School encyclopedia. The amazing story of Comet Halley Astrophysical features of the comet

The very first mention of the appearance of a comet is considered to be a record of observations by Chinese astronomers, dating back to approximately 2296 BC. This phenomenon was considered a harbinger of misfortunes, illnesses and all kinds of disasters. Unable to study them, Aristotle tried to explain these phenomena as atmospheric. In-depth research began in the Middle Ages.

The famous astronomer of that time, Regiomontanus, was the first to begin studying the structure of data on cosmic bodies that were still completely unknown at that time. 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: studying the surface and dynamics of the atmosphere of Venus, and passing near Halley. The spacecraft launched from Baikonur in 1984.

Instruments for studying the comet's nucleus were located on moving platforms that automatically tracked the position and turned after it.

Comet nucleus showing ejection of material from surface

Studies have shown that Halley's core has an elongated, irregular shape with a very high temperature and low reflectivity. Chemical composition measurements showed that most of the gas was water vapor.

Based on this, it was concluded that her head consists of frozen water interspersed with molecules of metals and silicates.

“Tailed stars” is what comets were called in ancient times. Translated from 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, deflecting the plume away from the star.

Halley's Comet belongs 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 planets, the trajectory of movement may change, and the error due to this is 5 years. The period is quite decent, especially if you wait impatiently for the space beauty.

It 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 the capricious traveler may appear a year earlier or five years late. Why is this cosmic body, consisting of frozen gas and solid particles embedded in it, so famous?

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 impossible that someone has seen this luminous body before, it’s just that no data has been preserved about it. 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.

It should further be said that this is the first of all comets for which an elliptical orbit was calculated and the periodicity of its return to Mother Earth was determined. Humanity 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 coincided. These travelers were seen in 1531, 1607 and 1682. The Englishman came up with the idea that this was the same comet. It revolves around the Sun with a period of 75-76 years.

Based on this, Edmund Halley predicted that a bright object would appear in the night sky in 1758. The scientist himself did not live to see this date, although he lived for 85 years. But the swift traveler was seen on December 25, 1758 by the German astronomer Johann Palitsch. And by March 1759, this comet had already been seen by dozens of astronomers. 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 ranges from 20 to 200 thousand years. Or rather, it’s not even age, but movement along the existing orbit. Previously, it could have been 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 15x8 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 the cosmic cold. There are solid particles embedded in the ice. These are mainly silicates, of which 95% of rocks are composed.

Approaching the star, this huge “cosmic snowball” heats up. As a result, the process of evaporation of gases begins. A nebulous cloud forms around the comet, called coma. In diameter it can reach 100 thousand km.

The closer to the Sun, the longer the coma becomes. It develops a tail that stretches for several million km. This happens because the solar wind, knocking gas particles out of the coma, throws them far back. In addition to the gas tail, there is also a dust tail. It scatters sunlight so it appears as a long, hazy streak in the sky.

The luminous traveler can already be distinguished at a distance of 11 a.m. e. from the luminary. It is clearly visible in the sky when there are 2 au left to the Sun. e. She goes around the glowing star and returns back. Comet Halley flies past the Earth at a speed of approximately 70 km/s. Gradually, as it moves away from the star, its light becomes increasingly dimmer, and then the shining beauty turns into a lump of gas and dust and disappears from view. You have to wait more than 70 years for her next appearance. Therefore, astronomers can see a space wanderer only once in a lifetime.

She flies far, far away and disappears into the Oort cloud. It is an impenetrable cosmic abyss at the edge of the solar system. It is there that comets are born and then begin to travel between planets. They rush towards the star, 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 2 decades.

Alexander Shcherbakov

Halley's Comet(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 return period was determined. Named in honor of E. Halley. Halley’s Comet is the only short-period comet clearly visible to the naked eye.

The speed of Halley's comet relative to the Earth is one of the highest among all bodies in the Solar System. In 1910, when flying past our planet, it was 70.56 km/s.

Halley's Comet is moving 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 direction of planetary movement, such movement is called retrograde.

Numerical modeling results indicate 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 since the earliest 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 Comet Halley near Earth was in February 1986. The comet's next approach to Earth is expected in mid-2061.

Back in the Middle Ages, Europe and China began to compile catalogs of past observations of comets, which are called cometographies. Cometographs have proven very useful in identifying periodic comets. The most comprehensive modern catalog is Harry Cronk's seminal 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 Ji”:

In this year (240 BC) the paniculate star first appeared in an eastern direction; then it was visible in a northerly direction. From May 24 to June 23 it was visible in a westerly direction... The paniculate star was again visible in a westerly direction for 16 days. This year the paniculate star was visible in a northern direction, and then in a western direction. The Empress Dowager died in the summer.”

