation conditions near the Sun. The comet was observed by Chinese, Korean and Japanese court astronomers and possibly in Egypt. There is no information about this appearance in European chronicles.
1456- This appearance of Halley's comet marks the beginning of astronomical studies of the comet. She was discovered in China on May 26. The comet's most valuable observations were made by the Italian physician and astronomer Paolo Toscanelli, who carefully measured its coordinates almost every day from June 8 to July 8. Important observations were also made by the Austrian astronomer Georg Purbach, who first tried to measure the parallax of a comet and found that the comet was at a distance of "more than a thousand German miles" from the observer. In 1468, an anonymous treatise "De Cometa" was written for the Pope Paul II, which also provides the results of observations and determination of the coordinates of the comet.
1531- Peter Apian first noticed that the tail of Halley's Comet always points away from the Sun. The comet was also observed in Rus' (there is an entry in the annals).
1607- Halley's comet was observed by Johannes Kepler, who decided that the comet was moving through the solar system in a straight line.
1682 Halley's comet was observed by Edmund Halley. He discovered similarities in the orbits of comets in 1531, 1607, and 1682, suggested that it was one periodic comet, and predicted the next appearance in 1758. This prediction was ridiculed in Gulliver's Travels by Jonathan Swift (published 1726-1727). The scientists of Laputa in this satirical novel fear “that the future comet, which they calculated to appear in thirty-one years, would in all probability destroy the earth…”
1759- First predicted appearance of Halley's comet. The comet passed through perihelion on March 13, 1759, 32 days later than A. Clairaut's prediction. It was discovered on Christmas Day 1758 by amateur astronomer I. Palich. The comet was observed until mid-February 1759 in the evening, then disappeared against the background of the Sun, and from April became visible in the pre-dawn sky. The comet reached approximately zero magnitude and had a tail that extended 25°. It was visible to the naked eye until the beginning of June. The last astronomical observations of the comet were made at the end of June.
1835- Since not only the date of passage of perihelion by Halley's comet was predicted for this appearance, but also the ephemeris was calculated, astronomers began to look for the comet with telescopes from December 1834. Halley's comet was discovered as a weak point on August 6, 1835 by the director of a small observatory in Rome, S. Dumushel. On August 20, in Dorpat, it was rediscovered by V. Ya. Struve, who, two days later, was able to observe the comet with the naked eye. In October, the comet reached magnitude 1 and had a tail about 20° long. V. Ya. Struve in Dorpat, using a large refractor, and J. Herschel on an expedition to the Cape of Good Hope, made many sketches of a comet that constantly changed its appearance. Bessel, who also followed the comet, concluded that its motion is significantly affected by non-gravitational reactive forces of gases evaporating from the surface. On September 17, V. Ya. Struve observed the occultation of a star by the head of a comet. Since no change in the brightness of the star was recorded, this made it possible to conclude that the material of the head is extremely rarefied and its central core is extremely small. The comet passed perihelion on November 16, 1835, just a day later than the prediction of F. Pontekulan, which allowed him to clarify the mass of Jupiter, taking it equal to 1/1049 of the mass of the Sun (the modern value is 1/1047.6). J. Herschel followed the comet until May 19, 1836.
1910- During this appearance, Halley's comet was photographed for the first time and spectral data on its composition were obtained for the first time. The minimum distance from the Earth was only 0.15 AU. e., and the comet was a bright celestial phenomenon. The comet was discovered on an approach on September 11, 1909, on a photographic plate by M. Wolf in Heidelberg using a 72-cm reflecting telescope equipped with a camera, in the form of an object of 16-17 magnitude (the photographic exposure was 1 hour). An even fainter image was later found on a photographic plate taken on 28 August. The comet passed perihelion on April 20 (3 days later than F. H. Cowell and E. C. D. Crommelin predicted) and was a bright sight in the predawn sky in early May. At this time, Venus passed through the tail of the comet. On May 18, the comet was exactly between the Sun and the Earth, which also plunged into the comet's tail for several hours, which is always directed away from the Sun. On the same day, May 18, the comet passed across the disk of the Sun. Observations in Moscow were carried out by V.K. Tserasky and P.K. Shternberg using a refractor with a resolution of 0.2-0.3″, but they could not distinguish the nuclei. Since the comet was at a distance of 23 million km, this made it possible to estimate that its size is less than 20-30 km. The same result was obtained from observations in Athens. The correctness of this estimate (the maximum size of the core turned out to be about 15 km) was confirmed during the next appearance, when the core was studied at close range using spacecraft. At the end of May - beginning of June 1910, the comet was of magnitude 1, and its tail was about 30° long. After May 20, it began to rapidly move away, but was recorded photographically until June 16, 1911 (at a distance of 5.4 AU).
