Astronomical activity in the ancient world. The emergence of astronomy as a science and its development

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Astronomy of Ancient Greece

Astronomy of Ancient Greece- astronomical knowledge and the views of those people who wrote in ancient Greek, regardless of the geographical region: Hellas itself, the Hellenized monarchies of the East, Rome or early Byzantium. Covers the period from the 6th century BC. h. to the 5th century AD e. Ancient Greek astronomy is one of the milestones development not only of astronomy as such, but of science in general. In the works of ancient Greek scientists are the origins of many ideas that underlie the science of modern times. Between modern and ancient Greek astronomy there is a relationship of direct succession, while the science of other ancient civilizations influenced modern only through the mediation of the Greeks.

Introduction

Historiography of ancient Greek astronomy

With a few exceptions, the special works of ancient astronomers have not come down to us, and we can restore their achievements mainly on the basis of the writings of philosophers who did not always have an adequate idea of ​​the intricacies of scientific theories and, moreover, were by no means always contemporaries of the scientific achievements about which they write in their books. Often, when reconstructing the history of ancient astronomy, the works of astronomers of medieval India are used, since, as most modern researchers believe, Indian medieval astronomy is largely based on Greek astronomy of the pre-Ptolemaic (and even pre-Hipparchus) period. However, modern historians do not yet have an unambiguous idea of ​​how the development of ancient Greek astronomy took place.

The traditional version of ancient astronomy focuses on explaining the irregularity of planetary motions within the framework of the geocentric system of the world. It is believed that the pre-Socratics played a big role in the development of astronomy, who formulated the idea of ​​nature as an independent being and thus provided a philosophical justification for the search for the internal laws of nature's life. However, the key figure in this is Plato (5th-4th centuries BC), who set the task for mathematicians to express the apparent complex movements of the planets (including backward movements) as the result of adding several simple movements, which were represented as uniform movements in a circle . The teachings of Aristotle played an important role in substantiating this program. The first attempt to solve "Plato's problem" was the theory of homocentric spheres by Eudoxus, followed by the theory of epicycles by Apollonius of Perga. At the same time, scientists did not so much seek to explain celestial phenomena as they considered them as an occasion for abstract geometric problems and philosophical speculation. Accordingly, astronomers were practically not engaged in the development of observational methods and the creation of theories capable of predicting certain celestial phenomena. In this, it is believed, the Greeks were much inferior to the Babylonians, who have long studied the laws of motion of celestial bodies. According to this point of view, a decisive change in ancient astronomy occurred only after the results of the observations of Babylonian astronomers fell into their hands (which happened due to the conquests of Alexander the Great). It was only then that the Greeks developed a taste for closely observing the starry sky and applying geometry to calculate the positions of the stars. It is believed that Hipparchus (second half of the 2nd century BC) was the first to take this path. To this end, he developed a new mathematical apparatus, trigonometry. The culmination of ancient astronomy was the creation of the Ptolemaic theory of planetary motion (second century AD).

According to an alternative point of view, the problem of constructing a planetary theory was not among the main tasks of ancient Greek astronomers at all. According to the supporters of this approach, for a long time the Greeks either did not know about the backward movements of the planets at all, or did not attach much importance to this. The main task of astronomers was to develop a calendar and methods for determining time from the stars. The fundamental role in this is attributed to Eudoxus, but not so much as the creator of the theory of homocentric spheres, but as the developer of the concept of the celestial sphere. Compared with the supporters of the previous point of view, the role of Hipparchus and especially Ptolemy turns out to be even more fundamental, since the task of constructing a theory of the visible movements of the stars on the basis of observational data is associated precisely with these astronomers.

Finally, there is a third point of view, which is, in a sense, the opposite of the second. Its supporters associate the development of mathematical astronomy with the Pythagoreans, who are credited with the creation of the concept of the celestial sphere, and the formulation of the problem of constructing a theory of backward movements, and even the first theory of epicycles. Supporters of this point of view dispute the thesis about the non-empirical nature of astronomy of the pre-Hipparchus period, pointing to the high accuracy of astronomical observations of astronomers of the 3rd century BC. e. and the use of these data by Hipparchus to build his theories of the motion of the Sun and the Moon, the widespread use in cosmology of speculation about the unobservability of the parallaxes of planets and stars; some results of the observations of Greek astronomers were available to their Babylonian counterparts. The foundations of trigonometry as the mathematical foundation of astronomy were also laid by astronomers of the 3rd century BC. e. A significant stimulus for the development of ancient astronomy was the creation in the III century BC. e. Aristarchus of Samos of the heliocentric system of the world and its subsequent development, including from the point of view of the dynamics of the planets. At the same time, heliocentrism is considered to be well-rooted in ancient science, and its rejection is associated with extra-scientific, in particular religious and political, factors.

Scientific Method of Ancient Greek Astronomy

The main achievement of the astronomy of the ancient Greeks should be considered the geometrization of the universe, which includes not only the systematic use of geometric constructions to represent celestial phenomena, but also a rigorous logical proof of statements along the lines of Euclidean geometry.

The dominant methodology in ancient astronomy was the ideology of “saving phenomena”: it is necessary to find such a combination of uniform circular motions that can be used to simulate any unevenness in the visible movement of the luminaries. The "rescue of phenomena" was conceived by the Greeks as a purely mathematical problem, and it was not assumed that the combination of uniform circular motions found had any relation to physical reality. The task of physics was considered to be the search for an answer to the question "Why?", that is, the establishment of the true nature of celestial objects and the causes of their movements based on the consideration of their substance and the forces acting in the Universe; the use of mathematics in this case was not considered necessary.

periodization

The history of ancient Greek astronomy can be roughly divided into four periods associated with various stages in the development of ancient society:

• Archaic (pre-scientific) period (until the 6th century BC): the formation of the polis structure in Hellas;
• Classical period (VI-IV centuries BC): the heyday of the ancient Greek policy;
• Hellenistic period (III-II centuries BC): the heyday of large monarchical powers that arose on the ruins of the empire of Alexander the Great; from the point of view of science, Ptolemaic Egypt, with its capital in Alexandria, plays a special role;
• The period of decline (I century BC - I century AD), associated with the gradual extinction of the Hellenistic powers and the strengthening of the influence of Rome;
• Imperial period (2nd-5th centuries CE): the unification of the entire Mediterranean, including Greece and Egypt, under the rule of the Roman Empire.

This periodization is rather schematic. In a number of cases it is difficult to establish the affiliation of one or another achievement to one or another period. So, although the general character of astronomy and science in general in the classical and Hellenistic periods looks quite different, on the whole, development in the 6th-2nd centuries BC e. appears to be more or less continuous. On the other hand, a number of scientific achievements of the last, imperial period (especially in the field of astronomical instrumentation and, possibly, theory) are nothing more than a repetition of the successes achieved by astronomers of the Hellenistic era.

Pre-scientific period (until the 6th century BC)

The poems of Homer and Hesiod give an idea of ​​the astronomical knowledge of the Greeks of this period: a number of stars and constellations are mentioned there, practical advice is given on the use of celestial bodies for navigation and for determining the seasons of the year. Cosmological ideas of this period were entirely borrowed from myths: the Earth is considered flat, and the sky is a solid bowl based on the Earth.

At the same time, according to the opinion of some historians of science, the members of one of the Hellenic religious and philosophical unions of that time (the Orphics) also knew some special astronomical concepts (for example, ideas about some celestial circles). However, most researchers do not agree with this opinion.

Classical period (from VI - to IV century BC)

The main actors of this period are philosophers who intuitively grope for what will later be called the scientific method of cognition. At the same time, the first specialized astronomical observations are being made, the theory and practice of the calendar is being developed; for the first time, geometry is taken as the basis of astronomy, a number of abstract concepts of mathematical astronomy are introduced; attempts are being made to find physical patterns in the movement of the luminaries. A number of astronomical phenomena were scientifically explained, the sphericity of the Earth was proved. At the same time, the connection between astronomical observations and theory is still not strong enough; there is too much speculation based on purely aesthetic considerations.

Sources

Only two specialized astronomical works of this period have come down to us, treatises About the rotating sphere and About the rising and setting of the stars Autolycus of Pitana - textbooks on the geometry of the celestial sphere, written at the very end of this period, around 310 BC. e. They are also accompanied by a poem phenomena Arata from Sol (written, however, in the first half of the 3rd century BC), which contains a description of the ancient Greek constellations (a poetic transcription of the works of Eudoxus of Cnidus that have not come down to us, 4th century BC).

Questions of an astronomical nature are often touched upon in the works ancient Greek philosophers: some dialogues of Plato (especially Timaeus, as well as State, Phaedo, Laws, Afterlaw), treatises of Aristotle (especially About Heaven, as well as meteorology, Physics, Metaphysics). The works of philosophers of an earlier time (pre-Socratics) have come down to us only in a very fragmentary form through second, and even third hands.

Presocratics, Plato

During this period, two fundamentally different philosophical approaches were developed in science in general and astronomy in particular. The first of them originated in Ionia and therefore can be called Ionian. It is characterized by attempts to find the material fundamental principle of being, by changing which philosophers hoped to explain all the diversity of nature. In the movement of celestial bodies, these philosophers tried to see manifestations of the same forces that operate on Earth. Initially, the Ionian direction was represented by the philosophers of the city of Miletus Thales, Anaximander and Anaximenes. This approach found its supporters in other parts of Hellas. Among the Ionians is Anaxagoras of Klazomenos, who spent a significant part of his life in Athens, Empedocles of Akragas, to a large extent a native of Sicily. The Ionian approach reached its peak in the writings of the ancient atomists: Leucippus (probably also from Miletus) and Democritus from Abdera, who were the forerunners of mechanistic philosophy.

The desire to give a causal explanation of natural phenomena was the strength of the Ionians. In the present state of the world, they saw the result of the action of physical forces, and not mythical gods and monsters. The Ionians considered the heavenly bodies to be objects, in principle, of the same nature as the earthly stones, the movement of which is controlled by the same forces that act on Earth. They considered the daily rotation of the firmament to be a relic of the original vortex motion, covering all the matter of the Universe. The Ionian philosophers were the first to be called physicists. However, the shortcoming of the teachings of the Ionian natural philosophers was an attempt to create physics without mathematics. The Ionians did not see the geometric basis of the Cosmos.

