Observing these changes, we can determine the physical conditions in the space of the solar system.

Unlike planets that revolve around the Sun in a counterclockwise direction (as viewed from the Earth’s north pole), Halley’s Comet moves clockwise, making a complete rotation in an average of 75-76 years.

Passing near the Sun, the comet approaches it at a minimum distance of about 900 million kilometers. At this point, it is at a point (so-called perihelion), located between the orbits of Mercury and Venus.

In the twentieth century, Halley’s Comet approached the Earth in 1909-1911. In those days, in preparation for the next meeting with the comet, scientists estimated that on the night of 19 to 20 May 1910, the Earth will pass through its tail. This message caused panic around the world. The "cosmic rendezvous" of the two celestial bodies was awaited by many with great fear. The fact is that the comet tails contain the poisonous gas cyanide. And literally at every step you could hear talk about the coming world catastrophe, that the poisonous gases of the comet’s tail will have a detrimental effect on all life on Earth.

Of course, astronomers that comet tails are extremely sparse and can not pose a real danger to the inhabitants of the Earth, which are also protected by the atmosphere. And yet "comet fears" have spread to almost the whole world. In addition, religious people associated the upcoming astronomical event with the notion of a "terrible judgment" about the supposed future doom of the world, which was repeatedly predicted by various religious prophets. Prayers were held in the streets of many cities, Christian clerics did not have time to confess to all comers, and Muslim mullahs called on the faithful to fast and pray.

In fact, around May 18, the Earth passed through the tail of Halley’s Comet, but no one even noticed. Moreover, the special measurements did not "reveal any changes in the normal chemical composition of the Earth’s air envelope. This was another indication of the extreme rarefaction of comet tails.

Interestingly, in the vast majority of cases, comets are relatively short-lived celestial bodies. Passing near large planets, they experience their strong gravity and under its action are gradually destroyed. Apparently, Halley’s Comet is an exception to this rule. Evidence of its appearance can be traced to some data up to 240 BC, ie for more than two millennia. There is no other comet in the memory of mankind, the appearance of which could be traced so far back in time.

Most likely, the "survivability" of Halley’s comet is to some extent explained by the fact that the plane of its orbit is markedly inclined to the plane in which the planets move. In addition, the reverse direction of its motion compared to the planets is of considerable importance. As a result, it quickly "diverges" from the "oncoming" planets in parallel courses and is exposed to their destructive gravity only for relatively short periods of time. In addition, due to the large period of rotation of Halley’s comet, its approach to the planets are relatively rare. However, perturbations of Halley’s Comet’s orbit still occur and this affects the period of its rotation: it ranges from 74 to 79 years.

At one time, astronomers learned by the law of gravity to calculate the orbits of comets as accurately as possible, taking into account all possible influences from other bodies in the solar system. However, the "heavenly guests" for some reason stubbornly refused to follow the "schedule" of their movement calculated by scientists. It became clear that the motion of comets is influenced not only by gravity, but also by some other forces that have a different physical nature.

The nature of these forces was clarified only in the middle of this century, when astronomers came to the conclusion that they are reactive forces. The gases emitted by cometary nuclei create a reactive effect, although relatively small, but sufficient to have some effect on the motion of comets.

Thus, it can be argued that cometary nuclei consist of frozen gases – more precisely, of dirty ice or snow. This is mainly ordinary water ice, as well as ice from carbon dioxide and carbon monoxide. About one third of the mass of cometary nuclei are various stony substances.

When a comet approaches the Sun at a distance of about 600-700 million kilometers, under the influence of solar radiation, the gases contained in its core, begin to emit, carrying out rocky and ice particles, which immediately evaporate, enveloping the write your lab report nucleus with a misty shell – comet atmosphere.

This shell is continuously dissipated in airless space, while being replenished with gases emitted from the nucleus. Under the action of the solar wind – particles flying from the Sun – and the light pressure of the sun’s rays, comet gases and solid particles fly in the opposite direction to the Sun, forming a luminous tail. When a comet moves away from the Sun, its tail gradually dissipates in space.

Comets are extremely interesting space objects for science. Moving away at great distances from the Sun, 7-10 times the distance of the Earth from our daylight, comets are exposed to physical influences that change their state. Observing these changes, we can determine the physical conditions in the space of the solar system.

