Astronomy is perhaps the most interesting science of all school subjects. Oh, what a pity that she has so few hours to study.

The word "astronomy" comes from the Greek: astron - star and nomos - law, - this is the science of the structure and development of cosmic bodies, systems and the universe as a whole.

Astronomy is the oldest science. The birth of astronomy was associated with the rejection of the geocentric system of the world (developed by Ptolemy, in the 2nd century) and its replacement heliocentric system(authored by Nicolaus Copernicus, mid-16th century), with the start of telescopic research celestial bodies(Galileo Galilei, early 17th century) and the discovery of the law gravity(Isaac Newton, late 17th century).

The 18th-19th centuries were for astronomy a period of accumulation of data on the solar system, the Galaxy and the physical nature of stars, the Sun, planets and other cosmic bodies.

Extragalactic astronomy began to develop in the 20th century. The study of the spectra of galaxies allowed E. Hubble (1929) to detect the general expansion of the Universe, predicted by A. A. Friedman (1922) on the basis of the theory of gravity created by A. Einstein in 1915-16. Creation of optical and radio telescopes with high resolution, the use of rockets and artificial satellites Earth for exoatmospheric astronomical observations led to the discovery of a number of new types of cosmic bodies: radio galaxies, quasars, pulsars, X-ray sources, etc. The foundations of the theory of stellar evolution and cosmogony were developed solar system. The greatest achievement of astrophysics of the 20th century was relativistic cosmology - the theory of the evolution of the universe as a whole.

The science of astronomy consists of the following sections:

• Spherical astronomy- branch of astronomy that develops mathematical methods solving problems related to the study of the apparent location and movement of cosmic bodies in the celestial sphere.
• Practical astronomy- the doctrine of astronomical instruments and methods for determining time from astronomical observations, geographical coordinates and azimuth directions.
• Astrophysics- a branch of astronomy that studies the physical state and chemical composition of celestial bodies and their systems, interstellar and intergalactic media, as well as the processes occurring in them. The main sections of astrophysics:
  • physics of planets and their satellites
  • solar physics
  • physics of stellar atmospheres
  • interstellar medium
  • theory internal structure stars and their evolution
• Celestial mechanics- a branch of astronomy that studies the movements of the bodies of the solar system in their common gravitational field. The problems of celestial mechanics include the consideration of general questions of the motion of celestial bodies in a gravitational field and the motion of specific objects (planets, artificial Earth satellites, etc.); determination of the values ​​of astronomical constants; composing ephemeris.
• stellar astronomy- a branch of astronomy that studies the general laws of the structure, composition, dynamics and evolution of stellar systems (clusters and galaxies).
• extragalactic astronomy- a branch of astronomy that studies cosmic bodies (stars, galaxies, quasars, etc.) located outside our star system - the Galaxy.
• Cosmogony- a branch of astronomy that studies the origin and development of cosmic bodies and their systems (planets and the solar system as a whole, stars, galaxies).
• Cosmology- the physical doctrine of the Universe as a whole, based on the results of the study of the most common properties the part of the universe that is available for astronomical observation. The general conclusions of cosmology are of great general scientific and philosophical significance. In modern cosmology, the most common model of the hot Universe, according to which in the expanding Universe at an early stage of development, matter and radiation had a very high temperature and density. The expansion led to their gradual cooling, the formation of atoms, and then (as a result of gravitational condensation) - protogalaxies, galaxies, stars and other cosmic bodies.

The science that studies the Universe and is one of the most ancient among mankind is astronomy. This word consists of two Greek words: "nomos" - "law", and "astro" - "luminary, star". Collectively, this term can be translated as "the law of the stars." Astronomy is the whole millennia of observations of the sky, when a variety of knowledge is accumulated. It should be noted that in comparison with other sciences, the level of this science was extremely high already in antiquity.

Then and now

We know the names of the constellations invariably the same for many tens of centuries. Our distant ancestors knew them all, they were able to calculate the sunrise and sunset, planets, the Moon, all the largest stars long before our era. Moreover, scientists already then knew how to predict solar and lunar eclipses. Astronomy is the main science in the life of ancient man. Star hunters found their way home, sailors navigated their ships through the open ocean by the stars. All agricultural work was associated with the established cycle of seasons, time was calculated from the luminaries and calendars were drawn up. Even the fate of astrologers predicted by the stars.

Now, many of the above need has disappeared. The course of the ships and the floods of the rivers no longer need to be calculated by the hourglass, because all kinds of technical means have appeared. However, astronomy is a science that cannot have an end in its development. And now all astronautics is based on its foundations, with the help of this science, mankind uses communication systems, television and observes the Earth from space. Astronomy and mathematics, astronomy and physics are now closely connected, they have common methods of cognition that are widely used.

Two astronomy

The essence of astronomy in antiquity is observation. In this science, experiments are impossible, as in physics or chemistry, since the objects of study are inaccessible to people. But the importance of astronomy in human life is very great even today. All information about celestial bodies is now obtained from the received electromagnetic radiation. But in the last few decades, scientists have been able to study some celestial objects directly - automatic stations probe the atmosphere of nearby planets, their soil is being studied.

It was this fact that divided astronomy into two main parts - theoretical and observational. The latter aims to obtain data from observations of celestial bodies, which are then analyzed using physics and its basic laws. And theoretic astronomers develop computer, mathematical and analytical models with which they describe astronomical phenomena and objects. Is it necessary to say that the significance of astronomy as a science for humanity is simply enormous? After all, these two branches do not exist separately on their own, they complement each other. The theory seeks explanations based on the results of observations, and observers confirm or not all hypotheses and theoretical conclusions.

Astronomy as a philosophical science

The definition of the science of "astronomy" appeared in antiquity and lives happily in our days. This is the study of the fundamental laws of nature of our world, which is closely connected with the great cosmos. That is why at first astronomy was interpreted as a philosophical science. With its help, one's own world is known through the knowledge of celestial objects - stars, planets, comets, galaxies, as well as those phenomena that now and then occur outside the earth's atmosphere - the radiance of the Sun, solar wind, cosmic radiation, and so on.

Even the lexical meaning of the word "astronomy" speaks of the same: the law of the stars also applies here, on Earth, since it is part of a vast cosmos that develops according to a single law. It is thanks to him that evolution, physics, chemistry, meteorology and any other science were presented to mankind. Everything in the world develops through a certain movement of celestial bodies: galaxies form and develop, stars die and flare up again. It should always be remembered where any other science began. It is a great misfortune that there is no astronomy at school now. This knowledge and understanding of the vastness and value of the world cannot be replaced by anything.

The twentieth century

Thus, observational astronomy and theoretical astrophysics constituted professional science. More and more new instruments for studying space were tirelessly created, plus the telescope already invented in time immemorial. The information was collected and processed, then introduced by theoretical astrophysicists into the models they created - analytical or computer.

The meaning of the word "astronomy" has gained immense weight in all areas of human science, since even the famous theory of relativity is built from the fundamental laws of astronomical physics. And, interestingly, most of the discoveries are made by amateur astronomers. This is one of the very few sciences where people outside of it can participate in observations and collect data for it.

Astronomy and astrology

Modern schoolchildren (and even students) quite often confuse science and belief system, yet the lack of appropriate lessons in school programs. Astrology has long been considered a pseudoscience, which claims that any human business, even the smallest, depends on the position of the stars. Of course, these two names come from the same root, but the systems of cognition for both are absolutely opposite.