The second direction of early Greek philosophy can be called Italian, since it received its initial development in Greek colonies the Italian peninsula. Its founder Pythagoras founded the famous religious and philosophical union, whose representatives, unlike the Ionians, saw the basis of the world in mathematical harmony, more precisely, in the harmony of numbers, while striving for the unity of science and religion. They considered the heavenly bodies to be gods. This was justified as follows: the gods are a perfect mind, they are characterized by the most perfect type of movement; this is the circumferential motion, because it is eternal, has no beginning and no end, and always passes into itself. As astronomical observations show, celestial bodies move in circles, therefore, they are gods. The heir of the Pythagoreans was the great Athenian philosopher Plato, who believed that the entire Cosmos was created by an ideal deity in his own image and likeness. Although the Pythagoreans and Plato believed in the divinity of the heavenly bodies, they were not characterized by faith in astrology: an extremely skeptical review of it by Eudoxus, a student of Plato and a follower of the philosophy of the Pythagoreans, is known.

The desire to search for mathematical patterns in nature was the strength of the Italians. The Italian passion for ideal geometric shapes allowed them to be the first to suggest that the Earth and celestial bodies are spherical and open the way to the application of mathematical methods to the knowledge of nature. However, believing the celestial bodies to be deities, they almost completely expelled physical forces from heaven.

Aristotle

The strengths of these two research programs, Ionian and Pythagorean, complemented each other. An attempt to synthesize them can be considered the teaching of Aristotle from Stagira. Aristotle divided the universe into two radically different parts, lower and upper (the sublunar and supralunar regions, respectively). The sublunar (i.e., closer to the center of the Universe) region resembles the constructions of the Ionian philosophers of the pre-atomistic period: it consists of four elements - earth, water, air, fire. This is the area of ​​changeable, impermanent, transient - that which cannot be described in the language of mathematics. On the contrary, the supralunar region is the region of the eternal and unchanging, generally corresponding to the Pythagorean-Platonic ideal of perfect harmony. It is made up of ether - a special kind of matter that is not found on Earth.

Although Aristotle did not call the celestial bodies gods, he considered them to be of a divine nature, since for their constituent element, ether, it is characteristic uniform motion in a circle around the center of the world; this motion is eternal since there are no boundary points on the circle.

Practical astronomy

Only fragmentary information about the methods and results of observations by astronomers of the classical period has come down to us. Based on the available sources, it can be assumed that one of the main objects of their attention was the rising of the stars, since the results of such observations could be used to determine the time at night. A treatise with data from such observations was compiled by Eudoxus of Cnidus (second half of the 4th century BC); the poet Arat from Sol clothed the treatise of Eudoxus in a poetic form.

Almost nothing is known about the astronomical instruments of the Greeks of the classical period. It was reported about Anaximander of Miletus that he used a gnomon, the oldest astronomical instrument, which is a vertically located rod, to recognize the equinoxes and solstices. Eudoxus is also credited with the invention of the "spider" - the main structural element of the astrolabe.

Spherical Sundial

To calculate the time during the day, apparently, a sundial was often used. First, spherical sundials (skafe) were invented as the simplest ones. Improvements in sundial design have also been attributed to Eudoxus. It was probably the invention of one of the varieties of flat sundials.

Ionian philosophers believed that the movement of heavenly bodies was controlled by forces similar to those that operate on an earthly scale. So, Empedocles, Anaxagoras, Democritus believed that celestial bodies do not fall to Earth, since they are held by centrifugal force. The Italians (Pythagoreans and Plato) believed that the luminaries, being gods, move by themselves, like living beings.

There has been considerable disagreement among philosophers about what is outside the Cosmos. Some philosophers believed that there is an infinite empty space; according to Aristotle, there is nothing outside the Cosmos, not even space; atomists Leucippus, Democritus and their supporters believed that behind our world (limited by the sphere of fixed stars) there are other worlds. The closest to modern were the views of Heraclid Pontus, according to which the fixed stars are other worlds located in infinite space.

Explanation of astronomical phenomena and the nature of celestial bodies

The classical period is characterized by widespread speculation about the nature of celestial bodies. Anaxagoras of Klazomen (5th century BC) was the first to suggest that the Moon shines by the reflected light of the Sun, and on this basis, for the first time in history, he gave a correct explanation of the nature of the lunar phases and solar and lunar eclipses. Anaxagoras considered the sun to be a giant stone (the size of the Peloponnese), heated by friction against the air (for which the philosopher almost suffered the death penalty, since this hypothesis was considered contrary to the state religion). Empedocles considered the Sun not an independent object, but a reflection in the firmament of the Earth, illuminated by heavenly fire. The Pythagorean Philolaus believed that the Sun is a transparent spherical body, luminous because it refracts the light of heavenly fire; what we see as daylight is the image produced in the Earth's atmosphere. Some philosophers (Parmenides, Empedocles) believed that the brightness of the daytime sky is due to the fact that the firmament consists of two hemispheres, light and dark, the period of revolution of which around the Earth is a day, like the period of revolution of the Sun. Aristotle believed that the radiation we receive from celestial bodies is not generated by them themselves, but by the air they heat up (part of the sublunar world).

Comets attracted great attention of Greek scientists. The Pythagoreans considered them to be a kind of planets. The same opinion was shared by Hippocrates of Chios, who also believed that the tail does not belong to the comet itself, but is sometimes acquired in its wanderings in space. These opinions were rejected by Aristotle, who considered comets (like meteors) to be the ignition of the air in the upper part of the sublunar world. The reason for these ignitions lies in the heterogeneity of the air surrounding the Earth, the presence of easily flammable inclusions in it, which flare up due to the transfer of heat from the ether rotating over the sublunar world.

According to Aristotle, the Milky Way has the same nature; the only difference is that in the case of comets and meteors, the glow occurs due to the heating of the air by one particular star, while Milky Way arises from the heating of air by the entire supralunar region. Some Pythagoreans, along with Oenopides of Chios, considered the Milky Way to be a scorched trajectory along which the Sun once circulated. Anaxagoras believed the Milky Way to be an apparent cluster of stars, located in the place where the earth's shadow falls on the sky. An absolutely correct point of view was expressed by Democritus, who believed that the Milky Way is a joint glow of many nearby stars.

Mathematical astronomy

The main achievement of mathematical astronomy of the period under review is the concept of the celestial sphere. Probably, initially it was a purely speculative idea based on considerations of aesthetics. However, later it was realized that the phenomena of sunrise and sunset of the luminaries, their climaxes really occur in such a way as if the stars were rigidly fastened to a spherical firmament, rotating around an axis inclined to the earth's surface. Thus, the main features of the movements of stars were naturally explained: each star always rises at the same point on the horizon, different stars pass different arcs across the sky at the same time, and the closer the star to the celestial pole, the smaller the arc it passes in one and the same time. A necessary stage in the work on the creation of this theory should have been the realization that the size of the Earth is immeasurably small compared to the size of the celestial sphere, which made it possible to neglect the daily parallaxes of stars. The names of the people who made this most important intellectual revolution have not come down to us; most likely they belonged to the Pythagorean school. The earliest handbook on spherical astronomy that has come down to us belongs to Autolycus of Pitana (about 310 BC). It was proved there, in particular, that points of a rotating sphere that do not lie on its axis, during uniform rotation, describe parallel circles perpendicular to the axis, and in equal time all points of the surface describe similar arcs.

Another major achievement of mathematical astronomy in classical Greece is the introduction of the concept of the ecliptic - a large circle inclined with respect to the celestial equator, along which the Sun moves among the stars. This idea was probably introduced by the famous geometer Oenopides of Chios, who also made the first attempt to measure the inclination of the ecliptic to the equator (24 °).

A system of four concentric spheres used to model the motion of the planets in the Eudoxian theory. The numbers indicate the spheres responsible for the daily rotation of the sky (1), for the movement along the ecliptic (2), for the backward movements of the planet (3 and 4). T - Earth, the dotted line represents the ecliptic (the equator of the second sphere).

The ancient Greek astronomers put the following principle at the basis of the geometric theories of the motion of celestial bodies: the motion of each planet, the Sun and the Moon is a combination of uniform circular motions. This principle, proposed by Plato or even the Pythagoreans, comes from the idea of ​​​​celestial bodies as deities, which can only have the most perfect type of movement - uniform movement in a circle. It is believed that the first theory of the motion of celestial bodies based on this principle was proposed by Eudoxus of Cnidus. It was the theory of homocentric spheres - a kind of geocentric system of the world, in which celestial bodies are considered rigidly attached to a combination of rigid spheres fastened together with a common center. The improvement of this theory was carried out by Callippus of Cyzicus, and Aristotle put it at the basis of his cosmological system. The theory of homocentric spheres was subsequently abandoned, since it assumes the invariability of the distances from the luminaries to the Earth (each of the luminaries moves along a sphere whose center coincides with the center of the Earth). However, by the end of the classical period, a significant amount of evidence had already been accumulated that the distances of celestial bodies from the Earth actually change: significant changes in the brightness of some planets, the variability of the angular diameter of the Moon, the presence of total and annular solar eclipses.

Hellenistic period (III-II centuries BC)

The most important organizing role in the science of this period is played by the Library of Alexandria and Museion. Although at the beginning of the Hellenistic period two new philosophical schools, the Stoics and the Epicureans, emerged, scientific astronomy had already reached a level that allowed it to develop practically without being influenced by certain philosophical doctrines (it is possible, however, that religious prejudices associated with the philosophy of Stoicism , had a negative impact on the propagation of the heliocentric system: see Cleanf's example below).

Astronomy becomes an exact science. The most important tasks of astronomers are: (1) establishing the scale of the world based on the theorems of geometry and astronomical observations, as well as (2) building predictive geometric theories of the motion of celestial bodies. The technique of astronomical observations reaches a high level. The unification of the ancient world by Alexander the Great makes possible the enrichment of Greek astronomy due to the achievements of the Babylonian astronomers. At the same time, the gap between the goals of astronomy and physics is deepening, which was not so obvious in the previous period.

During most of the Hellenistic period, the Greeks do not trace the influence of astrology on the development of astronomy.

Sources

Six works of astronomers of this period have come down to us:

The achievements of this period formed the basis of two elementary astronomy textbooks, Geminus (1st century BC) and Cleomedes (lifetime unknown, most likely between the 1st century BC and the 2nd century AD), known as Introduction to Phenomena. Claudius Ptolemy tells about the works of Hipparchus in his fundamental work - Almagest (2nd half of the 2nd century AD). In addition, various aspects of astronomy and cosmology of the Hellenistic period are covered in a number of commentary works of later periods.

Philosophical Foundation of Astronomy

The Hellenistic period was marked by the emergence of new philosophical schools, two of which (Epicureans and Stoics) played a prominent role in the development of cosmology.

In order to improve the calendar, scientists of the Hellenistic era made observations of the solstices and equinoxes: the length of the tropical year is equal to the time interval between two solstices or equinoxes, divided by the total number of years. They understood that the accuracy of the calculation is higher, the greater the interval between the events used. Such observations were made, in particular, by Aristarchus of Samos, Archimedes of Syracuse, Hipparchus of Nicaea and a number of other astronomers whose names are unknown.