A spectral analysis of the comet's tail showed that it contained the poisonous gas cyanogen and carbon monoxide. Since the Earth was supposed to pass through the tail of a comet on May 18, this discovery provoked doomsday predictions, panic and hype for quack “anti-comet pills” and “anti-comet umbrellas”. In fact, as many astronomers were quick to point out, the comet's tail is so rarefied that it cannot have any negative effects on the earth's atmosphere. On May 18 and in the following days, various observations and studies of the atmosphere were organized, but no effects that could be associated with the action of the cometary substance were found.
The famous American humorist Mark Twain wrote in his autobiography in 1909: “I was born in 1835 with Halley's comet. She will reappear next year and I think we will disappear together. If I don't disappear with Halley's comet, it will be the biggest disappointment of my life. God probably decided: here are two bizarre inexplicable phenomena, they arose together, let them disappear together.. And so it happened: he was born on November 30, 1835, two weeks after the comet passed perihelion, and died on April 21, 1910, the day after the next perihelion.
1986- The appearance of Halley's comet in 1986 was one of the most unspectacular in history. in 1966 Brady wrote: “It turns out that Halley's comet in 1986 would not be a good object to observe with a telescope from Earth. When passing through perihelion on February 5, 1986, the comet will be almost in conjunction with the Sun, and when it emerges from behind the Sun, it will be observed in the Southern Hemisphere. The best time to observe in the northern hemisphere will be during the first opposition, when the comet is at a distance of 1.6 AU. from the Sun and 0.6 AU from Earth, the declination will be 16° and the comet will be visible all night.”
In February 1986, during the passage of perihelion, the Earth and Halley's comet were on opposite sides of the Sun, which made it impossible to observe the comet during the period of greatest brightness, when the size of its tail was maximum. In addition, due to increased light pollution since the last appearance due to urbanization, the majority of the population could not observe the comet at all. In addition, when the comet was bright enough in March and April, it was almost invisible in the Northern Hemisphere of the Earth. The approach of Halley's Comet was first recorded by astronomers Jewitt and Danielson on October 16, 1982, using the Palomar Observatory's 5.1-m CCD Hale Telescope.
The first person to visually observe the comet during its return in 1986 was amateur astronomer Stephen James O'Meara, who on January 24, 1985, from the top of Mauna Kea, using a homemade 60-cm telescope, was able to detect guest, which at that time had a magnitude of 19.6. Steven Edberg (who worked as the observing coordinator for amateur astronomers at NASA's Jet Propulsion Laboratory) and Charles Morris were the first to see Halley's comet with the naked eye. From 1984 to 1987, there were two programs for observing the comet: the Soviet SoProG and the international program The International Halley Watch (IHW).
After the end of the Venus exploration program, the Soviet interplanetary stations "Vega-1" and "Vega-2" flew past the comet (the name of the vehicles stands for "Venus-Halley" and indicates the route of the apparatus and the purpose of its research). Vega-1 began transmitting images of Halley's comet on March 4, 1986 from a distance of 14 million km, it was with the help of this apparatus that it was possible for the first time in history to see the nucleus of a comet. Vega-1 flew past the comet on March 6 at a distance of 8879 km. During the flight, the spacecraft was subjected to a strong impact of cometary particles at a collision velocity of ~78 km/s, as a result of which the power of the solar panels fell by 45%, but remained operational. Vega-2 flew past the comet at a distance of 8045 km on March 9. In total, Vega transmitted more than 1,500 images to Earth. The measurement data of the two Soviet stations were, in accordance with a joint research program, used to correct the orbit of the space probe of the European Space Agency "Giotto", which was able to fly even closer on March 14, to a distance of 605 km (unfortunately, earlier, at a distance of about 1200 km, from - due to a collision with a fragment of a comet, the Giotto TV camera failed, and the device lost control). A certain contribution to the study of Halley's comet was also made by two Japanese vehicles: Suisei (flight on March 8, 150 thousand km) and Sakigake (March 10, 7 million km, was used to guide the previous device). The five spacecraft that explored the comet were given the unofficial name of Halley's Armada.