Astronomy, on the other hand, allowed man to make a huge leap in understanding the laws of the universe. This science is unknowable to the end, there will always be more questions to which there is no answer than those to which the answer is found. No matter how many devices are built in space and on Earth, no matter how many world-stunning discoveries are made, this is only a drop in the ocean of knowledge. AT this moment we still cannot say for sure either the origin of stellar mass in its entire spectrum, or positively or negatively answer the question of the existence of other life in the Universe. The Fermi paradox is not explained. The nature of the darkness is not clear. We do not know anything about the time period of the existence of the Universe, as well as about the specific purpose of its existence.

Astronomy and history

Having learned to distinguish between stars and planets, ancient astronomers tied this knowledge to transcendence, identifying all known celestial bodies with spirits and gods. Then a dead-end branch of science appeared - astrology, since the movement of all space objects was firmly tied to purely earthly phenomena - the change of seasons, rains, droughts.

Then the Magi appeared (priests, priests and similar cult workers), who were considered professional astronomers. Many ancient buildings - Chinese temples or Stonehenge, for example, clearly combined two functions - astronomical and religious.

East and West

So many useful things were done that the ancient knowledge could well serve as the basis of science, which is most flourishing today. According to the movement of the luminaries, calendars were lined up - the ancient Roman one is still alive. In China, in 2300 BC, the astronomical observatory she is in the picture.

Oracles in China have kept drawings of eclipses and the appearance of new stars for four thousand years. From the sixth century BC there are detailed astronomical records in China. And in Europe, this whole boom began only in the seventeenth century AD. The Chinese, on the other hand, have been absolutely correct in predicting the appearance of comets for many thousands of years. In the same place, about six thousand years ago, the first star atlas was made.

Ancient Greece and the Arab world

Europe in the Middle Ages completely and completely stopped all the development of science in its territories, even the Greek discoveries, which turned out to be true in many respects and made many valuable contributions to the science of astronomy, were anathematized. That is why classical antiquity has come down to our days in a very meager number of summary records and compilations.

But astronomy flourished in the Arab countries, and the priests of the most distant parishes of Christians two thousand years ago were able to calculate the exact date of Easter along the course of the stars. Arabs translated the works of astronomers in many Ancient Greece, and it was there that the descendants found the manuscripts in the depths of the surviving libraries. Observatories have been built in Arab countries since the ninth century AD. In Persia, the poet and scholar Omar Khayyam compared a huge number of tables and reformed the calendar, making it more accurate than the Julian and closer to the Gregorian. In this he was helped by constant observations of celestial bodies.

Celestial mechanics

Universal gravity became known to the world thanks to Isaac Newton. Today's schoolchildren heard this name only in connection with the three laws of physics. They are unaware that these laws are closely related to celestial mechanics, since there are no astronomy lessons at school.

It will be a great happiness to know that this essential item is back in the ranks. Scientific secretary from the Institute space research Russian Academy Sciences Alexander Zakharov is sure that the shortage of astronomy teachers existing in the country can be replenished quickly if this discipline returns to academic plan. The director of the planetarium in Novosibirsk, Sergei Maslikov, is sure that the planned return of astronomy to school can hardly take place earlier than in five or six years. However, the Minister of Education and Science of the Russian Federation Olga Vasilyeva says that this hour a week for studying the subject of astronomy should be returned to schoolchildren as soon as possible.

Astronomy. What is astronomy?

Astronomy is the science of the location, structure, properties, origin, movement and development of cosmic bodies (stars, planets, meteorites, etc.) of the systems they form ((star clusters, galaxies, etc.) and the entire Universe as a whole.

As a science, astronomy is based primarily on observations. Unlike physicists, astronomers are deprived of the opportunity to experiment. Almost all information about celestial bodies is brought to us by electromagnetic radiation. Only in the last forty years have individual worlds been studied directly: to probe the atmospheres of planets, to study the lunar and Martian soil.

Astronomy is closely connected with other sciences, primarily with physics and mathematics, the methods of which are widely used in it. But astronomy is also an indispensable testing ground on which many physical theories are tested. Space is the only place where matter exists at temperatures of hundreds of millions of degrees and almost at absolute zero, in the void of vacuum and in neutron stars. Recently, the achievements of astronomy have been used in geology and biology, geography and history. What does astronomy study

What does astronomy study

Astronomy studies the Sun and stars, planets and their satellites, comets and meteoroids, nebulae, star systems and the matter that fills the space between stars and planets, in whatever state this matter may be. By studying the structure and development of celestial bodies, their position and movement in space, astronomy ultimately gives us an idea of ​​the structure and development of the universe as a whole. The word "astronomy" comes from two Greek words: "astron" - star, luminary and "nomos" - law. When studying celestial bodies, astronomy sets itself three main tasks that require a consistent solution:

1. The study of the visible, and then the actual positions and movements of celestial bodies in space, determining their size and shape.

2. The study of the physical structure of celestial bodies, i.e. study of the chemical composition and physical conditions (density, temperature, etc.) on the surface and in the depths of celestial bodies.

3. Solving the problems of origin and development, i.e. possible further fate of individual celestial bodies and their systems.

Questions of the first problem are solved by means of long-term observations, which began in ancient times, as well as on the basis of the laws of mechanics, which have been known for about 300 years. Therefore, in this area of ​​astronomy we have the richest information, especially for celestial bodies relatively close to the Earth.

We know much less about the physical structure of celestial bodies. The solution of some questions belonging to the second task first became possible a little more than a hundred years ago, and the main problems - only in recent years.

Division of Astronomy

Modern astronomy is divided into a number of separate sections that are closely related to each other, and such a division of astronomy is, in a certain sense, conditional. The main branches of astronomy are:

1. Astrometry - the science of measuring space and time. It consists of: a) spherical astronomy, which develops mathematical methods for determining the apparent positions and movements of celestial bodies using various coordinate systems, as well as the theory of regular changes in the coordinates of luminaries over time; b) fundamental astrometry, whose tasks are to determine the coordinates of celestial bodies from observations, compile catalogs of star positions and determine the numerical values ​​of the most important astronomical constants, i.e. quantities that make it possible to take into account the regular changes in the coordinates of the luminaries; c) practical astronomy, which sets out methods for determining geographic coordinates, azimuths of directions, exact time and describes the tools used in this.

2. Theoretical astronomy provides methods for determining the orbits of celestial bodies from their apparent positions and methods for calculating the ephemeris (apparent positions) of celestial bodies from known elements their orbits (inverse problem).

3. Celestial mechanics studies the laws of motion of celestial bodies under the influence of universal gravitational forces, determines the masses and shape of celestial bodies and the stability of their systems. These three branches basically solve the first problem of astronomy and are often referred to as classical astronomy.

4. Astrophysics studies the structure, physical properties and chemical composition of celestial objects. It is divided into: a) practical astrophysics, in which practical methods of astrophysical research and related instruments and instruments are developed and applied; b) theoretical astrophysics, in which, on the basis of the laws of physics, explanations are given for the observed physical phenomena. A number of branches of astrophysics are distinguished by specific research methods. They will be discussed in § 101,

5. Stellar astronomy studies the regularities of the spatial distribution and motion of stars, stellar systems and interstellar matter, taking into account their physical features. In these two sections, questions of the second problem of astronomy are mainly solved.

6. Cosmogony considers the origin and evolution of celestial bodies, including our Earth.

7. Cosmology studies the general laws of the structure and development of the Universe.

Based on all the knowledge gained about celestial bodies, the last two sections of astronomy solve its third problem.

Story

Astronomy is the most ancient among natural sciences. It was highly developed by the Babylonians and Greeks - much more than physics, chemistry and technology. In antiquity and the Middle Ages, not only purely scientific curiosity prompted calculations, copying, corrections of astronomical tables, but above all the fact that they were necessary for astrology. By investing large sums in the construction of observatories and precision instruments, those in power expected a return not only in the form of the glory of the patrons of science, but also in the form of astrological predictions. Only a very small number of books of those times have survived, indicating a purely theoretical interest of scientists in astronomy; most books contain neither observations nor theory, but only tables and rules for their use. One of the few exceptions is Ptolemy's Almagest, who, however, also wrote the astrological manual Tetrabiblos.