However, the discovery of precession is usually attributed to Hipparchus, who showed the movement of the equinoxes among the stars as a result of comparing the coordinates of some stars measured by Timocharis and himself. According to Hipparchus, the angular velocity of the equinoxes is 1° per century. The same value follows from the values ​​of the sidereal and tropical year according to Aristarchus, restored from the Vatican manuscripts (in fact, the magnitude of the precession is 1 ° in 72 years).

In the second half of the III century BC. e. Alexandrian astronomers also made observations of the positions of the planets. Among them were Timocharis as well as astronomers whose names we do not know (all we know about them is that they used the zodiac calendar of Dionysius to date their observations). The motives behind the Alexandrian observations are not entirely clear.

In order to determine the geographical latitude in various cities observations were made of the height of the sun during the solstices. In this case, an accuracy of the order of several arc minutes was achieved, the maximum achievable with the naked eye. To determine the longitude, observations of lunar eclipses were used (the difference in longitude between two points is equal to the difference in local time when the eclipse occurred).

equatorial ring.

astronomical instruments. Probably, a diopter was used to observe the position of night luminaries, and a midday circle was used to observe the Sun; the use of the astrolabe (whose invention is sometimes attributed to Hipparchus) and the armillary sphere is also highly likely. According to Ptolemy, Hipparchus used the equatorial ring to determine the moments of the equinoxes.

Cosmology

Having received support from the Stoics, the geocentric system of the world continued to be the main cosmological system in the Hellenistic period. An essay on spherical astronomy written by Euclid at the beginning of the 3rd century BC. e., is also based on a geocentric point of view. However, in the first half of this century, Aristarchus of Samos proposed an alternative, heliocentric system of the world, according to which

• The sun and stars are still
• The sun is at the center of the world
• The Earth revolves around the Sun in a year and around its axis in a day.

Based on the heliocentric system and the unobservability of the annual parallaxes of stars, Aristarchus made the pioneering conclusion that the distance from the Earth to the Sun is negligible compared to the distance from the Sun to the stars. This conclusion with a sufficient degree of sympathy is given by Archimedes in his essay Calculus of grains of sand(one of the main sources of our information about the Aristarchus hypothesis), which can be considered an indirect recognition of heliocentric cosmology by the Syracusan scientist. Perhaps, in his other works, Archimedes developed a different model of the structure of the Universe, in which Mercury and Venus, as well as Mars, revolve around the Sun, which, in turn, moves around the Earth (while the path of Mars around the Sun covers the Earth).

Most historians of science believe that the heliocentric hypothesis did not receive any significant support from Aristarchus' contemporaries and later astronomers. Some researchers, however, provide a number of indirect evidence of the widespread support for heliocentrism by ancient astronomers. However, the name of only one supporter of the heliocentric system is known: the Babylonian Seleucus, 1st half of the 2nd century BC. e.

There is reason to believe that other astronomers also made estimates of the distances to celestial bodies based on the unobservability of their daily parallaxes; one should also recall the conclusion of Aristarchus about the enormous remoteness of the stars, made on the basis of the heliocentric system and the unobservability of the annual parallaxes of stars.

Apollonius of Perga and Archimedes were also involved in determining the distances to heavenly bodies, but nothing is known about the methods they used. One recent attempt at reconstructing Archimedes' work concluded that his distance to the Moon was about 62 Earth radii and fairly accurately measured the relative distances from the Sun to the planets Mercury, Venus, and Mars (based on a model in which these planets revolve around Sun and with it - around the Earth).

To this must be added the determination of the radius of the Earth by Eratosthenes. To this end, he measured the zenithal distance of the Sun at noon on the day of the summer solstice in Alexandria, obtaining a result of 1/50 of a full circle. Further, Eratosthenes knew that in the city of Siena on this day the Sun is exactly at its zenith, that is, Siena is on the tropic. Assuming these cities to lie exactly on the same meridian and taking the distance between them equal to 5000 stadia, and also considering the rays of the Sun to be parallel, Eratosthenes received the circumference of the earth equal to 250,000 stadia. Subsequently, Eratosthenes increased this value to a value of 252,000 stadia, more convenient for practical calculations. The accuracy of Eratosthenes' result is difficult to assess, since the magnitude of the stad he used is unknown. In most modern works, the stages of Eratosthenes are taken to be 157.5 meters or 185 meters. Then his result for the length of the earth's circumference, in terms of modern units of measurement, will be equal to, respectively, 39690 km (only 0.7% less than the true value), or 46620 km (17% more than the true value).

Theories of motion of celestial bodies

During the period under review, new geometric theories of the motion of the Sun, Moon and planets were created, which were based on the principle that the motion of all celestial bodies is a combination of uniform circular motions. However, this principle acted not in the form of the theory of homocentric spheres, as in the science of the previous period, but in the form of the theory of epicycles, according to which the luminary itself makes a uniform movement in a small circle (epicycle), the center of which moves uniformly around the Earth in a large circle (deferent). The foundations of this theory are believed to have been laid by Apollonius of Perga, who lived at the end of the 3rd - beginning of the 2nd century BC. e.

A number of theories of the motion of the Sun and Moon were built by Hipparchus. According to his theory of the Sun, the periods of movement along the epicycle and the deferent are the same and equal to one year, their directions are opposite, as a result of which the Sun uniformly describes a circle (eccenter) in space, the center of which does not coincide with the center of the Earth. This made it possible to explain the non-uniformity of the apparent motion of the Sun along the ecliptic. The parameters of the theory (the ratio of the distances between the centers of the Earth and the eccentric, the direction of the line of apsides) were determined from observations. A similar theory was created for the Moon, however, under the assumption that the velocities of the Moon along the deferent and the epicycle do not match. These theories enabled eclipse predictions to be made with an accuracy not available to earlier astronomers.

Other astronomers were engaged in the creation of theories of the motion of the planets. The difficulty was that there were two types of unevenness in the motion of the planets:

• inequality relative to the Sun: for the outer planets - the presence of backward movements, when the planet is observed near opposition to the Sun; for the inner planets - backward movements and "attachment" of these planets to the Sun;
• zodiacal inequality: the dependence of the size of the arcs of backward movements and the distances between the arcs on the sign of the zodiac.

To explain these inequalities, Hellenistic astronomers used a combination of movements in eccentric circles and epicycles. These attempts were criticized by Hipparchus, who, however, did not offer any alternative, confining himself to systematizing the observational data available at his time.

Right triangle of Aristarchus: relative position of the Sun, Moon and Earth during the quadrature

The main advances in the development of the mathematical apparatus of Hellenistic astronomy were associated with the development of trigonometry. The need to develop trigonometry on a plane was associated with the need to solve two types of astronomical problems:

• Determination of distances to celestial bodies (starting at least with Aristarchus of Samos, who dealt with the problem of determining the distances and sizes of the Sun and Moon),
• Determination of the parameters of the system of epicycles and/or eccentrics representing the motion of the luminary in space (according to widespread opinion, this problem was first formulated and solved by Hipparchus when determining the elements of the orbits of the Sun and the Moon; perhaps astronomers of an earlier time were engaged in similar tasks, but the results of their works have not reached us).

In both cases, astronomers needed to calculate the sides of right-angled triangles given the known values ​​of two of its sides and one of the catches (determined from astronomical observations on the earth's surface). The first work that has come down to us, where this mathematical problem was posed and solved, was a treatise by Aristarchus of Samos On the magnitudes and distances of the sun and moon. In a right-angled triangle formed by the Sun, Moon and Earth during the quadrature, it was required to calculate the value of the hypotenuse (the distance from the Earth to the Sun) through the leg (the distance from the Earth to the Moon) at known value included angle (87°), which is equivalent to calculating sin 3°. According to Aristarchus, this value lies in the range from 1/20 to 1/18. Along the way, he proved, in modern terms, an inequality (contained also in Calculus of grains of sand Archimedes).

Historians have not reached a consensus about the extent to which astronomers of the Hellenistic period developed the geometry of the celestial sphere. Some researchers argue that at least in the time of Hipparchus, the ecliptic or equatorial coordinate system was used to record the results of astronomical observations. Perhaps then some theorems of spherical trigonometry were known, which could be used to compile star catalogs and in geodesy.

Hipparchus' work also contains signs of familiarity with the stereographic projection used in the construction of astrolabes. The discovery of stereographic projection is attributed to Apollonius of Perga; in any case, he proved an important theorem underlying it.

Period of decline (1st century BC - 1st century AD)

During this period, activity in the field of astronomical science is close to zero, but astrology, which came from Babylon, is in full bloom. As evidenced by the numerous papyri of Hellenistic Egypt of that period, horoscopes were drawn up not on the basis of geometric theories developed by the Greek astronomers of the previous period, but on the basis of the much more primitive arithmetic schemes of the Babylonian astronomers. In the II century. BC. a synthetic doctrine arose, which included Babylonian astrology, Aristotle's physics and the Stoic doctrine of the sympathetic connection of all things, developed by Posidonius of Apamea. Part of it was the idea of ​​the conditionality of earthly phenomena by the rotation of the celestial spheres: since the "sublunar" world is constantly in a state of eternal becoming, while the "supralunar" world is in an unchanged state, the second is the source of all changes occurring in the first.

Despite the lack of development of science, there is no significant degradation either, as evidenced by the good quality textbooks that have come down to us. Introduction to Phenomena Gemina (I century BC) and Spherica Theodosius of Bithynia (2nd or 1st century BC). The latter is intermediate in level between similar works of early authors (Autolycus and Euclid) and the later treatise "Sphere" by Menelaus (1st century AD). Also, two more small works of Theodosius have come down to us: About dwellings, which provides a description of the starry sky from the point of view of observers located at different geographical latitudes, and About days and nights where the motion of the Sun along the ecliptic is considered. The technology associated with astronomy was also preserved, on the basis of which the mechanism from Antikythera was created - a calculator of astronomical phenomena, created in the 1st century BC. e.

Imperial period (II-V centuries AD)

Astronomy is gradually reviving, but with a noticeable admixture of astrology. During this period, a number of generalizing astronomical works were created. However, the new heyday is rapidly replaced by stagnation and then a new crisis, this time even deeper, associated with the general decline of culture during the collapse of the Roman Empire, as well as with a radical revision of the values ​​of ancient civilization, produced by early Christianity.