February 12, 1991 at a distance of 14.4 a. e. Halley's comet suddenly had an ejection of matter that lasted several months and released a cloud of dust about 300,000 km across. Halley's Comet was last observed March 6-8, 2003 by three ESO Very Large Telescopes in Cerro Paranal, Chile, when it was magnitude 28.2 and passed 4/5 of the distance to its farthest point in its orbit. These telescopes observed the comet at a comet-record distance (28.06 AU or 4200 million km) and magnitude in order to work out methods for searching for very faint trans-Neptunian objects. Astronomers can now observe the comet at any point in its orbit. The comet will reach aphelion in December 2023, after which it will begin to approach the Sun again. Comet on a 2006 Ukrainian postage stamp
The next perihelion passage of Halley's comet is expected on July 28, 2061, when its position will be more convenient for observation than during the passage in 1985-1986, since it will be on the same side of the Sun as the Earth at perihelion. Its apparent magnitude is expected to be −0.3, compared to +2.1 in 1986. On September 9, 2060, Halley's comet will pass at a distance of 0.98 AU. e. from Jupiter, and then on August 20, 2061 it will approach at a distance of 0.0543 a. e. (8.1 million km) to Venus. In 2134, Halley's Comet is expected to pass at a distance of 0.09 AU. e. (13.6 million km) from the Earth. Its apparent magnitude during this appearance will be around −2.0.
HALLEY COMET, named after E. Halley, who in 1705 predicted its next appearance near the Earth in 1758. The prediction was based on Newton's theory of gravity and a comparison of observations of a bright comet in 1531, 1607 and 1682, which, as Halley suggested, referred to the same comet. Later it turned out that the same comet was observed as early as 240 BC by Chinese astronomers, and also, probably, in 164 BC in Babylon. In a number of works of art, the appearance of Halley's comet is associated with the Star of Bethlehem.
The average period of Halley's revolution of a comet around the Sun is 76 years. The last appearance of Halley's comet near the Sun occurred in 1986, the next is expected in mid-2061. Halley's comet moves in an elliptical orbit with a semi-major axis of 17.9 AU, an eccentricity of 0.97 and an inclination to the ecliptic plane of 162 °, that is, in the inverse compared to the planets in the direction around the Sun, approaching it at perihelion to a distance of 0.59 AU. (about 80 million km) and moving away from it at aphelion at a distance of 35.1 AU. (about 5.2 billion km), that is, beyond the orbit of Neptune.
During the passage of Halley by the comet of perihelion in 1986, spacecraft (SC) were sent to it by different countries. The most successful were the flybys near the comet's nucleus (1000-380 km) of the Soviet spacecraft "Vega-1" and "Vega-2" and the European spacecraft "Giotto", which made it possible to obtain data on the size of the nucleus, its chemical composition, the properties of the atmosphere and dust particles .
The transmitted television images show an irregularly shaped core and an uneven outflow of gas and dust material that forms a cometary atmosphere (coma). The size of the coma reaches 100,000 km, and the tail formed from it extends for tens of millions of kilometers. The comet's nucleus measures 8x7x16 km. Core composition: about 80% water ice, 10% carbon monoxide, 2.5% mixture of methane and ammonia in the solid phase, as well as iron, sodium, hydrocarbons, hydrogen cyanide and some other compounds. The density of the nucleus is estimated at 200-1200 kg/m 3 , that is, the comet's Halley nucleus is quite loose and porous, which corresponds to the "dirty snowball" model with inclusions of rock fragments. The albedo of the core surface is extremely small (about 0.035), which is probably due to the layer of carbon and organic compounds covering it; this contributes to the absorption of sunlight and intense degassing. Due to the removal of a large amount of dust during the sublimation of the substance of the nucleus along the Halley orbit of the comet, a dust torus is formed. In its movement around the Sun, the Earth crosses it twice, which is the reason for the occurrence of meteor showers in May and October.
With each approach to Halley's Sun, the comet loses more than a billion tons of matter (about 0.2% of its mass) and must completely exhaust the volatile components of the nucleus in about 500 revolutions, that is, in about 40 thousand years. It is possible, however, that even earlier the surface of the nucleus will be covered with a dense dust crust, which prevents the sublimation of ice, and the comet will turn into an asteroid-like body. There is also a possibility that under the influence of deformations the core will break up into several fragments.
Lit .: Belyaev N. A., Churyumov K. I. Halley's Comet and its observation. M., 1985.