The first records of astronomical observations, the authenticity of which is beyond doubt, date back to the 8th century. BC. However, it is known that as early as 3 thousand years BC. e. Egyptian priests noticed that the floods of the Nile, which regulated the economic life of the country, came soon after the brightest of the stars, Sirius, appeared in the east before sunrise, which had been hidden in the rays of the Sun for about two months. From these observations, the Egyptian priests determined the length of the tropical year quite accurately.

In ancient China for 2 thousand years BC. the apparent movements of the sun and moon were so well understood that Chinese astronomers could predict the onset of solar and lunar eclipses. Astronomy, like all other sciences, arose from the practical needs of man. The nomadic tribes of primitive society needed to navigate their travels, and they learned to do this by the sun, moon and stars. The primitive farmer had to take into account the onset of the various seasons of the year during field work, and he noticed that the change of seasons is associated with the midday height of the Sun, with the appearance of certain stars in the night sky. Further development human society caused the need for time measurement and chronology (calendar compiling).

All this could be given and was given by observations of the movement of the heavenly bodies, which were carried out at the beginning without any instruments, were not very accurate, but fully satisfied the practical needs of that time. From such observations, a spider about celestial bodies arose - astronomy.

With the development of human society, astronomy faced more and more new tasks, the solution of which required more advanced methods of observation and more accurate calculation methods. Gradually, the simplest astronomical instruments began to be created and mathematical methods for processing observations were developed.

In ancient Greece, astronomy was already one of the most developed sciences. To explain the apparent movements of the planets, Greek astronomers, the largest of them Hipparchus (II century BC), created the geometric theory of epicycles, which formed the basis of the geocentric system of the world of Ptolemy (II century AD). Being fundamentally wrong, Ptolemy's system nevertheless made it possible to predict the approximate positions of the planets in the sky and therefore satisfied, to a certain extent, practical needs for several centuries.

The system of the world of Ptolemy completes the stage of development of ancient Greek astronomy. The development of feudalism and the spread of the Christian religion led to a significant decline in the natural sciences, and the development of astronomy in Europe slowed down for many centuries. In the era of the gloomy Middle Ages, astronomers were engaged only in observations of the apparent movements of the planets and the coordination of these observations with the accepted geocentric system of Ptolemy.

Astronomy received rational development during this period only among the Arabs and the peoples of Central Asia and the Caucasus, in the works of outstanding astronomers of that time - Al-Battani (850-929), Biruni (973-1048), Ulugbek (1394-1449). .) and others. During the period of the emergence and formation of capitalism in Europe, which replaced the feudal society, the further development of astronomy began. It developed especially rapidly in the era of great geographical discoveries (XV-XVI centuries). nascent new class the bourgeoisie was interested in the exploitation of new lands and equipped numerous expeditions to discover them. But long journeys across the ocean required more accurate and simpler methods of orientation and timing than those that the Ptolemaic system could provide. The development of trade and navigation urgently required the improvement of astronomical knowledge and, in particular, the theory of planetary motion. The development of productive forces and the requirements of practice, on the one hand, and the accumulated observational material, on the other, prepared the ground for a revolution in astronomy, which was produced by the great Polish scientist Nicolaus Copernicus (1473-1543), who developed his heliocentric system of the world, published in the year his death.

The teachings of Copernicus marked the beginning of a new stage in the development of astronomy. Kepler in 1609-1618. the laws of motion of the planets were discovered, and in 1687 Newton published the law of universal gravitation.

The new astronomy gained the opportunity to study not only the visible, but also the actual motions of celestial bodies. Her numerous and brilliant successes in this area were crowned in the middle of the 19th century. the discovery of the planet Neptune, and in our time - the calculation of the orbits of artificial celestial bodies.

The next, very important stage in the development of astronomy began relatively recently, from the middle of the 19th century, when spectral analysis arose and photography began to be used in astronomy. These methods enabled astronomers to begin studying the physical nature of celestial bodies and significantly expand the boundaries of the space under study. Astrophysics arose, which received especially great development in the 20th century. and continues to grow rapidly today. In the 40s. 20th century radio astronomy began to develop, and in 1957 the foundation was laid for qualitatively new research methods based on the use of artificial celestial bodies, which later led to the emergence of a virtually new branch of astrophysics - x-ray astronomy (see § 160).

The significance of these achievements in astronomy can hardly be overestimated. Launch of artificial earth satellites. (1957, USSR), space stations (1959, USSR), the first manned space flights (1961, USSR), the first landing of people on the moon (1969, USA), are epoch-making events for all mankind . They were followed by the delivery of lunar soil to Earth, the landing of descent vehicles on the surfaces of Venus and Mars, and the sending of automatic interplanetary stations to the more distant planets of the solar system.

Similar abstracts:

Spectral analysis is a method that provides valuable and most diverse information about celestial bodies. It allows you to establish from the analysis of light the qualitative and quantitative chemical composition of the luminary, its temperature.

The solar system includes nine large planets, which, with their 57 satellites, revolve around a massive star in elliptical orbits. According to their size and mass, the planets can be divided into two groups.

About ten years after Bruno's death, the news spread around the world that Galileo Galilei had made amazing and new astronomical discoveries.

Everything repeats in the sky above us: every night the stars rise and set, the moon phases change, the Sun finds its way between the stars. Most likely, it was these regularities that were discovered by the first astronomers sitting by the primitive fire.

HISTORICAL INFORMATION ON THE DEVELOPMENT OF TRIGONOMETRY The need for solving triangles first arose in astronomy: and for a long time trigonometry developed as one of the departments of astronomy.

Paradoxically, today, in the era of lasers and satellites, in the most technically advanced society in the history of mankind, astrology flourishes - the prediction of the fate of an object by the location of stars and planets at the time of its birth.

So many artificial celestial bodies revolve around the Earth that during the entire time of the day convenient for observation - from evening twilight to dawn - you can see bright satellites cutting through the starry sky.

For centuries, man has sought to unravel the mystery of the great world "order" of the Universe, which the ancient Greek philosophers called the Cosmos (translated from Greek - "order", "beauty"), in contrast to the Chaos that preceded, as they believed, the appearance of the Cosmos.

The first natural-scientific ideas about the universe around us that have come down to us were formulated by ancient Greek philosophers in the 7th-5th centuries. BC e. Their natural-philosophical teachings were based on the previously accumulated astronomical knowledge of the Egyptians, Sumerians, Babylonians, Aryans, but differed in the significant role of explanatory hypotheses, the desire to penetrate the hidden mechanism of phenomena.

Observation of the round disks of the Sun, the Moon, the rounded horizon line, as well as the boundaries of the Earth's shadow creeping onto the moon during its eclipses, the correct repetition of day and night, seasons, sunrises and sunsets of the luminaries - all this suggested that the basis of the structure of the universe lies the principle of circular forms and movements, "cyclicality" and uniformity of changes. But up to the 2nd c. BC e. there was no separate doctrine of the sky, which would unite all knowledge in this area into a single system. Ideas about celestial phenomena, as well as phenomena "in the upper air" - literally about "meteor phenomena", for a long time were part of the general speculative teachings about nature as a whole. These teachings were later called physics (from the Greek word "fusis" - nature - in the sense of periods, the essence of things and phenomena). The main content of this ancient semi-philosophical "physics", or in our understanding - rather natural philosophy, which included cosmology and cosmogony as almost the main elements, was the search for that unchanging principle, which, as they thought, underlies the world of changeable phenomena.