164 BC e.- In 1985, F. R. Stephenson published observations of Halley's Comet that he discovered on the Babylonian tablets. The Babylonian clay cuneiform tablets, in particular, record the results of extensive centuries-long observations of the movements of the planets and other celestial events - comets, meteors, atmospheric phenomena. These are the so-called “astronomical diaries”, covering the period from approximately 750 BC. e. to 70 AD e. Most of the “astronomical diaries” are now kept in the British Museum.

LBAT 380: A comet that previously appeared 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 in front of Jupiter, three cubits higher to the north […]

87 BC e.- Descriptions of the appearance of Halley's comet on August 12, 87 BC were also found on Babylonian tablets. e.

“13 (?) the interval between sunset and moonrise was measured at 8 degrees; in the first part of the night, the comet [... long pass due to damage] which in the IV month, day after day, one unit […] between the north and west, its tail 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. The astronomical chapters of the Chinese chronicle “Hou Hanshu” describe in detail the path in the sky among the Chinese constellations, indicating the bright stars closest to the trajectory. Dio Cassius reports sightings of a comet over several 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 may be associated with the appearance of Halley's comet in 12 BC (Christmas star). Apparently, the great Italian medieval artist Giotto di Bondone (1267–1337) was the first to draw attention to this possibility. Influenced by the comet of 1301 (almost all European chronicles report on it, and it is noted three times in Russian chronicles), he depicted the comet in the fresco “Adoration of the Magi” in the Arena Chapel in Padua (1305).

'66- Information about this appearance of Halley’s comet, indicating its path in the sky, was preserved only in the Chinese chronicle “Hou Hanshu”. However, it is sometimes associated with Josephus' account in the book The Jewish War of a sword-shaped comet 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 the “Hou Hanshu”, in less detail in some other chronicles.

218- The path of Halley's comet is described in detail in the astronomical chapters of the chronicle “Hou Hanshu”. Cassius Dio probably associated the overthrow of the Roman Emperor Macrinus with this comet.

295- Halley's comet is reported in the astronomical chapters of the Chinese dynasty histories "Book of Song" and "Book of Chen".

374- The appearance is described in the annals and astronomical chapters of the Book of Song and Book of Chen. The comet approached Earth at 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 Idatius and Isidore of Seville.

530- 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:

During the same reign (of Justinian I), a large, terrifying star appeared in the west, from which a white ray went upward and lightning was born. Some called her 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 the Chinese chronicles and in the Italian chronicle of Paul the 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, there is confusion in the reported dates and a discrepancy of about a month with the calculation, probably due to errors of the chronicler. 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 rainfall that destroyed crops, accompanied by strong lightning that killed many people and livestock. The path of a 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 sightings in Japan, Armenia (the source dates it to the first year of the reign of Ashot Bagratuni) and Syria.

760- The Chinese dynastic chronicles “Book of Tang” “Elementary History of Tang” and “New Book of Tang” give almost identical 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, Comet Halley approached the minimum distance to the Earth for the entire period of observations (0.0342 AU) and was 6.5 times brighter than Sirius. The path and appearance of the comet are described in detail in the astronomical chapters of the Chinese dynastic histories “Book of Tang” and “New Book of Tang”. The length of the forked tail visible in the sky at its maximum 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 descriptions in the text of many other astronomical phenomena by the anonymous author of the essay “The Life of Emperor Louis” allowed historians to give the author the conventional name Astronomer. This comet terrified the French king Louis the Short.

912- Descriptions of Halley's comet are preserved in sources from China (the most detailed), Japan, Byzantium, Rus' (borrowed from Byzantine chronicles), Germany, Switzerland, Austria, France, England, Ireland, Egypt and Iraq. The 10th-century Byzantine historian Leo Grammaticus writes that the comet had the shape of a sword. In the chronicle of George Amartol under 912 (Greek text): “At this 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 is 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 the form of a spear.” 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 dynasty "history of the Song", noted in Japan, Korea, Egypt, Byzantium and in many European chronicles, where the comet is often associated with the subsequent 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, the Arab East and Rus'. In Europe, this appearance is one of the most mentioned in 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 is depicted on the famous Bayeux carpet of the 11th century, depicting the events of this time. The comet may be depicted on a petroglyph located in 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 in Russian chronicles. There is a report, not supported by historical evidence, but echoing the message in Russian chronicles (see below) that Genghis Khan took this comet as a call to march to the West.