Sources

Astronomy issues are also considered in a number of commentary works written during this period (authors: Theon of Smyrna, II century AD, Simplicius, V century AD, Censorinus, III century AD, Pappus of Alexandria, III or 4th century CE, Theon of Alexandria, 4th century CE, Proclus, 5th century CE, etc.). Some astronomical issues are also considered in the works of the encyclopedist Pliny the Elder, the philosophers Cicero, Seneca, Lucretius, the architect Vitruvius, the geographer Strabo, the astrologers Manilius and Vettius Valens, the mechanic Heron of Alexandria, the theologian Synesius of Cyrene.

Practical astronomy

Triquetrum of Claudius Ptolemy (from a 1544 book)

The task of planetary observations of the period under consideration is to provide numerical material for the theories of the motion of the planets, the Sun and the Moon. For this purpose, Menelaus of Alexandria, Claudius Ptolemy and other astronomers made their observations (there is a tense discussion on the authenticity of Ptolemy's observations). In the case of the Sun, the main efforts of astronomers were still aimed at accurately fixing the moments of the equinoxes and solstices. In the case of the Moon, eclipses were observed (the exact moment of the largest phase and the position of the Moon among the stars were recorded), as well as quadrature moments. For the inner planets (Mercury and Venus), the greatest elongations were of primary interest when these planets are at the greatest angular distance from the Sun. With the outer planets, special emphasis was placed on fixing the moments of opposition with the Sun and their observation at intermediate times, as well as on studying their backward movements. Astronomers also paid much attention to such rare phenomena as the conjunctions of planets with the Moon, stars, and with each other.

Observations of the coordinates of stars were also made. Ptolemy cites a star catalog in the Almagest, where, according to him, he observed each star independently. It is possible, however, that this catalog is almost entirely the catalog of Hipparchus with the coordinates of stars recalculated due to precession.

The last astronomical observations in antiquity were made at the end of the 5th century by Proclus and his students Heliodorus and Ammonius.

Mathematical apparatus of astronomy

The development of trigonometry continued. Menelaus of Alexandria (circa 100 CE) wrote a monograph Spherica in three books. In the first book, he outlined the theory of spherical triangles, similar to Euclid's theory of flat triangles, presented in Book I Began. In addition, Menelaus proved a theorem for which there is no Euclidean analogue: two spherical triangles are congruent (compatible) if the corresponding angles are equal. Another theorem of his states that the sum of the angles of a spherical triangle is always greater than 180°. Second book Spheres expounds on the application of spherical geometry to astronomy. The third book contains "the theorem of Menelaus", also known as the "rule of six magnitudes".

The most significant trigonometric work of antiquity is the Ptolemaic Almagest. The book contains new tables of chords. To calculate them, the chord used (in Chapter X) Ptolemy's theorem (known, however, to Archimedes), which states: the sum of the products of the lengths of opposite sides of a convex inscribed in a circle quadrilateral is equal to the product of the lengths of its diagonals. From this theorem, it is easy to derive two formulas for the sine and cosine of the sum of angles, and two more for the sine and cosine of the difference of angles. Later, Ptolemy gives an analogue of the formula for the sine of a half angle for chords.

The parameters of planetary motion along epicycles and deferents were determined from observations (although it is still unclear whether these observations were falsified). The accuracy of the Ptolemaic model is: for Saturn - about 1/2 °, Jupiter - about 10", Mars - more than 1 °, Venus and especially Mercury - up to several degrees.

Cosmology and physics of the sky

In Ptolemy's theory, the following order of the luminaries was assumed with increasing distance from the Earth: Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn, fixed stars. At the same time, the average distance from the Earth grew with the growth of the period of revolution among the stars; still remained unsolved the problem of Mercury and Venus, which have this period equal to the solar (Ptolemy does not give a sufficiently convincing argument why he places these problems "below" the Sun, simply referring to the opinion of scientists of an earlier period). All stars were considered to be located on the same sphere - the sphere of fixed stars. To explain the precession, he was forced to add another sphere, which is above the sphere of the fixed stars.

Epicycle and deferent according to the theory of nested spheres.

In the theory of epicycles, including that of Ptolemy, the distance from the planets to the Earth varied. The physical picture that may be behind this theory was described by Theon of Smyrna (end of the 1st - beginning of the 2nd century AD) in a work that has come down to us Mathematical concepts useful for reading Plato. This is the theory of nested spheres, the main provisions of which are as follows. Imagine two concentric spheres made of solid material, between which a small sphere is placed. The arithmetic mean of the radii of large spheres is the radius of the deferent, and the radius of the small sphere is the radius of the epicycle. Rotating the two large spheres will cause the small sphere to rotate between them. If a planet is placed on the equator of a small sphere, then its motion will be exactly the same as in the theory of epicycles; thus the epicycle is the equator of a minor sphere.

This theory, with some modifications, was also held by Ptolemy. It is described in his work Planetary hypotheses. It notes, in particular, that the maximum distance to each of the planets is equal to the minimum distance to the planet following it, that is, the maximum distance to the Moon is equal to the minimum distance to Mercury, etc. Ptolemy was able to estimate the maximum distance to the Moon using the method similar to the Aristarchus method: 64 Earth radii. This gave him the scale of the entire universe. As a result, it turned out that the stars are located at a distance of about 20 thousand radii of the Earth. Ptolemy also made an attempt to estimate the size of the planets. As a result of a random compensation of a number of errors, the Earth turned out to be a medium-sized body of the Universe, and the stars were approximately the same size as the Sun.

According to Ptolemy, the totality of the ethereal spheres belonging to each of the planets is a rational animated being, where the planet itself plays the role of a brain center; the impulses (emanations) emanating from it set in motion the spheres, which, in turn, carry the planet. Ptolemy gives the following analogy: the brain of a bird sends signals to its body that make the wings move, carrying the bird through the air. At the same time, Ptolemy rejects Aristotle's point of view about the Prime Mover as the reason for the motion of the planets: the celestial spheres move by their own will, and only the outermost of them is set in motion by the Prime Mover.

In late antiquity (starting from the 2nd century AD), there is a significant increase in the influence of Aristotle's physics. A number of comments on the works of Aristotle were compiled (Sosigen, II century AD, Alexander of Aphrodisias, end of II - beginning III century AD e., Simplicius, VI century). There is a revival of interest in the theory of homocentric spheres and attempts to reconcile the theory of epicycles with Aristotelian physics. At the same time, some philosophers expressed a rather critical attitude towards certain postulates of Aristotle, especially his opinion about the existence of the fifth element - ether (Xenarchus, I century AD, Proclus Diadochus, V century, John Philopon, VI century .). Proclus also made a number of criticisms of the theory of epicycles.

Views that went beyond geocentrism also developed. So, Ptolemy discusses with some scientists (without naming them by name), who assume the daily rotation of the Earth. Latin author of the 5th century. n. e. Marcian Capella in writing Marriage of Mercury and Philology describes a system in which the Sun circles the Earth, and Mercury and Venus circle the Sun.

Finally, in the writings of a number of authors of that era, ideas are described that anticipated the ideas of scientists of the New Age. So, one of the participants in Plutarch's dialogue About the face visible on the disk of the moon claims that the moon does not fall to the earth due to the action centrifugal force(like objects put into a sling), "because every object is carried away by its natural movement, if it is not deflected to the side by some other force." In the same dialogue, it is noted that gravity is characteristic not only of the Earth, but also of celestial bodies, including the Sun. The motive could be an analogy between the shape of celestial bodies and the Earth: all these objects are spherical, and since the sphericity of the Earth is associated with its own gravity, it is logical to assume that the sphericity of other bodies in the Universe is associated with the same reason.

Exam abstract

on the topic

"Astronomy

Ancient Greece"

Performed

11th grade student

PerestoroninaMargarita

Teacher

Zhbannikova Tatyana Vladimirovna

Kirov, 2002

IIAstronomyancient Greeks.

1. On the way to truth, through knowledge.

2. Aristotle and the geocentric system of the world.

3. The same Pythagoras.

4. The first heliocentrist.

5. Works of the Alexandrian Astronomers

6. Aristarchus: the perfect method (his true labors and successes; opinions of an eminent scientist; inany theory is a failure, as a consequence) ;

7. "Phaenomena"Euclid and the basic elements of the celestial sphere.

8. The brightest"star" of the Alexandrian sky.

9. Calendar and stars of ancient Greece.

IIIConclusion: the role of astronomers in ancient Greece.

... Aristarchus of Samos in his "Proposals" -

admitted that the stars, the sun do not change

its position in space that the earth

moves in a circle around the sun,

located in the center of her path, and that

center of the sphere of fixed stars

coincides with the center of the sun.

Archimedes. Psamit.

The heyday of Greek civilization falls betweenVI century BC and middleII century BC e. Chronologically, it almost coincides with the time of the existence of classical Greece and Hellenism. This time, taking into account several centuries, when the Roman Empire rose, prospered and perished, is called ancient. VII-II century BC, when the policies-Greek city-states were rapidly developing. This form of government became a hallmark of the Greek world.

The development of the knowledge of the Greeks has no analogues in the history of that time. The scale of comprehension of sciences can be imagined at least by the fact that in less than three centuries (!) Greek mathematics has gone its way from Pythagoras to Euclid, Greek astronomy from Thales to Euclid, Greek natural science from Anaximandrado to Aristotle and Theophrastus, Greek geography from Hekkateya of Miletus before Eratosthenes and Hipparchus, etc.

The discovery of new lands, land or sea voyages, military campaigns, overpopulation in fertile areas - all this was often mythologized. In the poems, with the artistic skill inherent in the Greeks, the mythical side by side with the real. They set out scientific knowledge, information about the nature of things, as well as geographical data. However, the latter are sometimes difficult to identify with today's ideas. And, nevertheless, they are an indicator of the broad views of the Greeks on the ecumene.

The Greeks paid great attention specifically to the geographical knowledge of the Earth. Even during military campaigns, they did not leave the desire to write down everything that they saw in the conquered countries. In the troops of Alexander the Great, even special pedometers were allocated, which counted the distances traveled, made a description of the routes of movement and put them on the map. On the basis of the data they received, Dicaearchus, a student of the famous Aristotle, compiled a detailed map of the ecumene of that time, according to his idea.

... The simplest cartographic drawings were known even in primitive society, long before the advent of writing. This can be judged by rock paintings. The first cards appeared in ancient Egypt. Contours of individual territories with the designation of some objects were applied on clay tablets. Not later than 1700 don. e. The Egyptians made a map of the developed two thousand-kilometer part of the Nile.

The Babylonians, Assyrians and other peoples of the Ancient East were also engaged in mapping the area ...

What did the Earth look like? What place did they assign to themselves on it? What were their ideas about the ecumene?