All the knowledge about nature accumulated over the centuries, up to technical and everyday experience, was combined, systematized, logically developed to the utmost in the first universal picture of the world, which he created in the 4th century BC. e. the greatest ancient Greek philosopher (and, in fact, the first physicist) Aristotle (384 - 322 BC), who spent most of his life in Athens, where he founded his famous scientific school. It was the doctrine of the structure, properties and movement of everything that is included in the concept of nature. At the same time, Aristotle for the first time separated the world of earthly (or rather, “sublunar”) phenomena from the heavenly world, from the Cosmos itself with its supposedly special laws and the nature of objects. In a special treatise "on the sky" Aristotle drew his natural-philosophical picture of the world.

By the Universe, Aristotle meant all existing matter (consisting, according to his theory, of four ordinary elements - earth, water, air, fire and the fifth - heavenly - the ever-moving ether, which differed from ordinary matter also in that it did not have lightness, no heaviness). Aristotle criticized Anaxagoras for identifying the ether with the usual material element - fire. Thus, the Universe, according to Aristotle, existed in the singular.

In Aristotle's picture of the world, the idea of ​​the interconnectedness of the properties of matter, space and time was first expressed. The universe was presented as finite and limited to a sphere beyond which nothing material could be conceived, and therefore there could be no space itself, since it was defined as something that was (or could be filled with matter). Outside the material universe, there was no time, which Aristotle, with brilliant simplicity and clarity, defined as a measure of movement and associated with matter, explaining that "there is no movement without a physical body." Beyond the material universe, Aristotle placed the non-material, spiritual world of the deity, whose existence was postulated.

The great ancient Greek astronomer Hipparchus (c. 190-125 BC) was the first to try to reveal the mechanism of the observed movements of the stars. To this end, he was the first to use in astronomy the geometric method proposed a hundred years before him by the famous mathematician Apollonius of Perga for describing uneven periodic movements as a result of adding simpler - uniform circular ones. Meanwhile, Plato called for the disclosure of the simple essence of the observed complex astronomical phenomena. Non-uniform periodic motion can be described using circular motion in two ways: either by introducing the concept of an eccentric - a circle along which it is displaced relative to the observer, or by expanding the observed motion into two uniform circular motions, with the observer at the center of the circular motion. In this model, it is not the body itself that moves along the circle around the observer, but the center of the secondary circle (epicycle), along which the body moves. The first circle is called the deferent (carrier). Both models were later used in ancient Greek astronomy. Hipparchus used the first to describe the movement of the Sun and Moon. For the Sun and the Moon, he determined the position of the centers of their eccentrics, and for the first time in the history of astronomy, he developed a method and compiled tables for predicting the moments of eclipses (with an accuracy of 1-2 hours).

Appeared in 134 BC. e. a new star in the constellation of Scorpio led Hipparchus to the idea that changes were taking place in the world of stars. In order to make it easier to notice such changes in the future, Hipparchus compiled a catalog of the positions on the celestial sphere of 850 stars, dividing all the stars into six classes and naming the brightest stars of the first magnitude.

The begun mathematical description of astronomical phenomena almost three centuries later reached its peak in the system of the world of the famous Alexandrian astronomer, geographer and optician Claudius Ptolemy (? - 168). Ptolemy supplemented Hipparchus' catalog with his own observations up to 1022 stars. He invented a new astronomical instrument - the wall circle, which later played a significant role in the medieval astronomy of the East and in the European astronomy of the 16th century, especially in the observations of Tycho Brahe.

His fundamental work - "The Great Mathematical Construction of Astronomy in the XVI Books", in Greek "Meg Ale Syntax", in ancient times was widely known under the name "Mgiste" ("The Greatest"). Europeans learned about it from Arab astronomers - under the distorted name "Al Majisti", or in a Latinized treatment, "Almagest". It presented the entire body of astronomical knowledge ancient world. In this work, Ptolemy uses the mathematical apparatus of spherical astronomy - trigonometry. For centuries, tables of sines he calculated were used.

Based on the achievements of Hipparchus, Ptolemy went further in the study of the then main moving bodies for astronomers. He significantly supplemented and refined the theory of the Moon, rediscovering evection. Calculated by Ptolemy on this basis, more accurate tables of the position of the moon allowed him to improve the theory of eclipses. For determining geographical longitude places of observation accurate prediction of the moment of eclipses was of great importance. But the real scientific feat of the scientist was the creation of the first mathematical theory of the complex visible motion of the planets, to which five of the thirteen books of the Almagest are devoted.

Galaxies have been the subject of cosmogonic research since the 20s of our century, when their real nature was reliably established and it turned out that these are not nebulae, i.e. not clouds of gas and dust that are not far from us, but huge star worlds lying at very large distances from us. The basis of all modern cosmology is one fundamental idea - the idea of ​​gravitational instability dating back to Newton. Matter cannot remain uniformly dispersed in space, because the mutual attraction of all particles of matter tends to create in it concentrations of various scales and masses. In the early Universe, gravitational instability strengthened initially very weak irregularities in the distribution and motion of matter and, at a certain epoch, led to the appearance of strong inhomogeneities: "pancakes" - protoclusters. The boundaries of these compaction layers were shock waves, on the fronts of which the initially non-rotational, irrotational motion of matter acquired vorticity. The breakup of layers into separate clusters also occurred, apparently due to gravitational instability, and this gave rise to protogalaxies. Many of them turned out to be rapidly rotating due to the swirling state of the substance from which they were formed. The fragmentation of protogalactic clouds as a result of their gravitational instability led to the emergence of the first stars, and the clouds turned into star systems - galaxies. Those that had a fast rotation acquired a two-component structure because of this - they formed a halo of a more or less spherical shape and a disk in which spiral arms appeared, where the birth of Protogalaxy stars still continues, for which the rotation was slower or not at all, turned into elliptical or irregular galaxies. In parallel with this process, the formation of a large-scale structure of the Universe took place - superclusters of galaxies arose, which, connecting with their edges, formed a kind of cells or honeycombs; they have been recognized in recent years.

In the 20-30s. XX century Hubble developed the basics of the structural classification of galaxies - giant star systems, according to which there are three classes of galaxies:

I. Spiral galaxies - are characterized by two relatively bright branches arranged in a spiral. The branches come out either from the bright core (such galaxies are denoted by S) or from the ends of the bright bridge crossing the core (designated by SB).

II. Elliptical galaxies (denoted by E) - having the shape of ellipsoids.

Representative - the ring nebula in the constellation Lyra is located at a distance of 2100 light years from us and consists of luminous gas surrounding the central star. This shell was formed when an aging star shed its gaseous covers and they rushed into space. The star shrank and turned into a white dwarf, comparable in mass to our sun, and in size to the Earth.

III. Irregular (irregular) galaxies (denoted by I) - having irregular shapes.

According to the degree of ragged branches, spiral galaxies are divided into subtypes a, b, c. In the first of them, the branches are amorphous, in the second, they are somewhat ragged, in the third, they are very ragged, and the core is always dim and small.

The density of distribution of stars in space increases with approaching the equatorial plane of spiral galaxies. This plane is the plane of symmetry of the system, and most of the stars in their rotation around the center of the galaxy remain close to it; circulation periods are 107 - 109 years. In this case, the internal parts rotate as solid, while at the periphery the angular and linear velocities of circulation decrease with distance from the center. However, in some cases, an even smaller nucleolus ("core") located inside the nucleus rotates the fastest. Irregular galaxies, which are also flat star systems, rotate similarly.

Elliptical galaxies are made up of population type II stars. Rotation was found only in the most compressed of them. As a rule, they do not contain cosmic dust, which is how they differ from irregular and especially spiral galaxies, in which there is a large amount of light-absorbing dust matter.