1301- Many European chronicles, including Russian chronicles, report on Halley’s comet. Impressed by the observation, Giotto di Bondone depicted the Star of Bethlehem as a comet in the fresco “Adoration of the Magi” in the Scrovegni Chapel in Padua (1305).

1378- This appearance of Halley's Comet was not particularly noteworthy due to unfavorable observing 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 research on the comet. She was discovered in China on May 26. The most valuable observations of the comet 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 located at a distance of “more than a thousand German miles” from the observer. In 1468, the anonymous treatise “De Cometa” was written for Pope Paul II, which also presents the results of observations and determination of the coordinates of the comet.

1531- Peter Apian first noticed that the tail of Halley's Comet is always directed away from the Sun. The comet was also observed in Rus' (there is a record in the chronicles).

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 the similarity of the orbits of comets in 1531, 1607 and 1682, suggested that they were one periodic comet, and predicted the next appearance in 1758. This prediction was ridiculed by Jonathan Swift in Gulliver's Travels (published in 1726-1727). Laputa's scientists in this satirical novel fear “that the coming comet, which, according to their calculations, is expected to appear in thirty-one years, will, 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 it became visible in the pre-dawn sky. The comet reached approximately zero magnitude and had a tail extending 25°. It was visible to the naked eye until early June. The last astronomical observations of the comet were made at the end of June.

1835- Since not only the date of passage of Halley’s comet perihelion was predicted for this appearance, but also the ephemeris was calculated, astronomers began searching for the comet using telescopes in 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. Dumouchel. 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 1st magnitude and had a tail extending about 20°. V. Ya. Struve in Dorpat with the help of a large refractor and J. Herschel on an expedition to the Cape of Good Hope made many sketches of a comet that was constantly changing its appearance. Bessel, who also monitored the comet, concluded that its movement was significantly influenced by the 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 star’s brightness was recorded, this allowed us to conclude that the substance of the head was extremely rarefied and its central core was extremely small. The comet passed perihelion on November 16, 1835, just a day later than the prediction of F. Ponteculane, which allowed him to clarify the mass of Jupiter, taking it equal to 1/1049 of the mass of the Sun (modern value 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 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 shutter speed when photographing was 1 hour). An even fainter image was later found on a photographic plate obtained on August 28. The comet passed perihelion on April 20 (3 days later than predicted by F.H. Cowell and E.C.D. Crommelyn) and was a bright spectacle in the predawn sky in early May. At this time, Venus passed through the comet's tail. On May 18, the comet found itself exactly between the Sun and the Earth, which also plunged into the comet's tail, which is always directed away from the Sun, for several hours. 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. Sternberg using a refractor with a resolution of 0.2-0.3″, but were unable to distinguish the nuclei. Since the comet was at a distance of 23 million km, this made it possible to estimate that its size was 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 was about 15 km) was confirmed during the next appearance, when the core was examined at close range using spacecraft. At the end of May - beginning of June 1910, the comet had 1st magnitude, and its tail had a length of about 30°. After May 20, it began to move away quickly, but was photographically recorded until June 16, 1911 (at a distance of 5.4 AU).

Spectral analysis of the comet's tail showed that it contains poisonous cyanogen gas and carbon monoxide. With the Earth set to pass through the comet's tail on May 18, the discovery sparked doomsday predictions, panic, and a rush to buy quack "anti-comet pills" and "anti-comet umbrellas." In fact, as many astronomers were quick to point out, the comet's tail is so thin that it cannot have any negative effects on the Earth's atmosphere. On May 18 and 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 detected.

The famous American humorist Mark Twain wrote in his autobiography in 1909: “I was born in 1835 along with Halley’s Comet. She will appear again next year and I think we will disappear together. If I don't disappear with Halley's Comet, it will be the greatest disappointment of my life. God probably decided: these 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 will not be a good object to observe with a telescope from Earth. At perihelion on February 5, 1986, the comet will be almost in conjunction with the Sun, and when it leaves the Sun, it will be visible in the Southern Hemisphere. The best viewing time in the northern hemisphere will be during first opposition, when the comet will be 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 due to urbanization since the last appearance, most of the population was unable to observe the comet at all. Additionally, when the comet was bright enough in March and April, it was almost invisible in Earth's Northern Hemisphere. The approach of Halley's Comet was first detected by astronomers Jewitt and Danielson on October 16, 1982, using Palomar Observatory's 5.1-m CCD Hale Telescope.