Astronomy of the ancient Greeks

In Greek science, the opinion was firmly established (with various variations, of course) that the Earth is like a flat or convex disk surrounded by an ocean. Many Greek thinkers did not abandon this point of view even when, in the era of Plato and Aristotle, the ideas about the sphericity of the Earth seemed to prevail. Alas, already in those distant times, the progressive idea made its way with great difficulty, demanded sacrifices from its supporters, but, fortunately, then “talent did not seem like heresy”, and “there was no boot in arguments”.

The idea of ​​a disc (drum or even a cylinder) was very handy in confirming the widely held belief that Hellas was in the middle. It was also quite acceptable for depicting land floating in the ocean.

Within the disk-shaped (and later spherical) Earth, ecumene stood out. Which in ancient Greek means the whole inhabited earth, the universe. The designation by one word of two seemingly different concepts (for the Greeks then they seemed to be of the same ordinal) is deeply symptomatic.

About Pythagoras (VIcentury BC) little reliable information has been preserved. It is known that he was born on the island of Samos.; probably visited Miletus as a young man, where he studied with Anaximander; may have traveled further afield. Already in adulthood, the philosopher moved to the city of Croton and founded there something like a religious dress - the Pythagorean brotherhood, which extended its influence to many Greek cities in southern Italy. The life of the brotherhood was surrounded by mystery. There were legends about its founder Pythagoras, which, apparently, had some basis: the great scientist was no less a great politician and seer.

The basis of the teachings of Pythagoras was the belief in the transmigration of souls and the harmonious arrangement of the world. He believed that music and mental labor cleanse the soul, so the Pythagoreans considered perfection in “ four arts” - arithmetic, music, geometry and astronomy. Pythagoras himself is the founder of number theory, and the theorem he proved is known today to every schoolchild. And if Anaxagoras and Democritus in their views of the world developed Anaximander's idea of ​​the physical causes of natural phenomena, then Pythagoras shared his conviction in the mathematical harmony of the cosmos.

The Pythagoreans ruled in the Greek cities of Italy for several decades, then they were defeated and moved away from politics. However, much of what Pythagoras breathed into them remained alive and had a huge impact on science. Now it is very difficult to separate the contribution of Pythagoras himself from the achievements of his followers. This applies in particular to astronomy, in which several fundamentally new ideas have been put forward. They can be judged by the meager information that has come down to us about the ideas of the late Pythagoreans and the teachings of philosophers who were influenced by the ideas of Pythagoras.

Aristotle was born in the Macedonian city of Stagira in the family of a court physician. At the age of seventeen, he ends up in Athens, where he becomes a student of the Academy founded by the philosopher Plato.

At first, Aristotle was fascinated by Plato's system, but gradually he came to the conclusion that the views of the teacher lead away from the truth. And then Aristotle left the Academy, throwing the famous phrase: ” Plato is my friend but the truth is dearer". Emperor Philip of Macedon invites Aristotle to become the tutor of the heir to the throne. The philosopher agrees and for three years he has been near the future founder of the great empire, Alexander the Great. At the age of sixteen, his disciple led his father's army and, having defeated the Thebans in his first battle of Chaeronea, went on campaigns.

Again, Aristotle moves to Athens, and in one of the districts, called Lyceum, he opens a school. He writes a lot. His writings are so varied that it is difficult to imagine Aristotle as a solitary thinker. Most likely, in these years he acted as the head of a large school, where students worked under his leadership, just as today graduate students develop topics that their leaders offer them.

The Greek philosopher paid much attention to questions of the structure of the world. Aristotle was convinced that at the center of the universe, of course, is the Earth.

Aristotle tried to explain everything with reasons that are close to the common sense of the observer. So, observing the Moon, he noticed that in various phases it exactly corresponds to the form that a ball would take, on one side illuminated by the Sun. Equally rigorous and logical was his proof that the earth was spherical. After discussing all the possible reasons for the eclipse of the moon, Aristotle comes to the conclusion that the shadow on its surface can only belong to the Earth. And since the shadow is round, the body casting it must have the same shape. But Aristotle is not limited to them. “Why,” he asks, “when we move north or south, do the constellations change their positions relative to the horizon? ”And then he replies:“Because the earth has a curvature". Indeed, if the Earth were flat, wherever the observer was, the same constellations would shine over his head. It is quite another thing - on a round Earth. Here, each observer has his own horizon, his own horizon, his own sky… However, recognizing the sphericity of the Earth, Aristotle categorically spoke out against the possibility of its circulation around the Sun. “Be it so,” he reasoned, “it would seem to us that the stars are not motionless on the celestial sphere, but describe circles ...” This was a serious objection, perhaps the most serious, which was eliminated only many, many centuries later, in the XIX century.

Much has been written about Aristotle. The authority of this philosopher is incredibly high. And it is well deserved. Because, despite the rather numerous errors of delusion, in his writings Aristotle collected everything that the mind had achieved during the period of ancient civilization. His writings are a real encyclopedia of contemporary science.

According to contemporaries, the great philosopher was distinguished by an unimportant character. The portrait that has come down to us presents us with a short, lean man with a candle-stinging grin on his lips.

Onkorta spoke.

In relations with people he was cold and arrogant.

But few dared to enter into an argument with him. The witty, angry and mocking speech of Aristotle struck on the spot. He smashed the arguments raised against him deftly, logically and cruelly, which, of course, did not add to his supporters among the vanquished.

After the death of Alexander the Great, the offended finally felt a real opportunity to get even with the philosopher and accused him of godlessness. The fate of Aristotle was sealed. Without waiting for the verdict, Aristotle flees from Athens. “To rid the Athenians of a new crime against philosophy,” he says, alluding to the similar fate of Socrates, who received a cup of poisonous hemlock juice by sentence.

After leaving Athens for Asia Minor, Aristotle soon dies, having poisoned himself during a meal. So says the legend.

According to legend, Aristotle bequeathed his manuscripts to one of his students named Theophrastus.

After the death of a philosopher, a real hunt begins for his works. In those years, books themselves were a treasure. The books of Aristotle were valued more than gold. They passed from hand to hand. They were hidden in the cellars. Walled up in cellars to save from the greed of the Pergamon kings. Dampness spoiled their pages. Already under Roman rule, the writings of Aristotle, as spoils of war, fall into Rome. Here they are sold to amateurs - the rich. Some people try to restore the damaged parts of the manuscripts, to supply them with their own additions, which, of course, does not make the text better.

Why were the works of Aristotle so valued? Indeed, in the books of other Greek philosophers, thoughts were more original. This question is answered by the English philosopher and physicist John Bernal. Here is what he writes: ” Nobody could understand them (ancient Greek thinkers), except for very well trained and sophisticated readers. And the works of Aristotle, for all their cumbersomeness, did not require (or did not seem to require) for their understanding anything but common sense ... To verify his observations, there was no need for experiments or instruments, difficult mathematical calculations or mystical intuition were not needed to understand any whatever the inner meaning ... Aristotle explained that the world is the way everyone knows it, exactly the way they know it ”.

Time will pass, and the authority of Aristotle will become unconditional. If in a dispute one philosopher, confirming his arguments, refers to his works, this will mean that the arguments are certainly correct. And then the second disputant must find in the writings of the same Aristotle another quotation, with the help of which it is possible to refute the first one. ... Only Aristotle against Aristotle. But many centuries had to pass before people understood this and rose to fight deathly scholasticism and dogmatism. This struggle revived the sciences, revived art and gave the name of the era - the Renaissance.

In ancient times, the question of whether the Earth moves around the Sun was simply blasphemous. Both famous scientists and ordinary people, for whom the picture of the sky did not cause much thought, were sincerely convinced that the Earth is motionless and represents the center of the Universe. However, modern historians can name at least one ancient scientist who challenged the conventional wisdom and tried to develop a theory that the earth moves around the sun.

The life of Aristarchus of Samos (310 - 250 BC) was closely connected with the Library of Alexandria. Information about him is very scarce, and only the book "On the Sizes of the Sun and the Moon and the Distances to Them", written in 265 BC Only mentions of him by other scientists of the Alexandrian school, and later by the Romans, shed some light on his "blasphemous" scientific research.

Aristarchus wondered how far from the Earth to the celestial bodies, and what are their sizes. Before him, the Pythagoreans tried to answer this question, but they proceeded from arbitrary proposals. So, Philolaus believed that the distances between the planets and the Earth are growing exponentially and each next planet is three times farther from the Earth than the previous one.

Aristarchus went his own way, completely correct from the point of view of modern science. He closely followed the moon and its changing phases. At the moment of the onset of the first quarter phase, he measured the angle between the Moon, the Earth and the Sun (the LOS angle in the figure). If this is done accurately enough, then only calculations will remain in the problem. At this moment, the Earth, Moon and Sun form a right triangle, and, as is known from geometry, the sum of the angles in it is 180 degrees. In this case, the second acute angle of the Earth - the Sun - the Moon (the angle of the ZSL) is equal to

90˚ -Ð LZS= Ð ZSL

/>
Determination of the distance from the Earth to the Moon and the Sun by the method of Aristarchus.

Aristarchus, from his measurements and calculations, obtained that this angle is 3º (in fact, its value is 10’ ) and that the Sun is 19 times farther from the Earth than the Moon (actually 400 times). Here we must forgive the scientist for a significant mistake, because the method was absolutely correct, but the inaccuracies in measuring the angle turned out to be great. It was difficult to accurately capture the moment of the first quarter, and the ancient measuring instruments themselves were far from perfect.

But this was only the first success of the remarkable astronomer Aristarchus of Samos. It fell to him to observe a total solar eclipse when the disk of the Moon covered the disk of the Sun, i.e. the apparent sizes of both bodies in the sky were the same. Aristarchus rummaged through the old archives, where he found a lot of additional information about eclipses. It turned out that in some cases solar eclipses were annular, that is, a small luminous rim from the Sun remained around the disk of the Moon (the presence of total and annular eclipses is due to the fact that the Moon's orbit around the Earth is an ellipse). But if the visible disks of the Sun and the Moon in the sky are almost the same, Aristarchus argued, and the Sun is 19 times farther from the Earth than the Moon, then its diameter should be 19 times larger. What is the relationship between the diameters of the Sun and the Earth? According to many data on lunar eclipses, Aristarchus established that the lunar diameter is approximately one third of the earth's and, therefore, the latter should be 6.5 times smaller than the solar one. At the same time, the volume of the Sun should be 300 times the volume of the Earth. All these considerations distinguish Aristarchus of Samos as an outstanding scientist of his time.

body" of Aristotle. But can the huge Sun revolve around the small Earth? Or even more huge All -

lazy? And Aristotle said, no, he can't. The sun is the center of the universe, the earth and planets revolve around it, and only the moon revolves around the earth.

Why does day turn into night on Earth? And Aristarchus gave the correct answer to this question - the Earth not only revolves around the Sun, but also rotates around its axis.