In spiral galaxies, light-absorbing dust matter is present in greater quantities. It ranges from several thousandths to a hundredth of their total mass. Due to the concentration of dusty matter towards the equatorial plane, it forms a dark band in galaxies that are turned to us with an edge and have the form of a spindle.

Subsequent observations showed that the described classification is not sufficient to systematize the entire variety of shapes and properties of galaxies. Thus, galaxies were discovered that occupy, in a sense, an intermediate position between spiral and elliptical galaxies (denoted by So). These galaxies have a huge central cluster and a flat disk surrounding it, but no spiral arms. In the 60s of the twentieth century, numerous finger-shaped and disk-shaped galaxies were discovered with all gradations of abundance of hot stars and dust. Back in the 1930s, elliptical dwarf galaxies were discovered in the constellations Furnace and Sculptor with extremely low surface brightness, so low that these, one of the closest galaxies to us, are hardly visible against the sky even in their central part. On the other hand, in the early 1960s, many distant compact galaxies were discovered, of which the most distant ones are indistinguishable from stars even through the strongest telescopes. They differ from stars in their spectrum, in which bright emission lines are visible with huge redshifts corresponding to such large distances at which even the brightest single stars cannot be seen. Unlike ordinary distant galaxies, which appear reddish due to a combination of their true energy distribution and redshift, the most compact galaxies (also called quasi-stellar galaxies) are bluish in color. As a rule, these objects are hundreds of times brighter than ordinary supergiant galaxies, but there are also weaker ones. Many galaxies have detected radio emission of a nonthermal nature, which, according to the theory of the Russian astronomer I.S. Shklovsky, occurs when electrons and heavier electrons decelerate in a magnetic field charged particles moving at speeds close to the speed of light (the so-called synchotron radiation), such speeds particles get as a result of grandiose explosions inside galaxies.

Compact distant galaxies with powerful nonthermal radio emission are called N-galaxies.

Star-shaped sources with such radio emission are called quasars (quastellar radio sources), and galaxies with powerful radio emission and significant angular dimensions are called radio galaxies. All these objects are extremely far from us, which makes it difficult to study them. Radio galaxies, which have a particularly powerful non-thermal radio emission, are predominantly elliptical in shape, and spiral ones are also found.

Radio galaxies are galaxies whose nuclei are in the process of decay. The ejected dense parts continue to break up, possibly forming new galaxies - sisters, or satellites of galaxies of smaller mass. In this case, the fragmentation velocities can reach enormous values. Studies have shown that many groups and even clusters of galaxies break up: their members move away from each other indefinitely, as if they were all generated by an explosion.

Supergiant galaxies have luminosities 10 times higher than the luminosity of the Sun, quasars are on average 100 times brighter; the weakest of known galaxies- dwarfs are comparable to ordinary globular star clusters in our galaxy. Their luminosity is about 10 times the luminosity of the sun.

The sizes of galaxies are very diverse and range from tens of parsecs to tens of thousands of parsecs.

The space between galaxies, especially within clusters of galaxies, seems to sometimes contain cosmic dust. Radio telescopes do not detect a tangible amount of neutral hydrogen in them, but cosmic rays penetrate it through and through in the same way as in electromagnetic radiation.

The galaxy consists of many stars of various types, as well as star clusters and associations, gas and dust nebulae, and individual atoms and particles scattered in interstellar space. Most of them occupy a lenticular volume with a diameter of about 30 and a thickness of about 4 kiloparsecs (about 100 thousand and 12 thousand light years, respectively). A smaller part fills an almost spherical volume with a radius of about 15 kiloparsecs (about 50 thousand light years).

All components of the galaxy are linked into a single dynamic system, rotating around a minor axis of symmetry. To an earthly observer inside the galaxy, it appears as the Milky Way (hence its name - "Galaxy") and the whole multitude of individual stars visible in the sky.

Stars and interstellar gas-dust matter fill the volume of the galaxy unevenly: they are most concentrated near the plane perpendicular to the axis of rotation of the galaxy and constituting its plane of symmetry (the so-called galactic plane). Near the line of intersection of this plane with the celestial sphere (the galactic equator) and is visible Milky Way, the middle line of which is almost a great circle, since the solar system is not far from this plane. The Milky Way is a cluster of a huge number of stars merging into a wide whitish band; however, the stars projecting nearby in the sky are vast distances from each other in space, excluding their collisions, despite the fact that they move at high speeds (tens and hundreds of km / s) in the direction of the poles of the galaxy (its north pole is located in constellation Coma Berenices). The total number of stars in the galaxy is estimated at 100 billion.

Interstellar matter is also scattered in space unevenly, concentrating mainly near the galactic plane in the form of globules, individual clouds and nebulae (from 5 to 20 - 30 parsecs in diameter), their complexes or amorphous diffuse formations. Particularly powerful, relatively close to us, dark nebulae appear to the naked eye in the form of dark patches of irregular shapes against the background of the Milky Way band; the scarcity of stars in them is the result of the absorption of light by these non-luminous dust clouds. Many interstellar clouds are illuminated by high-luminosity stars close to them and appear as bright nebulae, as they glow either by reflected light (if they consist of cosmic dust particles) or as a result of the excitation of atoms and their subsequent emission of energy (if the nebulae are gaseous).

Our days with with good reason called the golden age of astrophysics - remarkable and most often unexpected discoveries in the world of stars are now following one after another. The solar system has recently become the subject of direct experimental, and not just observational, research. Flights of interplanetary space stations, orbital laboratories, expeditions to the Moon brought a lot of new specific knowledge about the Earth, near-Earth space, planets, and the Sun. We live in an age of amazing scientific discoveries and great accomplishments. The most incredible fantasies unexpectedly quickly come true. Since ancient times, people have dreamed of unraveling the mysteries of the Galaxies scattered in the boundless expanses of the Universe. One has only to be amazed at how quickly science puts forward various hypotheses and immediately refutes them. However, astronomy does not stand still: new methods of observation appear, old ones are modernized. With the invention of radio telescopes, for example, astronomers can "see" distances that are still in the 40s. years of the twentieth century seemed inaccessible. However, one must clearly imagine the enormous magnitude of this path and the colossal difficulties that are yet to be encountered on the path to the stars.

Milky Way (Greek galaxias) - crossing starry sky silver misty stripe. The Milky Way includes a huge number of visually indistinguishable stars, concentrating towards the main plane of the Galaxy. The Sun is located near this plane, so that most of the stars in the Galaxy are projected onto celestial sphere within a narrow band - the Milky Way. The idea that the Milky Way consists of countless stars was apparently first expressed by Democritus. He believed that the Milky Way is the scattered light of many stars, which, of course, would be visible throughout the sky, but turned out to be hardly noticeable in the sun's rays. Aristotle refuted the latter statement and formulated the correct concept, taking into account the movement of the Earth and the shape of the earth's shadow, but then abandoned it and suggested that the Milky Way is a cluster of vapors of hot celestial bodies.

The width of the Milky Way is different: in the widest places - more than 15 °, in the narrowest - only a few degrees.

The Milky Way passes through the following constellations: Unicorn, Canis Minor, Orion, Gemini, Taurus, Charioteer, Perseus, Giraffe, Cassiopeia, Andromeda, Cepheus, Lizard, Cygnus, Chanterelle, Lyra, Arrow, Eagle, Shield, Sagittarius, Ophiuchus, Southern Crown , Scorpio, Square, Wolf, Southern Triangle, Centaurus, Compass, Southern Cross, Fly, Keel, Sails, Stern.

The heterogeneity of the structure of the Milky Way is caused mainly by two reasons: 1) the actual uneven distribution of stars in the Galaxy, where stellar clouds can be considered as peculiar structural details; 2) the presence of an absorbing medium, which, in the form of dark nebulae, different forms and size gives bizarre outlines. Raggedness is clearly visible in the constellation Cygnus. But especially remarkable is the very bright and dense star cloud in the constellation Scutum. There are several star clouds in the constellation Sagittarius.