Thus, comets can be a kind of probes created by nature, which provide an opportunity to obtain unique information about the physical processes occurring in interplanetary space.

In addition, of great scientific interest is the study of the structure and composition of the cometary nuclei, because according to some assumptions, the material of the cometary nuclei is the primordial substance from which the planets of the solar system were formed in the distant past.

During the next convergence of Halley’s comet with the Sun and the Earth in 1985-1986 p. a unique operation was carried out – the project "Vega" during which the study of this comet by spacecraft.

Scientists from socialist countries, as well as France, Austria and Germany, took part in the project together with Soviet scientists.

At the end of December 1984, two Soviet interplanetary stations were launched from one of the Soviet spaceports at intervals of several days. They first delivered research equipment to the planet Venus, and then continued the flight to get closer to Comet Halley.

In March 1986, both stations passed near the nucleus of Halley’s Comet, making a large complex of observations, followed by the Giotto station of the European Space Agency and two Japanese stations "Pioneer-A" and "Pioneer".

Analysis of the obtained data showed that the nucleus of Halley’s comet, apparently, was a monolithic body of irregular shape, measuring approximately 7.5 X 8.2 X XI6 km. It is covered with a refractory dark crust, about 1 cm thick, through which water vapor and gases break through from time to time. The surface temperature of this crust is 300-400 K. As for the temperature of the core, it turned out to be equal to 100 degrees Celsius. The core rotates around its axis, making a complete rotation in 50-56 hours.

Space research has apparently confirmed the notion of the ice nature of space nuclei, although a number of questions regarding the structure of these objects remain unclear and are the subject of scientific debate.

It has been repeatedly suggested that comets may be a kind of carrier of life. Therefore, of particular interest was the answer to the question of the presence of organic matter in the nucleus of Halley’s comet.

As a result of processing the results of studies of the composition of comet dust performed on board the spacecraft "Vega-1" were found organic molecules, including those that contained carbon and hydrogen; carbon, nitrogen and hydrogen; carbon, oxygen and hydrogen, etc. Nucleic acid molecules have not been detected, but it is possible that, entering the warm aqueous medium, the organic molecules contained in the comet may form these acids.

Methodical considerations. When presenting material on "extraordinary" celestial phenomena, special attention should be paid to the fact that these phenomena are based on the same natural laws that govern the course of ordinary "everyday" phenomena.

Thus, the eclipses of the Moon and the Sun are the result of the motion of the Moon and the Earth according to the same Kepler laws that control the motion of the planets around the Sun.

The motion of comets is subject to the law of gravity, the manifestations of which we encounter at every turn. By the way, Kepler’s laws can be derived purely mathematically from the law of universal gravitation, namely Kepler’s laws describe the motion of periodic comets.

Meteor phenomena are due to the same physical laws, according to which the destroyed and "burned" artificial satellites of the Earth, which have expired, and spacecraft, which enter with supersonic speeds into the dense layers of the Earth’s atmosphere.

It should also be emphasized that with the action of patterns that determine the occurrence of "extraordinary" phenomena, we often encounter in everyday life and even use them in our practice.

You can give such an example in connection with the "bloody" color of the moon during lunar eclipses. Everyone is well aware of the prohibitory red "stop signals" of street and railway traffic lights, red-orange signal lights of airports, red and orange lights of lighthouses. It is worth mentioning the bright orange costumes of astronauts and overalls of road workers. In all these cases, the red and orange colors are chosen not by chance: if the red and orange rays are less than others scattered in the air, the signal lights and objects of such colors will be clearly visible at a great distance.

Interestingly, for example, according to road accident statistics, red and orange cars are less likely to be involved in an accident than cars of other colors, such as gray, blue or green. This is due to the fact that red and orange cars drivers of oncoming cars notice from afar.

In connection with the question of "extraordinary" celestial phenomena, one should pay attention to another circumstance. Religious faith actually puts a person in psychological dependence on divine, supernatural forces. A person prays to them, makes sacrifices – direct or indirect, makes a request, correlates his behavior with their expected reaction to certain actions. In other words, the believer "interacts" with supernatural forces.