The first person to visually observe the comet during its 1986 return 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 an observation 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, two programs to observe the comet took place: the Soviet SoProG and the international program The International Halley Watch (IHW).

After the end of the Venus research program, the Soviet interplanetary stations “Vega-1” and “Vega-2” flew past the comet (the name of the devices stands for “Venus - Halley” and indicates the route of the device and the goals of its research). Vega-1 began transmitting images of Halley's comet on March 4, 1986 from a distance of 14 million km, and it was with the help of this device that the comet's nucleus was seen for the first time in history. Vega 1 flew past the comet on March 6 at a distance of 8879 km. During the flight, the spacecraft was heavily impacted by cometary particles at a collision speed of ~78 km/s, as a result of which the power of the solar panels dropped 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. Measurement data from two Soviet stations were, in accordance with a joint research program, used to correct the orbit of the European Space Agency's Giotto space probe, 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 television camera failed and the device lost control). Two Japanese spacecraft also made a certain contribution to the study of Halley's comet: Suisei (flight on March 8, 150 thousand km) and Sakigake (March 10, 7 million km, used to guide the previous spacecraft). The five spacecraft that explored the comet were unofficially called Halley's Armada.

February 12, 1991 at a distance of 14.4 a. That is, Halley's comet suddenly experienced an ejection of material that lasted several months and released a cloud of dust about 300,000 km across. Halley's Comet was last observed on 6-8 March 2003 by ESO's three Very Large Telescopes at Cerro Paranal, Chile, when it had a magnitude of 28.2 and was 4/5 the distance from its farthest point in its orbit. These telescopes observed the comet at a record distance for comets (28.06 AU or 4200 million km) and magnitude in order to develop methods for searching for very dim trans-Neptunian objects. Now astronomers can 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 Comet Halley is expected on July 28, 2061, when its location will be more convenient for observation than during its passage in 1985-1986, since at perihelion it will be on the same side of the Sun as the Earth. Its apparent magnitude is expected to be −0.3, down from +2.1 in 1986. On September 9, 2060, Comet Halley will pass at a distance of 0.98 AU. e. from Jupiter, and then on August 20, 2061 will approach at a distance of 0.0543 a. e. (8.1 million km) to Venus. In 2134, Comet Halley is expected to pass at a distance of 0.09 AU. e. (13.6 million km) from Earth. Its apparent magnitude at the time of this appearance will be about −2.0.

Halley's Comet is undoubtedly the most popular of the comets. With amazing consistency, approximately every 76 years it appears nearby, and every time for 22 centuries, earthlings have recorded this rare event. Let us clarify that the comet's orbital period varies from 74 to 79 years, so 76 years is the average period over the past centuries.

Not all appearances of Halley's comet in the earth's sky were remarkable. Sometimes, however, the brilliance of its core exceeded the brilliance of Venus during the period of the planet’s best visibility. In such cases, the comet's tails became long and spectacular, and records in the annals reflected the excitement of observers caused by the "ominous" tailed star. In other years, the comet looked like a dim, foggy star with a small tail, and then the entries in the chronicles were very brief.

Over the past 2000 years, Halley's Comet has never approached Earth closer than 6 million km. Approach to Earth in 1986 was the most unfavorable in the entire history of observations of the comet - the conditions for its visibility from Earth were the worst.

For those who have never seen a real comet, but judge the appearance of comets from drawings in books, let us inform you that the surface brightness of comet tails never exceeds the brightness of the Milky Way. Therefore, in the conditions of any large modern city, a comet is no easier to see than the Milky Way. At best, it is possible to view its core in the form of a more or less bright, slightly hazy and somewhat “smeared” star. But where the sky is clear, its background is black, and the scattering of stars of the Milky Way is clearly visible, a large comet with bright tails is, of course, an unforgettable sight.

Not all people are able to see the passage of Comet Halley near the Earth twice in their lives. Still, 76 years is a long period, close to the average duration of human life, and therefore the list of famous people who twice observed the return of Halley’s comet is not so long.

Among them we find Johann Halle (1812-1910) - the astronomer who discovered the planet Neptune according to the predictions of W., Caroline Herschel (1750 -1848) - the sister of the famous founder of stellar astronomy, Leo Tolstoy (1828-1910) and others. It is curious that the famous American writer Mark Twain was born two weeks after the appearance of Halley's Comet in 1835, and died the day after its next closest approach to the Sun in 1910. Not long before this, Mark Twain jokingly told his friends that since he was born in the year of the next appearance of Halley's Comet, he would die immediately after its next return!