And he answered one more question perfectly. Let us give an example with a moving train, when external objects close to the passenger run past the window faster than distant ones. The earth moves around the sun, but why does the star pattern stay the same? Aristotle replied: "Because the stars are unimaginably far from the small Earth." The volume of the sphere of fixed stars is as many times greater than the volume of a sphere with a radius of the Earth - the Sun, how many times the volume of the latter is greater than the volume of the globe.

This new theory was called heliocentric, and its essence was that the motionless Sun was placed at the center of the universe and the sphere of stars was also considered motionless. Archimedes in his book “Psamit”, an excerpt from which is given as an epigraph to this essay, accurately conveyed everything that Aristarchus proposed, but he himself preferred to “return” the Earth to its old place again. Other scientists have completely rejected the theory of Aristarchus as implausible, and the idealist philosopher Cleanthes simply accused him of blasphemy. The ideas of the great astronomer did not find the ground for further development at that time, they determined the development of science for about one and a half thousand years and then revived only in the works of the Polish scientist Nicolaus Copernicus.

The ancient Greeks believed that poetry, music, painting and science were patronized by nine muses, who were the daughters of Mnemosyne and Zeus. So, the muse Urania patronized astronomy and was depicted with a crown of stars and a scroll in her hands. Clio was considered the muse of history, Terpsichore was the muse of dances, Melpomene was the muse of tragedies, etc. The Muses were the companions of the god Apollo, and their temple was called the museum - the house of the muses. Such temples were built both in the metropolis and in the colonies, but the Alexandria Museum became an outstanding academy sciences and arts of the ancient world.

Ptolemy Lag, being a persistent man and wanting to leave a memory of himself in history, not only strengthened the state, but also turned the capital into a trading center for the entire Mediterranean, and the Museum into a scientific center of the Hellenistic era. The huge building housed a library, a higher school, an astronomical observatory, a medical anatomical school, and a number of scientific departments. The museum was a public institution, and its expenses provided -

fell under the corresponding budget item. Ptolemy, like Ashurbanipal in Babylon in his time, sent out clerks throughout the country to collect cultural treasures. In addition, each ship entering the port of Alexandria was obliged to transfer to the library the literary works on board. Scientists from other countries considered it an honor to work in the scientific institutions of the Museum and leave their work here. For four centuries, the astronomers Aristarchus of Samos and Hipparchus, the physicist and engineer Heron, the mathematicians Euclid and Archimedes, the doctor Herophilus, the astronomer and geographer Claudius Ptolemy and Eratosthenes worked in Alexandria, who with equal success understood mathematics, geography, astronomy, and philosophy.

But the latter was already rather an exception, since an important feature of the Hellenic era was the "differentiation" of scientific activity. Here it is curious to note that such a separation of individual sciences, and in astronomy and specialization in certain areas, occurred in ancient China much earlier.

Another feature of Hellenic science was that it again turned to nature, that is, it began to "extract" the facts itself. The Encyclopedists of Ancient Hellas relied on the information obtained by the Egyptians and Babylonians, and therefore were engaged only in the search for the causes that cause certain phenomena. The science of Democritus, Anaxagoras, Plato and Aristotle was even more speculative, although their theories can be regarded as the first serious attempts of mankind to understand the structure of nature and the entire Universe. The Alexandrian astronomers closely followed the movements of the Moon, the planets, the Sun, and the stars. The complexity of planetary movements and the richness of the stellar world forced them to look for starting points from which systematic research could begin.

« Phaenomena» Euclid and the basic elements of the celestial sphere

As mentioned above, the Alexandrian astronomers tried to determine the "starting" points for further systematic research. In this regard, special merit belongs to the mathematician Euclid ( IIIin. BC BC), who in his bookPhaenomena"For the first time introduced the concept of gastronomy, until then it had not been used in it. So, he gave definitions of the horizon - a great circle, which is the intersection of a plane perpendicular to the plumb line at the point of observation, with the celestial sphere, as well as the celestial equator - a circle resulting from the intersection with this sphere of the plane of the earth's equator.

In addition, he determined the zenith - the point of the celestial sphere above the observer's head ("zenith" is an Arabic word) - the point opposite to the zenith point - nadir.

And Euclid spoke about one more circle. This is heaven -

ny meridian - a large circle passing through the Pole of the world and the zenith. It is formed when it intersects with the celestial sphere a plane passing through the axis of the world (axis of rotation) and a plumb line (i.e., a plane perpendicular to the plane of the earth's equator). Refer -

Regarding the value of the meridian, Euclid said that when the Sun crosses the meridian, it is noon in this place and the shadows of objects are the shortest. To the east of this place, noon on the globe has already passed, but to the west it has not yet arrived. As we remember, the principle of measuring the shadow of a gnomon on Earth for many centuries underlay the design of sundials.

The brightest "star" of the Alexandrian sky.

Previously, we have already become acquainted with the results of the activities of many astronomers, both well-known and those

whose names have sunk into oblivion. Even thirty centuries before the new era, Heliopolis astronomers in Egypt established the length of the year with amazing accuracy. Curly-bearded priests - astronomers who observed the sky from the tops of the Babylonian ziggurats, were able to draw the path of the Sun among the constellations - the ecliptic, as well as the celestial paths of the Moon and stars. In distant and mysterious China, the inclination of the ecliptic to the celestial equator was measured with high accuracy.

Ancient Greek philosophers sowed seeds of doubt about the divine origin of the world. Under Aristarchus, Euclid and Eratosthenes, astronomy, which until then had given most of astrology, began to systematize its studies, standing on the firm ground of true knowledge.

And yet, what Hipparchus did about the field of astronomy far exceeds the achievements of both his predecessors and scientists of a later time. For good reason, Hipparchus is called the father of scientific astronomy. He was extremely punctual in his research, repeatedly checking the conclusions with new observations and striving to discover the essence of the phenomena occurring in the Universe.

The history of science does not know where and when Hipparchus was born;It is only known that the most fruitful period of his life falls on the time between 160 and 125 AD. BC e.

He spent most of his research at the Alexandria Observatory, as well as at his own observatory built on the island of Samos.

Even before the Hipparchatheories of the celestial spheres of Eudoxus and Aristotle, they were rethought, in particular, by the great Alexandrian mathematician Apollonius of Perga (III in. BC BC), but the Earth still remained at the center of the orbits of all celestial bodies.

Hipparchus continued the development of the theory of circular orbits begun by Apollonius, but made significant additions to it, based on long-term observations. Earlier, Calippus, a student of Eudoxus, discovered that the seasons were not of the same length. Hipparchus checked this statement and clarified that the astronomical spring lasts 94 and ½ days, summer - 94 and ½ days, autumn - 88 days and, finally, winter lasts 90 days. Thus, the time interval between the spring and autumn equinoxes (including summer) is 187 days, and the interval from the autumn equinox to the spring equinox (including winter) is 88 + 90 = 178 days. Consequently, the Sun moves unevenly along the ecliptic - slower in summer and faster in winter. Another explanation of the reason for the difference is possible, if we assume that the orbit is not a circle, but “ elongated”a closed curve (Appolonius of Perga called it an ellipse). However, to accept the uneven movement of the Sun and the difference of the orbit from a circular one meant to turn upside down all the ideas that had been established since the time of Plato. Therefore, Hipparchus introduced a system of eccentric circles, assuming that the Sun revolves around the Earth in a circular orbit, but the Earth itself is not located in its center. The unevenness in this case is only apparent, because if the Sun is closer, then the impression of its faster movement arises, and vice versa.

However, for Hipparchus, the direct and backward movements of the planets, i.e. the origin of the loops that the planets described in the sky, remained a mystery. Changes in the visible brightness of the planets (especially for Mars and Venus) testified that they, too, move in eccentric orbits, now approaching the Earth, now moving away from it and changing brightness accordingly. But what is the reason for the straight and backward movements? Hipparchus came to the conclusion that placing the Earth away from the center of the orbits of the planets is not enough to explain this riddle. Three centuries later, the last of the great Alexandrians, Claudius Ptolemy, noted that Hipparchus abandoned the search for this direction and limited himself to systematizing his own observations and those of his predecessors. It is curious that at the time of Hipparchus there was already in astronomy the concept of an epicycle, the introduction of which is attributed to Apollonius of Perga. But one way or another, Hipparchus did not begin to study the theory of planetary motion.

But he successfully modified the method of Aristarchus, which makes it possible to determine the distance to the Moon and the Sun. The spatial arrangement of the Sun, Earth and Moon during the lunar eclipse when observations were made.

Hipparchus also became famous for his work in the field of stellar research. He, like his predecessors, believed that the sphere of fixed stars really exists, that is, the objects located on it are at the same distance from the Earth. But why then are some of them brighter than others? Therefore, Hipparchus believed that their true sizes are not the same - the larger the star, the brighter it is. He divided the brightness range into six values, from the first for the brightest stars to the sixth for the faintest, still visible to the naked eye (naturally, there were no telescopes then). In the modern scale of stellar magnitudes, a difference of one magnitude corresponds to a difference in radiation intensity of 2.5 times.

In 134 BC, a new star shone in the constellation Scorpio (now it is established that new stars are binary systems in which an explosion of matter occurs on the surface of one of the components, accompanied by a rapid increase in the object's blackness, followed by fading). Previously, there was nothing at this place , and therefore Hipparchus came to the conclusion that it was necessary to create an accurate star catalog. With extraordinary care, the great astronomer measured the ecliptic coordinates of about 1000 stars, and also estimated their magnitudes on his own scale.

While doing this work, he decided to test the opinion that the stars are fixed. More precisely, descendants should have done it. Hipparchus compiled a list of stars located on one straight line, in the hope that future generations of astronomers would check whether this line remained straight.

While compiling the catalog, Hipparchus made a remarkable discovery. He compared his results with the coordinates of a number of stars measured before him by Aristylus and Timocharis (contemporaries of Aristarchus of Samos), and found that the ecliptic longitudes of objects increased by about 2º over 150 years. At the same time, the ecliptic latitudes have not changed. It became clear that the reason was not in the proper motions of the stars, otherwise both coordinates would have changed, but in the displacement of the vernal equinox point, from which the ecliptic longitude is measured, and in the direction opposite to the movement of the Sun along the ecliptic. As you know, the vernal equinox is the intersection of the ecliptic with the celestial equator. Since the ecliptic latitude does not change with modern times, Hipparchus concluded that the reason for the shift of this point is the movement of the equator.