Starting from Deneb, the Milky Way descends towards the horizon northern hemisphere the sky with two shining streams. The dark gap between them ("Great Gap"), apparently, is caused by numerous and relatively close to us dark nebulae, which obscure regions of the Milky Way. AT southern hemisphere sky, near the Southern Cross, is the Coal Sack - a black hole in the Milky Way, which XVII observers considered a real hole in the sky.

The middle line inside the Milky Way. is the galactic equator.

The Chinese identified the Milky Way as early as the 6th century BC. BC. as a phenomenon of unknown nature. It was called "Milk Way", Silver River, Sky River, etc.

In an astronomical sense: celestial bodies, which are the source of radiant energy that is created in their depths and radiated into outer space. Most of the visible matter of galaxies is concentrated in stars. Stars are powerful sources of energy. In particular, life on Earth owes its existence to the radiation energy of the Sun. Stars in outer space are not evenly distributed, they form star systems. These include multiple stars, star clusters, and galaxies.

Most of the stars are in a stationary state, i.e. changes in their physical features are not observed. This corresponds to a state of equilibrium. But there are also such stars, the properties of which change in a visible way. They are called variable stars and non-stationary stars. It should be noted the stars in which flares occur continuously or from time to time, in particular, new stars. With outbreaks of the so-called. supernovae, the matter of a star can in some cases be completely dispersed in space.

The characteristics of stars are divided into visible ones (the most important is the brightness, which is usually expressed in the logarithmic scale of the visible magnitudes) and true (luminosity, color of stars, radius, mass). The most important information about the properties of a star is provided by their spectra. Further, there is a classification of stars according to luminosity. The simplest form of this classification is to divide stars into giants and dwarfs. With a more detailed classification, supergiants, subgiants, subdwarfs, etc. are distinguished.

As possible sources of huge energy of stars, modern physics indicates gravitational contraction, leading to the release of gravitational energy, and thermonuclear reactions, as a result of which the nuclei of heavier elements are synthesized from the nuclei of light elements and a large amount of energy is released. The energy of gravitational contraction, as calculations show, would be sufficient to maintain the luminosity of the Sun for only 30 million years, while from geological and other data it follows that the luminosity of the Sun remained approximately constant for billions of years. Gravitational contraction can serve as a source of energy only for very young stars. On the other hand, thermonuclear reactions proceed at a sufficient rate only at temperatures thousands of times higher than the surface temperature of a star. In the interiors of stars at temperatures >10E7 K and enormous densities, the gas has a pressure of billions of atmospheres. Under these conditions, a star can be in a stationary state only due to the fact that in each of its layers the internal gas pressure is balanced by the action of gravitational forces. This state is called hydrostatic equilibrium. Consequently, a stationary star is a gaseous (more precisely, plasma) ball in a state of hydrostatic equilibrium. If the temperature inside the star rises for any reason, the star must swell, because the pressure in its bowels will increase. Gravitational forces will not be able to prevent the expansion of the star, because. near the surface of an expanding star, they will decrease. This implies that in order to maintain hydrostatic equilibrium, stars with a high temperature, other things being equal, must have smaller sizes. All of the above applies to chemically homogeneous (homogeneous) stellar models, which are quite suitable for the vast majority of stars. (Such stars are called main sequence stars, and our Sun also belongs to them). But there are stars whose processes are described by other models (for example, red giants). The stationary state of a star is characterized not only by mechanical, but also by thermal equilibrium: the processes of energy release in the interiors of stars, the processes of heat removal of energy from the interiors to the surface, and the processes of energy radiation from the surface must be balanced. Therefore, stars are stable self-regulating systems.

The luminosity of a star (with the exception of the most massive ones) is proportional to the mass to a power greater than unity. Stock same nuclear energy in stars is simply proportional to the mass. Therefore, the greater the mass of a star, the faster it must use up its internal sources of energy. The periods of evolution are the shorter, the greater the mass of the stars. For the most massive stars, the luminosity is proportional to the mass. The lifetime of such stars ceases to decrease as their mass increases and tends to a certain value of the order of 3.5 million years, which is very small on a cosmic scale. Thus, stars with high luminosities are either young stars (class O blue giants) or stars that have recently entered one or another stage of evolution (red supergiants).

The relative abundance of stars of different types in the Galaxy can be characterized as follows: for every 10 million red dwarfs there are about 1 million white dwarfs, about 1000 giants, and only one supergiant star.

ASTRONOMY (from astro ... and Greek nomos - law), the science of the structure and development of cosmic bodies, the systems they form and the Universe as a whole. Astronomy includes spherical astronomy, practical astronomy, astrophysics, celestial mechanics, stellar astronomy, extragalactic astronomy, cosmogony, cosmology and a number of other sections. Astronomy is the oldest science that arose from the practical needs of mankind (prediction of seasonal phenomena, timekeeping, positioning on the surface of the Earth, etc.). The birth of modern astronomy was associated with the rejection of the geocentric system of the world (Ptolemy, 2nd century) and its replacement by the heliocentric system (N. Copernicus, mid-16th century), with the beginning of telescopic studies of celestial bodies (G. Galileo, early 17th century .) and the discovery of the law of universal gravitation (I. Newton, late 17th century). 18th-19th centuries were for astronomy a period of accumulation of data on the solar system, the galaxy and the physical nature of stars, the sun, planets and other cosmic bodies. In the 20th century In connection with the discovery of the world of galaxies, extragalactic astronomy began to develop. The study of the spectra of galaxies allowed E. Hubble (1929) to detect the general expansion of the Universe, predicted by A. A. Friedman (1922) on the basis of the theory of gravity created by A. Einstein in 1915-16. Scientific and technological revolution of the 20th century. had a revolutionary impact on the development of astronomy in general and astrophysics in particular. The creation of optical and radio telescopes with high resolution, the use of rockets and artificial Earth satellites for extra-atmospheric astronomical observations led to the discovery of a number of new types of cosmic bodies: radio galaxies, quasars, pulsars, X-ray sources, etc. The foundations of the theory of stellar evolution and the cosmogony of the solar system were developed. . The greatest achievement of astrophysics of the 20th century. became relativistic cosmology - the theory of the evolution of the universe as a whole.

Comets (from the Greek kometes - "hairy [star]") - small bodies of the solar system (along with asteroids and meteoroids), moving along highly elongated orbits and dramatically changing their appearance as they approach the Sun. Comets are bodies formed in the outer part of the solar system (including the region of higher planets).

Comets, being far from the Sun, look like foggy, faintly luminous objects (blurred disks with a thickening in the center). As comets approach the Sun, they form a "tail", usually directed in the opposite direction from the Sun. Inside the hazy spot, called the "head" of the comet or coma, a relatively bright nucleus, similar to a star, is sometimes seen, and around the head there are concentric rings-halos. The nucleus of a comet is a large block of frozen gases, inside of which there are also solid particles - from the smallest dust to large stony masses. This ice is not quite ordinary; in addition to water, it contains ammonia and methane. Chemical composition Comet ice resembles the composition of Jupiter. The diameters of the comet nuclei are presumably 0.5–20 km and have a mass on the order of 1014–1019 g. However, comets with much larger nuclei occasionally appear. Numerous nuclei smaller than 0.5 km give rise to faint comets that are practically inaccessible to observations. The apparent diameters of the heads of stars usually range from 10,000 to 1 million km, varying with distance from the sun. In some comets, the maximum size of the head exceeded the size of the Sun. Yet big sizes(over 10 million km) have shells of atomic hydrogen around their heads. As a rule, the tails are less bright than the head, and therefore they can not be observed in all comets. The length of their visible part is 106 -107 km, i.e. usually they are immersed in a hydrogen shell. For some comets, the tail could be traced to a distance of over 100 million km. In the heads and tails of K., the substance is extremely rarefied; despite the gigantic volume of these formations, almost the entire mass of the comet is concentrated in its solid core. The density of the tail is so negligible that faint stars shine through it.