It is interesting to trace how the Earth greeted the famous comet throughout the history of its observations. Only in 1682 They suspected that they were dealing with a periodic comet. In 1759 this suspicion was confirmed. But this year, as well as the next visit of the comet in 1835, astronomers were only able to conduct telescopic observations of this cosmic body, which said little about its physical nature. Only in 1910 Scientists met Halley's Comet fully armed. The comet flew near the Earth, touching it (in May 1910) with its tail. It was very convenient to observe it from Earth, and photography, spectroscopy and photometry were already in the arsenal of astronomers.

By that time, the great Russian comet explorer Fyodor Aleksandrovich (1831-1904) had created a mechanical theory of cometary forms, and his followers were able to successfully apply the new theory to the interpretation of observed cometary phenomena. In general, the previous meeting with Halley's comet in 1910. can be called a holiday of cometary astronomy. At this time, the foundations of the modern physical theory of comets were laid, and it would not be an exaggeration to say that current ideas about comets owe much to the successes of 1910.

Comet Halley made its thirtieth return to the Sun in 1986. received an unusual reception. For the first time, spacecraft flew to the comet in order to explore it in close proximity. Soviet scientists, led by academician R.Z. Sagdeev, developed and implemented the Vega project - sending special interplanetary stations Vega-1 and Vega-2 to the comet. Their task was to photograph the nucleus of Halley's comet from close range and study the processes occurring in it. The European project “Giotto” and the Japanese projects “Planet-A” and “Planet-B” were also part of the international research program for Halley’s Comet, which began to be developed back in 1979.

Now it is pleasant to state that this program has been successfully completed, and during its implementation fruitful international cooperation between scientists from different countries was evident. For example, during the implementation of the Giotto program, American specialists helped restore normal communication with the station, and later Soviet scientists ensured its flight at a given distance from the cometary nucleus.

Astronomical tracking stations brought considerable benefit in receiving information from stations flying near Halley's comet. Now, with our common efforts, we can imagine what Halley’s comet is and, therefore, what comets in general are like. The main part of the comet - its nucleus - is an elongated body of irregular shape with dimensions of 14x7.5x7.5 km. It rotates around its axis with a period of about 53 hours. This is a huge block of contaminated ice, which contains small solid particles of silicate nature as “contaminants”.

Recently, for the first time in the press, a comparison of the nucleus of Halley's comet with a dirty March snowdrift appeared in the press, in which a mud crust protects the snowdrift from rapid evaporation. Something similar happens in a comet - under the influence of sunlight, the icy component sublimes and in the form of gas streams moves away from the core, which very weakly attracts all objects to itself. These gas flows also carry along solid dust, which forms the comet's dust tails.

The Vega-1 apparatus established that every second 5 - 10 tons of dust are ejected from the core - some of it still remains, covering the ice core with a protective dust crust; Because of this crust, the reflectivity (albedo) of the core is noticeably reduced and the surface temperature of the core turns out to be quite high. Water constantly evaporates from a comet near the Sun, which can explain the presence of a hydrogen corona in comets. In general, the “ice model” of the core was brilliantly confirmed, and from now on it has become a fact instead of a hypothesis. The size of Halley's comet is so small that its nucleus could easily fit on the territory of Moscow inside the ring road. Once again, humanity has become convinced that comets are small bodies in a state of continuous destruction.

Meeting in 1986 was very successful for science, and now we will meet Halley’s Comet only in 2061.

The life of comets is relatively short - even the largest of them can make only a few thousand revolutions around the Sun. After this period, the comet's nucleus completely disintegrates. But such decay occurs gradually, and therefore, throughout the life of the comet, a trail of decay products of its nucleus, resembling a donut, is formed along the entire orbit. That is why, every time we encounter such a “donut,” a large number of “shooting stars”—meteor bodies generated by a disintegrating comet—fly into the earth’s atmosphere. Then they talk about the meeting of our planet with a meteor shower.

Twice a year, in May and October, the Earth passes through a “meteor donut” generated by the nucleus of Comet Halley. In May, meteors fly out from the constellation Aquarius, in October - from the constellation Orion.

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In our solar system, along with the planets and their satellites, there are space objects that are of great interest in the scientific community and popular among ordinary people. Comets rightfully occupy a place of honor in this series. They add brightness and dynamics to the solar system, turning near space into a testing ground for research for a short time. The appearance of these space wanderers in the sky is always accompanied by bright astronomical phenomena that even an amateur astronomer can observe. The most famous space guest is Halley's Comet, a space object that regularly visits near-Earth space.