Thus, we have the right to be surprised at the extraordinary consistency and rigor in the scientific research of Hipparchus, as well as their high accuracy. The French scientist Delambre, a well-known researcher of ancient astronomy, described his activities as follows: “When you take a look at all the discoveries and improvements of Hipparchus, reflect on the number of his works and the many calculations given there, willy-nilly you will attribute him to the most outstanding people of antiquity and, moreover, you will call him the greatest among them. . Everything he achieved belongs to the field of science, where geometric knowledge is required, combined with an understanding of the essence of phenomena that can be observed only if tools are carefully made ... ”

star calendars

In ancient Greece, as in the countries of the East, the lunar-solar calendar was used as a religious and civil one. In it, the beginning of each calendar month should have been located as close as possible to the new moon, and the average duration of the calendar year should, if possible, correspond to the time interval between the spring equinoxes (“ tropical year", as it is now called). At the same time, months of 30 and 29 days alternated. But 12 lunar months are about a third of a month shorter than a year. Therefore, in order to fulfill the second requirement, from time to time it was necessary to resort to intercalations - to add an additional, thirteenth, month in some years.

Inserts were made irregularly by the government of each policy - the city-state. For this, special persons were appointed who monitored the magnitude of the lag of the calendar year from the solar year. In Greece, divided into small states, calendars had a local meaning - there were about 400 names of months in the Greek world. The mathematician and musicologist Aristoxenus (354-300 BC) wrote about the calendar disorder: ” The tenth day of the month for the Corinthians is the fifth day for the Athenians the eighth for anyone else”

A simple italic, 19-year cycle, which was used back in Babylon, was proposed in 433 BC. Athenian astronomer Meton. This cycle included the insertion of seven additional months in 19 years; his error did not exceed two hours per cycle.

Farmers connected with seasonal work from ancient times also used the stellar calendar, which was independent of the complex movements of the Sun and Moon. Hesiod in the Poem “ Works and days”, indicating to his brother Persian the time of agricultural work, he marks them not according to the lunisolar calendar, but according to the stars:

Only in the east will they begin to rise

Atlantis Pleiades,

Hurry up and start

Come in, sow, accept ...

That's high in the sky already Sirius

Got up with Orion,

Zarya rose-fingered

see Arthur,

Cut, O Persian, and take home

Grapes…

Thus, a good knowledge of the starry sky, which few people in the modern world can boast of, was necessary for the ancient Greeks and, apparently, widespread. Apparently, this science was taught to children in families from an early age. The lunisolar calendar was also used in Rome. But even greater “calendar arbitrariness” reigned here. The length and beginning of the year depended on the pontiffs (otlat. Pontifices), Roman priests, who often used their right for selfish purposes. Such a situation could not satisfy the huge empire into which the Roman state was rapidly turning. In 46 BC Julius Caesar (100-44 BC), who acted not only as head of state, but also as high priest, carried out a calendar reform. The new calendar, on his behalf, was developed by the Alexandrian mathematician and astronomer Sosigen, a Greek by birth. He took the Egyptian, purely solar, calendar as a basis. The refusal to take into account the lunar phases made it possible to make the calendar quite simple and accurate. This calendar, called the Julian, was used in the Christian world before being introduced in Catholic countries in XVIcentury of the revised Gregorian calendar.

The chronology of the Julian calendar began in 45 BC The beginning of the year was moved to January 1 (earlier the first month was March). In gratitude for the introduction of the calendar, the Senate decided to rename the month quintilis (fifth), in which Caesar was born, into Julius - our July. In 8 BC the honor of the next emperor, Octivian Augustus, the month of sextilis (sixth), was renamed August. When Tiberius, the third princeps (emperor), was proposed by the senators to name the month Septembre (seventh), he allegedly refused, answering: “What will the thirteenth princeps do?”

The new calendar turned out to be purely civil, religious holidays, by virtue of tradition, were still celebrated in accordance with the phases of the moon. And at present, the Easter holiday is consistent with the lunar calendar, and the cycle proposed by Meton is used to calculate its date.

Conclusion

In the distant Middle Ages, Bernard of Chartres spoke golden words to his students: “We are like dwarfs sitting on the shoulders of giants; we see more and farther than them, not because we have better eyesight, and not because we are higher than them, but because they raised us and increased our stature with their greatness. Astronomers of all epochs have always leaned on the shoulders of previous giants.

Ancient astronomy occupies a special place in the history of science. It was in ancient Greece that the foundations of modern scientific thinking were laid. For seven and a half centuries from Thales and Anaximander, who took the first steps in understanding the Universe, to Claudius Ptolemy, who created the mathematical theory of the movement of the stars, ancient scientists have come a long way, on which they had no predecessors. Astronomers of antiquity used data obtained long before them in Babylon. However, for their processing, they created completely new mathematical methods, which were adopted by medieval Arab and later European astronomers.

In 1922, the International Astronomical Congress approved 88 international names for the constellations, thereby perpetuating the memory of the ancient Greek myths, after which the constellations were named: Perseus, Andromeda, Hercules, etc. (about 50 constellations). The meaning of ancient Greek science is emphasized by the words: planet, comet, galaxy and self-word Astronomy.

List of used literature

1. “ Encyclopedia for children".Astronomy. (M. Aksenova, V. Tsvetkov, A. Zasov, 1997)

2. “ Stargazers of antiquity". (N. Nikolov, V. Kharalampiev, 1991)

3. “ Discovery of the universe - past, present, future". (A. Potupa, 1991)

4. “ Horizons of the ecumene". (Yu. Gladky, Al. Grigoriev, V. Yagya, 1990)

5. Astronomy, 11th grade. (E. Levitan, 1994)

Abstract protection plan

Agree, today a person, in whatever remote area of ​​science or the national economy he works, must have an idea, at least a general one, about our solar system, stars and modern achievements in astronomy.

Humanity is not yet clear about the conditions that led to the formation of various natural complexes, including those that favored the origin and development of life on Earth. Most of these questions are answered by the science of astronomy. This report will focus on the origin of this ancient science, its practical significance.

I chose this topic because the mysterious world of the formation of stars and planets has attracted the attention of people since ancient times. This topic has been relevant for thousands of years, and only in the last 10 years have reliable data been obtained on the presence of planets and planetary systems in other stars. The knowledge of planets and planetary systems will lead mankind to the solution of another global problem - the existence of life on planets, and this will be solved by mankind only in the third millennium.

The objectives of the work are: to study the history of the emergence of astronomy, to trace the stages of its formation; meet the first astronomers; find out and describe the first ancient observatories, compile a comparative table of the length of the sidereal day.

This year, for the first time at school, we began to study the history of our earth, planets and stars. This subject interested me very much, and therefore I turned to this topic.

When writing the work, the material of encyclopedias, astronomical Internet sites, astronomical dictionaries, and periodicals was used.

The structure of the work: the first part deals with the origin of astronomy and its original meaning; in the second part, questions of the construction of the most ancient observatories are raised.

1. Astronomy as a science, its original meaning.

Astronomy is the most ancient among the natural sciences, translated from Greek (Greek αστροννομος, from αστρον - star, νομος - law) the science of the location, structure, properties, origin, movement and development of cosmic bodies (stars, planets, meteorites, etc.). etc.) the systems formed by them (star clusters, galaxies, etc.) and the entire Universe as a whole. One of the outstanding astronomers of antiquity - Ptolemy, the author of the encyclopedia of ancient astronomy, "Almagest", - explained the reasons for the motivation to study astronomy, which he considered part of mathematics: us to engage with all diligence in this excellent science, especially in that branch of it which concerns the knowledge of the divine heavenly bodies, since this science alone is devoted to the study of the eternally unchanging world "

Astronomy, like all other sciences, arose from the practical needs of man. Copernicus also wrote about the connection of observations of celestial bodies with practical life and their influence on social processes: the need to calculate the periods of rise and fall of the water in the Nile created Egyptian astronomy, and at the same time the dominance of the caste of priests as leaders of agriculture. Usually two reasons for the emergence of this science are named: the need to navigate the terrain and the regulation of agricultural work. 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). 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, the authorities expected a return not only in the form of the glory of the patrons of science, but also in the form of astrological predictions. The first records of astronomical observations, the authenticity of which is beyond doubt, date back to the 8th century. BC e.

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. Astronomical knowledge was characteristic of many ancient peoples.

2. Astronomy in ancient Egypt.

It is known that as early as 3 thousand years BC. e. the Egyptians had already invented the Egyptian calendars: lunar-stellar - religious and schematic - civil.

The inhabitants of the Nile Valley, where there is no real winter, divided the year into three seasons, which depended on the behavior of the river. From the Nile, on which the whole life of the Egyptians depended, the astronomy of this ancient civilization began.

By that time in Egypt there was a lunar calendar of 12 months of 29 or 30 days - from new moon to new moon. In order for its months to correspond to the seasons of the year, a thirteenth month had to be added every two or three years. Sirius "helped" to determine the time of this month's insertion. Such an "observant" calendar with an irregular addition of a month was ill-suited for a state where strict accounting and order existed. Therefore, the so-called schematic calendar was introduced for administrative and civil needs. In it, the year was divided into 12 months of 30 days, with the addition of an additional five days at the end of the year.

Ancient Egypt had a complex mythology with many gods. The astronomical conceptions of the Egyptians were closely connected with it.

At Karnak, near Thebes, the oldest Egyptian water clock was found. They were made in the 14th century. BC e. The main sundial in Egypt were, of course, the obelisks dedicated to the Sun-Ra. Such an astronomical device in the form of a vertical column is called a gnomon. The ancient Egyptians, like all nations, divided the sky into constellations. A total of 45 are known. The Egyptians have known the planets since ancient times. It would seem that Egyptian astronomy cannot boast of special achievements. The Egyptians, a sedentary people who lived in a narrow river valley, did not need astronomical methods of orientation. The timing of agricultural work was prompted by the river to the Egyptians, and it was enough to establish the moment of the beginning of its flood, so that, without looking at the sky, to know what would happen next. The priests observed the stars mainly to measure night time, and the scribes introduced a simplified calendar that was not tied to the seasons and, as it were, neglected astronomy. Nevertheless, it was on Egyptian soil, in Alexandria, that Greek scientists later worked, who laid the foundations of modern astronomy. Aristarchus of Samos, Timocharis, Eratosthenes worked here, it was here that Claudius Ptolemy wrote his famous astronomical work. The schematic calendar did not follow the seasons, but it served as an ideal uniform scale for determining the intervals between eclipses observed many years after each other. It was this calendar that Ptolemy used in his calculations, and later Copernicus himself.