The name "comet" is explained by the fact that bright comets look like a head with loose hair. Every year, 5-10 comets are discovered. Each of them is assigned a preliminary designation, including the name of the discoverer of the comet, the year of discovery and the letter of the Latin alphabet in the order of discovery. It is then replaced by the final designation, including the year of passage through the perihelion and a Roman numeral in order of the dates of passage through the perihelion.

Comets are observed when the nucleus of a comet approaches the Sun closer than 4-6 AU, is heated by its rays and begins to release gas and dust particles.

Most of the observed comets belong to the Solar System and revolve around the Sun in elongated elliptical orbits of various sizes, arbitrarily oriented in space. The dimensions of the orbits of most planets are thousands of times greater than the diameter of the planetary system. Comets are located near the aphelions of their orbits most of the time, so that on the far outskirts of the solar system there is a cloud of comets - the so-called. the Oort cloud (named after the Danish astronomer who proposed this theory). The origin of this cloud is apparently associated with the gravitational ejection of icy bodies from the zone of giant planets during their formation. The Oort cloud contains about 100 billion comet nuclei. For comets receding to the peripheral parts of the Oort cloud (their distances from the Sun can reach 100 thousand AU, and the periods of revolution around the Sun are 1-10 million years), the orbits change under the influence of the attraction of nearby stars. At the same time, some comets acquire a parabolic velocity with respect to the Sun (for such distant distances - about 0.1 km / s) and forever lose contact with the solar system. Others (very few) acquire velocities of the order of 1 m/s, which leads to their movement in an orbit with a perihelion near the Sun, and then they become available for observation. For all comets, when they move in the area occupied by the planet, the orbits change under the influence of the attraction of the planets. At the same time, among the comets that came from the periphery of the Oort cloud, about half acquire hyperbolic orbits and are lost in interstellar space. For others, on the contrary, the size of the orbits decreases, and they begin to return to the Sun more often.

Comets belonging to the solar system, from time to time (with periods from 3.3 years, like Encke's comet, to several tens of thousands of years) pass near the Sun and are called periodic. Away from the Sun, the comet is dimly illuminated by its rays, has no tail, and is not accessible for observation. As it approaches the Sun, its illumination intensifies, the frozen gases of the core, heated by the sun's rays, evaporate and envelop the core with a gas and dust shell that forms the comet's head. Under the influence of light pressure from the sun's rays and elementary particles ejected by the Sun, gas and dust escape from the head of the comet, forming a tail, which in most cases is directed away from the Sun and, depending on the nature of the particles included in it, can have a different shape, from almost perfectly straight (the tail consists of ionized gas molecules) to sharply curved (a tail of heavy dust particles). Some comets have small anomalous tails directed towards the Sun. Some comets have two tails: one is curved, consisting of dust particles; the other is straight, gaseous, elongated in a direction exactly opposite to that of the Sun. Several comets have several dust tails. Comets were observed, the tails of which stretched almost half the sky.

The shape of the tail is described by the following scale: 0 - straight tail; 1 - slightly deviated; 2 - noticeably curved; 3 - sharply curved; 4 - directed towards the Sun.

The apparent length of a comet's tail is estimated in degrees of arc. If the nucleus of a comet is visible, then its brightness is estimated similarly to the brightness of variable stars.

The more often a comet approaches the Sun, the faster it loses its substance. Therefore, periodic orbits that travel relatively close to the Sun (for example, to the orbit of Jupiter or Saturn) and often return to it (short-period ones; about 100 of them are known) cannot be bright. They are not visible naked eye. On the other hand, long-period cosmic rays with long periods of revolution around the Sun are usually very bright near the Sun and visible to the naked eye.

Solar radiation falling on the Earth is, in general, very stable, otherwise life on Earth would be subjected to too large temperature changes. At present, satellites have very carefully measured the energy radiated by the Sun, and have shown that the solar constant is not constant, but subject to variations within tenths of a percent, and long-term variations are associated with the solar cycle (Solar constant - the amount of solar energy coming to a surface of 1 sq.m, deployed perpendicular to the sun's rays in space) From maximum to minimum, the solar constant decreases by about 0.1%, i.e. during the maximum activity (many spots on the Sun) it radiates as if more. These changes may also have an impact on earth climate. The Maunder Low (1645-1715) had very few sunspots. This period is known on Earth as the Little Ice Age: at that time it was much colder than now. In principle, this may be a mere coincidence, but most likely, these events have a causal relationship.

The depth of penetration of solar radiation into the Earth's atmosphere depends on the wavelength of its radiation. Fortunately for life, nitric oxide in the thin layer of the atmosphere above 50 km above the Earth's surface blocks the Sun's highly variable short-wavelength ultraviolet radiation. At lower altitudes, ozone and molecular oxygen absorb the long-wavelength portion of ultraviolet radiation, which is also harmful to life. Changes in solar ultraviolet radiation affect the structure of the ozone layer.

The Earth is also affected by the so-called solar wind due to the quiet emission of coronal plasma. The solar wind has a very strong effect on comet tails and even has measurable effects on the trajectory of satellites. Charged particles from the solar wind are responsible for the northern and southern auroras as they pierce the Earth's atmosphere at high speed and cause it to glow.

The emission of charged particles by the Sun, which depends mainly on conditions in the layers located above the photosphere, also changes in the solar cycle. Highest value among these particles, in terms of their influence on terrestrial processes, are high-energy protons, which are ejected during explosions in the solar corona (high-energy electrons are also ejected at the same time).

High-energy solar protons coming to the Earth have energies from 10 million to 10 billion eV (for comparison, the energy of a photon visible light is about 2 eV). The most energetic protons travel at close to the speed of light and reach the Earth approximately 8 minutes after the most powerful solar flares. Such flares are associated with colossal eruptions in the active regions of the Sun, which sharply increase their brightness in the X-ray and extreme ultraviolet ranges. It is believed that the source of flare energy is the rapid mutual annihilation (annihilation) of strong magnetic fields, during which the plasma is heated and powerful electric fields accelerating charged particles. These particles are able to have a variety of effects on people who at this moment are not under the protection of the earthly magnetic field.

Powerful proton flares are an important factor for planning flights on civil airlines, especially those passing in polar latitudes, where lines of force Earth's magnetic field is directed perpendicular to the Earth's surface and therefore allow charged particles to reach the lower atmosphere. Passengers in this case are exposed to increased radiation exposure. Such phenomena can have an even stronger impact on crews. spacecraft, especially those flying in polar orbits. The influence of proton flashes on the functioning of computing systems was also observed. Thus, in August 1989, one such event paralyzed the work of the Toronto stock exchange computer center. During the solar cycle, only a few dozen such powerful flares occur, and their frequency is much higher at its maximum than at its minimum.