The last appearance of Comet Halley in our near space occurred in February 1986. She appeared in the sky for a short moment in the constellation Aquarius and quickly disappeared into the halo of the solar disk. During the passage of perihelion in 1986, the space guest was within sight of the Earth and could be observed for a short period. The comet's next visit should take place in 2061. Will the usual schedule for the appearance of the most famous space visitor be disrupted after 76 years, will the comet come to us again in all its beauty and brilliance?

When did Halley's comet become known to man?

The frequency of appearance of known comets in the Solar System does not exceed 200 years. The visits of such guests always caused ambiguous reactions in people, causing concern to some unenlightened people and delighting the scientific fraternity.

For other comets, visits to our solar system are rare. Such objects fly into our near space with a periodicity of more than 200 years. It is not possible to calculate their exact astronomical data due to their rare occurrence. In both cases, humanity has constantly dealt with comets throughout its existence.

For a long time, people were in the dark about the nature of this astrophysical phenomenon. Only at the beginning of the 18th century was it possible to begin a systematic study of these interesting space objects. Halley's Comet, discovered by the English astronomer Edmund Halley, became the first celestial body about which it was possible to obtain reliable information. This became possible due to the fact that this space hulk is clearly visible to the naked eye. Using observational data from his predecessors, Halley was able to identify a space guest who had visited the solar system three times before. According to his calculations, the same comet appeared in the night sky in 1531, 1607 and 1682.

Today, astrophysicists, using the nomenclature of comets and the available information about their parameters, can confidently say that the appearance of Halley’s comet was noted in the earliest sources, approximately in 240 BC. Judging by the descriptions available in Chinese chronicles and manuscripts of the Ancient East, the Earth has already encountered this comet more than 30 times. The merit of Edmund Halley lies in the fact that it was he who was able to calculate the periodicity of the appearance of a cosmic guest and quite accurately predict the next appearance of this celestial body in our night sky. According to him, the next visit was supposed to take place 75 years later, at the end of 1758. As the English scientist expected, in 1758 the comet once again visited our night sky and by March 1759 flew within sight. This was the first predicted astronomical event associated with the existence of comets. From that moment on, our constant celestial guest was named after the famous scientist who discovered this comet.

Based on many years of observations of this object, approximately the timing of its subsequent appearances has been compiled. Despite the fact that, in comparison with the transience of human life, the orbital period of Comet Halley is quite long (74-79 Earth years), scientists always look forward to the next visit of the space wanderer. In the scientific community, it is considered great luck to observe this enchanting flight and the accompanying astrophysical phenomena.

Astrophysical features of the comet

In addition to its fairly frequent appearance, Halley's Comet has some interesting features. This is the only well-studied cosmic body that, at the moment of approaching the Earth, moves with our planet on a collision course. The same parameters are observed in relation to the movement of other planets in our star system. Hence, there are quite wide opportunities for observing the comet, which makes its flight in the opposite direction along a highly elongated elliptical orbit. The eccentricity is 0.967 e and is one of the highest in the Solar System. Only Nereid, a satellite of Neptune, and the dwarf planet Sedna have orbits with such similar parameters.

The elliptical orbit of Comet Halley has the following characteristics:

• the length of the semi-major axis of the orbit is 2.667 billion km;
• at perihelion, the comet moves away from the Sun to a distance of 87.6 million km;
• when Halley's comet passes near the Sun at aphelion, the distance to our star is 5.24 billion km;
• The comet's orbital period according to the Julian calendar averages 75 years;
• The speed of Halley's comet when moving in orbit is 45 km/s.

All of the above data about the comet became known as a result of observations made over the past 100 years, from 1910 to 1986. Thanks to the highly elongated orbit, our guest flies past us at a huge oncoming speed - 70 kilometers per second, which is an absolute record among the space objects of our solar system. Halley's Comet of 1986 provided the scientific community with a lot of detailed information about its structure and physical characteristics. All data obtained was obtained through direct contact of automatic probes with a celestial object. Research was carried out using the Vega-1 and Vega-2 spacecraft, specially launched for a close acquaintance with the space guest.

Automatic probes made it possible not only to obtain information about the physical parameters of the nucleus, but also to study in detail the shell of the celestial body and get an idea of ​​​​what the tail of Halley's comet is.

In terms of its physical parameters, the comet turned out to be not as large as previously thought. The size of the irregularly shaped cosmic body is 15x8 km. The greatest length is 15 km. with a width of 8 km. The comet's mass is 2.2 x 1024 kg. In terms of its size, this celestial body can be equated to medium-sized asteroids wandering in the space of our solar system. The density of the space wanderer is 600 kg/m3. For comparison, the density of water in the liquid state is 1000 kg/m3. Data on the density of a comet's nucleus vary depending on its age. The latest data are the result of observations taken during the comet's last visit in 1986. It is not a fact that in 2061, when the next arrival of a celestial body is expected, its density will be the same. The comet continually loses weight, disintegrates, and may eventually disappear.

Like all space objects, Halley's Comet has an albedo of 0.04, comparable to the albedo of charcoal. In other words, the comet's nucleus is a fairly dark space object with a weak surface reflectivity. Almost no sunlight is reflected from the comet's surface. It becomes visible only due to its rapid movement, which is accompanied by a bright and spectacular effect.

During its flight through the expanses of the solar system, the comet is accompanied by the Aquarids and Orionids meteor showers. These astronomical phenomena are natural products of the destruction of the comet's body. The intensity of both phenomena can increase with each subsequent passage of the comet.

Versions about the origin of Halley's comet

In accordance with the accepted classification, our most popular space guest is a short-period comet. These celestial bodies are characterized by a low orbital inclination relative to the ecliptic axis (only 10 degrees) and a short orbital period. As a rule, such comets belong to the family of Jupiter comets. Against the background of these space objects, Halley's comet, like other space objects of the same type, stands out strongly for its astrophysical parameters. As a result, such objects were classified as a separate, Halley type. At the moment, scientists could only detect 54 comets of the same type as Halley’s comet, which in one way or another visit near-Earth space throughout the existence of the Solar System.

There is an assumption that such celestial bodies were previously long-period comets and moved to another class only due to the influence of the gravitational force of the giant planets: Jupiter, Saturn, Uranus and Neptune. In this case, our current permanent guest could have formed in the Oort cloud - the outer region of our solar system. There is also a version about a different origin of Halley's comet. The formation of comets is allowed in the border region of the Solar system, where trans-Neptunian objects are located. In many astrophysical parameters, small bodies in this region are very similar to Halley's comet. We are talking about the retrograde orbit of objects, strongly reminiscent of the orbit of our cosmic guest.

Preliminary calculations have shown that the celestial body, which flies to us every 76 years, has existed for more than 16,000 years. At least the comet has been moving in its current orbit for quite a long time. It is not possible to say whether the orbit was the same for 100-200 thousand years. A flying comet is constantly influenced not only by the forces of gravity. Due to its nature, this object is highly susceptible to mechanical influence, which in turn causes a reactive effect. For example, when a comet is at aphelion, the sun's rays heat its surface. In the process of heating the surface of the core, sublimating gas flows arise, acting like rocket engines. At this moment, fluctuations in the comet's orbit occur, affecting deviations in the orbital period. These deviations are clearly visible already at perihelion and can last 3-4 days.

Soviet robotic spacecraft and European Space Agency probes narrowly missed the target on their voyage to Halley's Comet in 1986. Under terrestrial conditions, it turned out to be impossible to predict and calculate possible deviations in the comet's orbital period, which caused vibrations of the celestial body in orbit. This fact confirmed the scientists' version that the orbital period of Halley's Comet may change in the future. In this aspect, the composition and structure of comets become interesting. The preliminary version that these are huge blocks of space ice is refuted by the long existence of comets that did not disappear or evaporate in outer space.

Composition and structure of the comet

The nucleus of Halley's comet was studied at close range for the first time by robotic space probes. If previously a person could observe our guest only through a telescope, looking at her at a distance of 28 06 a. That is, now the pictures were taken from a minimum distance, just over 8000 km.

In fact, it turned out that the comet's nucleus is relatively small in size and resembles an ordinary potato tuber in appearance. Examining the density of the core, it becomes clear that this cosmic body is not a monolith, but is a pile of debris of cosmic origin, closely connected by gravitational forces into a single structure. A giant block of stone does not just fly in outer space, tumbling in different directions. The comet has a rotation, which, according to various sources, lasts 4-7 days. Moreover, the rotation is directed in the direction of the comet’s orbital movement. Judging by the photographs, the core has a complex topography, with depressions and hills. A crater of cosmic origin was even discovered on the surface of the comet. Even despite the small amount of information obtained from the images, it can be assumed that the comet's nucleus is a large fragment of another large cosmic body that once existed in the Oort cloud.