Changes in the plasma flow of the solar wind flowing around the Earth lead to an impact of a completely different type. This relatively low-energy plasma, as it were, escapes from the solar corona, overcoming due to high temperature gravitational attraction Sun. The Earth's magnetic field affects the charged particles of the solar wind and does not allow them to approach the surface of the planet. The space around the Earth, which mostly cannot penetrate the particles of the solar wind, is called the Earth's magnetosphere. Flares and other abrupt changes in the magnetic fields on the Sun lead to disturbances in the solar wind and change the plasma pressure on the Earth's magnetosphere. The changes in the geomagnetic field associated with the impact of the solar wind are only about 0.1% of its strength, which is approximately 1 G. However, induced by even such small changes in the geomagnetic field electric currents in long conductors on the Earth's surface (such as high-voltage lines or oil pipelines) can lead to dramatic consequences. For a long time, numerous attempts were made to find a connection between solar activity and weather. The outstanding English astronomer William Herschel suggested that the Sun shines most brightly at the maximum of sunspots, and an increase in temperature during this period should lead to an increase in the harvest of wheat and, accordingly, a fall in prices for it. . In 1801 he stated that the price of wheat did indeed correlate with the sunspot cycle. The correlation, however, turned out to be unreliable, and Herschel turned to other problems. Many of these seeming connections proved short-lived, and all of them had the disadvantage of being statistical rather than causal. No one has yet proposed a reasonable mechanism by which such small changes in the solar constant could tangibly affect terrestrial processes.

The sun is a spherically symmetrical body in equilibrium. Everywhere at equal distances from the center of this ball, the physical conditions are the same, but they change noticeably as one approaches the center. Density and pressure rapidly increase in depth, where the gas is more strongly compressed by the pressure of the overlying layers. Therefore, the temperature also rises as it approaches the center. Depending on the change in physical conditions, the Sun can be divided into several concentric layers, gradually turning into each other.

At the center of the Sun, the temperature is 15 million degrees, and the pressure exceeds hundreds of billions of atmospheres. The gas is compressed here to a density of about 1.5 105 kg/m3. Almost all of the Sun's energy is generated in the core - the central region with a radius of about 1/3 of the sun.

Through the layers surrounding the central part, this energy is transferred to the outside. First, energy is transferred by radiation. However, each photon takes millions of years to pass through the radiation zone: light is repeatedly absorbed by matter and re-emitted. It is believed that the radiation zone extends approximately 1/3 of the solar radius.

There is a convection zone along the last third of the radius. The reason for the occurrence of mixing (convection) in the outer layers of the Sun is the same as in a boiling kettle: the amount of energy coming from the heater is much greater than that which is removed by heat conduction. Therefore, the substance is forced to move and begins to transfer heat itself.

All layers of the Sun considered above are actually unobservable. Their existence is known either from theoretical calculations or on the basis of indirect data.

Above the convective zone are directly observable layers of the Sun, called its atmosphere. They are better studied, since their properties can be judged from observations.

The solar atmosphere also consists of several different layers. The deepest and thinnest of them is the photosphere, directly observed in the visible continuous spectrum. The thickness of the photosphere is only about 300 km. The deeper the layers of the photosphere, the hotter they are. In the outer colder layers of the photosphere, Fraunhofer absorption lines form against the background of a continuous spectrum.

During the calmest atmosphere of the earth's atmosphere, the characteristic granular structure of the photosphere can be observed through a telescope. The alternation of small light spots - granules - about 1000 km in size, surrounded by dark gaps, creates the impression of a cellular structure - granulation. The appearance of granulation is associated with convection occurring under the photosphere. Individual granules are several hundred degrees hotter than the gas surrounding them, and their distribution over the solar disk changes within a few minutes. Spectral measurements indicate the movement of gas in granules, similar to convective ones: gas rises in granules, and falls between them.

Propagating into the upper layers of the solar atmosphere, the waves that have arisen in the convective zone and in the photosphere transmit to them part of the mechanical energy convective movements and produce heating gases of the subsequent layers of the atmosphere - the chromosphere and corona. As a result, the upper layers of the photosphere with a temperature of about 4500 K turn out to be the "coldest" on the Sun. Both deep into and up from them, the temperature of the gases increases rapidly.

The layer above the photosphere, called the chromosphere, during complete solar eclipses in those minutes when the Moon completely covers the photosphere, it is visible as a pink ring surrounding the dark disk. At the edge of the chromosphere, protruding, as it were, tongues of flame are observed - chromospheric spicules, which are elongated columns of compacted gas. At the same time, one can also observe the spectrum of the chromosphere, the so-called flare spectrum. It consists of bright emission lines of hydrogen, helium, ionized calcium, and other elements that flash suddenly during the total phase of the eclipse. By separating the radiation of the Sun in these lines, one can obtain its image in them. The chromosphere differs from the photosphere in a much more irregular and heterogeneous structure. Noticeably two types of inhomogeneities - bright and dark. They are larger than photospheric granules. In general, the distribution of inhomogeneities forms the so-called chromospheric network, which is especially well seen in the line of ionized calcium. Like granulation, it is a consequence of the movements of gases in the subphotospheric convective zone, only occurring on a larger scale. The temperature in the chromosphere is growing rapidly, reaching tens of thousands of degrees in its upper layers.

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More than once, raising our eyes to the night sky, we wondered - what is in this endless space?

The universe is fraught with many secrets and mysteries, but there is a science called astronomy, which has been studying the cosmos for many years and trying to explain its origin. What is this science? What do astronomers do and what exactly do they study?

What does the word "astronomy" mean?

The term "astronomy" appeared in Ancient Greece in the III-II centuries BC, when scientists such as Pythagoras and Hipparchus shone in the scientific community. The concept is a combination of two ancient Greek words - ἀστήρ (star) and νόμος (law), that is, astronomy is the law of the stars.

This term should not be confused with another concept - astrology, which studies the impact of celestial bodies on the Earth and man.

What is astronomy?

Astronomy is the science of the universe, which determines the location, structure and formation of celestial bodies. In modern times, it includes several sections:

- astrometry, which studies the location and movement of space objects;

- celestial mechanics - determining the mass and shape of stars, studying the laws of their movement under the influence of gravitational forces;



— theoretical astronomy, within which scientists develop analytical and computer models of celestial bodies and phenomena;

– astrophysics – the study of chemical and physical properties space objects.

Separate branches of science are aimed at studying the patterns of the spatial arrangement of stars and planets and considering the evolution of celestial bodies.

In the 20th century, a new section appeared in astronomy called archaeoastronomy, aimed at studying astronomical history and elucidation of knowledge in the field of stars in ancient times.

What does astronomy study?

The objects of astronomy are the Universe as a whole and all objects in it - stars, planets, asteroids, comets, galaxies, constellations. Astronomers study interplanetary and interstellar matter, time, black holes, nebulae, and celestial coordinate systems.



In a word, under their close attention is everything related to space and its development, including astronomical instruments, symbols and.

When did astronomy appear?

Astronomy is one of the most ancient sciences on Earth. It is impossible to name the exact date of its appearance, but it is well known that people have been studying stars since at least the 6th-4th millennium BC.

Many astronomical tables left by the priests of Babylon, calendars of the Mayan tribes, ancient egypt and Ancient China. Ancient Greek scientists made a great contribution to the development of astronomy and the study of celestial bodies. Pythagoras was the first to suggest that our planet has the shape of a ball, and Aristarchus of Samos was the first to draw conclusions about its rotation around the Sun.

For a long time, astronomy was associated with astrology, but in the Renaissance it became a separate science. Thanks to the advent of telescopes, scientists were able to discover the Milky Way galaxy, and at the beginning of the 20th century they realized that the Universe consists of many galactic spaces.

The greatest achievement of modernity was the emergence of a theory about the evolution of the universe, according to which it expands over time.

What is amateur astronomy?

Amateur astronomy is a hobby in which people who are not related to scientific and research centers observe space objects. It must be said that such entertainment makes a significant contribution to general development astronomy.



Lots of interesting and enough important discoveries. In particular, in 1877, the Russian observer Evgraf Bykhanov was the first to express modern views on the formation of the solar system, and in 2009, the Australian Anthony Wesley discovered traces of the fall of a cosmic body (presumably a comet) on the planet Jupiter.