The comet was first photographed in 1910. At the same time, data from a spectral analysis of the composition of our guest’s coma were obtained. As it turned out, during the flight, as it approaches the Sun, volatile substances, represented by frozen gases, begin to evaporate from the heated surface of the celestial body. Nitrogen, methane and carbon monoxide vapors are added to water vapor. The intensity of emission and evaporation leads to the fact that the size of the coma of Halley's comet exceeds the size of the comet itself by thousands of times - 100 thousand km. versus 11 km of the average size. Along with the evaporation of volatile gases, dust particles and small fragments of the comet's nucleus are released. Atoms and molecules of volatile gases refract sunlight, producing a fluorescent effect. Dust and large fragments scatter reflected sunlight into space. As a result of the ongoing processes, the coma of Comet Halley is the brightest element of this celestial body, ensuring its good visibility.

Don’t forget about the comet’s tail, which has a special shape and is its trademark.

There are three types of comet tails to distinguish:

• type I comet tail (ionic);
• comet tail type II;
• Type III tail.

Under the influence of solar wind and radiation, the substance is ionized, creating a coma. Charged ions under the pressure of the solar wind are pulled into a long tail, the length of which exceeds hundreds of millions of km. The slightest fluctuations in the solar wind or a decrease in the intensity of solar radiation leads to partial breakage of the tail. Often such processes can lead to the complete disappearance of the tail of a space wanderer. Astronomers observed this phenomenon with Halley's comet in 1910. Due to the huge difference in the speed of movement of the charged particles that make up the comet's tail and the orbital speed of the celestial body, the direction of development of the comet's tail is located strictly in the opposite direction from the Sun.

As for solid fragments, cometary dust, the influence of the solar wind is not so significant, so the dust spreads at a speed resulting from a combination of the acceleration imparted to the particles by the pressure of the solar wind and the initial orbital speed of the comet. As a result, the dust tails lag significantly behind the ion tail, forming separate type II and III tails, directed at an angle to the direction of the comet's orbit.

In terms of intensity and frequency of emission, comet dust tails are a short-term phenomenon. While the comet's ion tail fluoresces and produces a violet glow, type II and III dust tails have a reddish tint. Our guest is characterized by the presence of tails of all three types. Astronomers are quite familiar with the first two, while the tail of the third type was noticed only in 1835. On its last visit, Halley's comet rewarded astronomers with the opportunity to observe two tails: type 1 and type 2.

Analysis of the behavior of Comet Halley

Judging by the observations made during the comet's last visit, the celestial body is a fairly active space object. The side of the comet facing the Sun at a certain moment is a boiling source. Temperatures on the surface of the comet facing the Sun range from 30 to 130 degrees Celsius, while the rest of the comet's core drops to below 100 degrees. This discrepancy in temperature readings suggests that only a small part of the comet's nucleus has a high albedo and can become quite hot. The remaining 70-80% of its surface is covered with a dark substance and absorbs sunlight.

Such research has suggested that our bright and dazzling guest is actually a lump of dirt mixed with cosmic snow. The bulk of cosmic gases is water vapor (more than 80%). The remaining 17% is represented by carbon monoxide, particles of methane, nitrogen and ammonia. Only 3-4% comes from carbon dioxide.

As for comet dust, it mainly consists of carbon-nitrogen-oxygen compounds and silicates, which form the basis of the terrestrial planets. The study of the composition of water vapor released by the comet put an end to the theory of the cometary origin of the Earth's oceans. The amount of deuterium and hydrogen in the nucleus of Halley's comet turned out to be significantly greater than their amount in the composition of the earth's water.

If we talk about how much material this lump of dirt and snow has for life, then here you can look at Halley's comet from different angles. Scientists' calculations, based on data on 46 appearances of the comet, indicate that the life of a celestial body is chaotic and constantly changing depending on external conditions. In other words, throughout its existence the comet remains in a state of dynamic chaos.

The estimated lifespan of Halley's Comet is estimated at 7-10 billion years. Having calculated the volume of matter lost during the last visit to our near-Earth space, scientists concluded that the comet's nucleus has already lost up to 80% of its original mass. It can be assumed that our guest is now in old age and in a few thousand years will disintegrate into small fragments. The finale of this brightest life can happen within the solar system, in our sight, or, conversely, take place in the outskirts of our common home.

Finally

The last visit of Halley's Comet, which took place in 1986 and was expected for so many years, was a great disappointment for many. The main reason for mass disappointment was the lack of opportunity to observe a celestial body in the northern hemisphere. All preparations for the upcoming event went down the drain. On top of that, the observation period of the comet turned out to be very short. This has resulted in few observations being made by scientists around the world. A few days later the comet disappeared behind the solar disk. The next meeting with the space guest has been postponed for 76 years.