3. Astronomical knowledge of the Maya.

For the Maya (the beginning of the Maya civilization dates back to the 2nd millennium BC), astronomy was not an abstract science. In the conditions of the tropics, where there are no seasons sharply marked by nature, and the length of day and night remains almost unchanged, astronomy served practical purposes. Thanks to their astronomical knowledge, the priests were able to calculate the duration solar year: 365.2420 days! In other words, the calendar used by the ancient Maya is more accurate than our modern one by 0.0001 days! The year was divided into eighteen months; each corresponded to certain agricultural work: finding a new site, felling the forest, burning it, sowing early and late varieties maize, bending the cobs to protect them from rain and birds, harvesting and even storing the grains in storage. The Mayan reckoning was carried out from a certain mythical zero date. It corresponds, as modern scientists have calculated, to 5041 738 BC! The starting date of the Mayan chronology is also known, but it should also undoubtedly be classified as legendary - this is 3113 BC. Over the years, the Mayan calendar became more and more complex. More and more it lost its original meaning as a practical guide to agriculture, until finally, in the hands of the priests, it turned into a formidable and very effective tool of a gloomy and cruel religion.

4. The development of astronomy in the Middle East (Ancient China).

An important role is played by the origin of ancient Chinese astronomy, which underlies the astronomical knowledge of the entire Far East. In ancient China, 2000 years BC. e. the apparent movements of the sun and moon were so well understood that Chinese astronomers could predict the onset of solar and lunar eclipses. In the development of ancient Chinese astronomy, a smooth evolutionary course is observed. This move can be divided into the following periods:

1) The introduction of the solar calendar during the time of the legendary Emperor Yao, whose reign the Chinese attribute to the 24th century. BC e.

2) The introduction of a system of 28 lunar stations (houses), approximately at the beginning of the Zhou dynasty, that is, in the XIII century. BC e.

3) The introduction of the gnomon tu-gui, near the middle of the period covered by the Spring and Autumn records to observe the exact epoch of the solstice.

4) Development of a solid calendar system of the Zhuanyu Calendar (Zhuan-yu li) at this time; observation of 5 planets; the basis of the theory of the Five Elements (Wu-xing sho): wood (mu), fire (ho), earth (tu), metal (jin), water (shui), the combination of which determines everything in space. The beginning of systematic observations of the stars.

5) Adoption of the first official system - the Great First Calendar (Tai-chu Li) in 104 BC. e. It was the first system officially recognized by the Chinese government.

5. The development of astronomy in Ancient Greece.

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 of Nicaea (2nd century BC), created the geometric theory of epicycles, which formed the basis of the geocentric system of the world of Ptolemy (2nd 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. Hipparchus compiled the first star catalog in Europe, which included the exact coordinates of about a thousand stars. 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 etc.

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). The emerging new class of 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 more simple methods orientation and timing than could be provided by the Ptolemaic system. 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.

III. The oldest observatories in the world.

Stonehenge - "hanging stones".

"The eighth wonder of the world" Stonehenge was erected at the turn of the Stone and Bronze Ages, several centuries before the fall of Homeric Troy. The period of its construction has now been established by radiocarbon dating from the analysis of human remains burned during burial.

Astronomer Gerald Hawkins was able to establish the purpose of Stonehenge. Stonehenge is so old that even in antiquity its true history was forgotten. Greek and Roman authors almost never mention it. Who built Stonehenge? Stonehenge was built between 1900 and 1600 BC. e. , about a thousand years later than the Egyptian pyramids and several centuries before the fall of Troy. It was erected in three stages. The first construction, traces of which can be found, was started around 1900 BC. e. , when, at the end of the Stone Age, people dug a large circular ditch, throwing out the earth in two shafts on both sides of it. Inside, along the perimeter of the shaft, the first builders dug a ring of 56 "Aubrey Holes". The outer rampart, now almost gone, had the shape of an almost regular circle with a diameter of 115 meters. Directly from the inner edge of the moat rose the most imposing chalk component of early Stonehenge, the inner rampart. This dazzling white mound formed a circle with a diameter of 100 meters. Built of hard chalk, it is still clearly visible. The entrance was oriented so that a person standing in the center of the circle and looking through the entrance gap would see the sun rising just to the left of the Heel Stone on the morning of the summer solstice. This stone - perhaps the very first large stone that early builders set at Stonehenge - is 6 meters long, 2.4 meters wide and 2.1 meters thick; at 1.2 m it is buried in the ground, and is estimated at 35 tons. About 1750 B.C. e. The second stage of construction of Stonehenge began. New builders installed the first ensemble of "big stones". At least 82 bluestones were set in two small concentric circles 1.8m apart and about 10.5m from the inner ring. The double circle of blue stones, apparently, should have been composed of radially diverging rays, each including two stones. In 1700 B.C. e. in Britain, the Bronze Age begins, and with it the third phase of the construction of Stonehenge. By the last builders, the double circle, begun in the second period, but not completed, was dismantled. The blue stones were replaced with large sarsen boulders, numbering 81 or more. During this period, apparently, an oval of 20 blue stones was built inside a sarsen horseshoe. Perhaps, at the same time, the “Altar” stone was placed, which was unique in its mineralogical composition. In addition, they installed a ring of blue stones between the sarsen horseshoe and the sarsen ring. And with that, the building was completed.

Many people thought about the astronomical significance of Stonehenge, but could not say anything definite about this. For example, in 1740 John Wood suggested that Stonehenge was "a Druid temple dedicated to the Moon". In 1792, a man known only to call himself Waltyre claimed that Stonehenge was "an enormous theodolite for observing the movement of heavenly bodies, and was erected at least 17,000 years ago." In 1961, J. Hawkins came to the conclusion that "the problem of Stonehenge deserves to be called to the aid of a computer." First of all, programmers Shoshana Rosenthal and Julie Cole took a map of Stonehenge and placed it in the Oscar automatic measuring machine. After "checking" it turned out that the main and often repeated directions of Stonehenge pointed to the Sun and the Moon. Once it is established that the builders oriented Stonehenge to the Sun and Moon with such skill, consistency, and perseverance, the question naturally arises: "Why?" J. Hawkins believes that the solar-lunar directions in Stonehenge were established and noted for two, and maybe four reasons:

1) they served as a calendar, especially useful for predicting the start time of sowing;

2) they contributed to the establishment and preservation of the power of the priests;

3) they served to predict the eclipses of the Moon and the Sun.

Using them to count years, the priests of Stonehenge could follow the movement of the moon and thereby predict "dangerous" periods when the most spectacular eclipses of the moon and sun could occur.

In 2004, during archaeological excavations in the UK, the remains of the builders of Stonehenge with radioactive teeth were discovered. The skeletons of seven men, who are about 4300 years old, were found during construction work near the buildings of Stonehenge. After lengthy research, British archaeologists announced that it was these people who took part in the construction of the famous religious building and were buried about 4300 years ago along with clay vessels and arrowheads. They are four brothers and their three children. While scientists are still arguing whether Stonehenge was a cult building or an ancient observatory, the answer to the question of where the twenty-meter stone blocks of the structure came from has already been found. The most unusual of them, the so-called "blue stones", were brought from the Preseli hills, which are located 250 km from Stonehenge in Wales - the area with the highest natural radioactivity. Scientists examined their tooth enamel and found in it a large number of radioactive strontium. As teeth grow, they accumulate a kind of chemical imprint of the environment.

Ancient observatories in China.

Chinese archaeologists have discovered the world's oldest astronomical observatory, which is estimated to be 4,300 years old. With its help, it was possible to determine the change of seasons with an accuracy of up to a day. The ancient structure was found in the northern province of Shanxi at the site of the settlement of Taos, which existed between 2600 and 1600 BC. Excavations at the archaeological site, carried out on an area of ​​about 3 million square meters near the city of Linfen, revealed to scientists a kind of British "Stonehenge": 13 stone columns 4 meters high, located at a certain distance from each other along a semicircle with a radius of 40 meters. The observatory is at least 2,000 years older than a similar Mayan structure in Central America, said Hi Nu, a researcher at the Institute of Archeology at the Chinese Academy of Social Sciences. According to him, this building, built at the decline of primitive society, "served not only for astronomical observations, but also for the performance of sacrificial rites."

Another ancient observatory in China is located in the southwestern part of the Jianguomen Bridge in Beijing. The ancient observatory was built during the Ming Dynasty (circa 1442 BC) and is one of the oldest observatories in the world. The ancient observatory is also known for its integral structure, excellent precision instrument, long history and special location, and plays an important role in the exchange of Eastern and Western cultures around the world. In the Ming Dynasty, Beijing's ancient observatory was named "Guangxingtai" (stargazing site)

A simple sphere, an armillary sphere, a celestial globe and other large astrological instruments, as well as a gnomon and clepsydra, are installed on the platform.

The height of the observatory building is about 14 meters. The length of its platform from north to south is 20.4 meters, and from west to east - 23.9 meters, 8 astrological instruments were installed there, which were produced during the Qing dynasty.

Until 1929, the Ancient Observatory served as a place for astronomical observations for 500 years, it is considered the oldest observatory where continuous observations made during that period have been preserved.

Observatory Ulugbek.

The development of astronomy in the Middle East is associated with the formation of the Arab Caliphate in the 7th - 8th centuries. As in all other states, astronomy was used at first purely for practical purposes and was used to build numerous mosques, where it was required to determine the qibla - the direction to Mecca, where Muslims directed their gaze during prayer. However, the rapid development and expansion of states required an ever deeper knowledge of mathematics and astronomy, as a result of which astronomical observatories began to be created, in which qualified astronomers and mathematicians worked, and already in the 9th-11th centuries. the level of astronomical research in the Middle East reached great heights. It was here that prominent encyclopedists worked: Muhammad bin-Musa al-Khwarizmi (Algoritmi) (780-850) in the Baghdad observatory, Abu-Raykhan al-Biruni (973-1048), Abu-Ali ibn-Sino (980- 1037), al-Sufi, Omar Khayyam (1040-1123) at the Isfahan Observatory and Nasir-ad-din Tusi (1201-1274) at the Merag Observatory. On this solid foundation, the Samarkand astronomical school arose at the beginning of the 15th century, the ideological and scientific inspirer of which was Ulugbek. Fate destined him the fate of the heir to the throne of a great empire, and natural talent, intelligence and determination opened the way to a scientific feat. Sultan Mohammed Taragai Ulugbek, the son of Shahrukh, was born on March 22, 1394 in the military convoy of his famous grandfather Amir Temur during a stop in the city of Sultania (now it is the territory of Iran). As a child, Ulugbek accompanied his famous grandfather Timur in his aggressive, devastating campaigns. Ulugbek visited Armenia, Afghanistan, accompanied Timur on a campaign against India and China. Ulugbek began to get involved in science in his youth. He spent most of his time in the richest library, where the books collected by his grandfather and father from all over the world were concentrated. Ulugbek loved poetry and history. Ulugbek's teachers were outstanding scientists for whom Timur's court was famous, and among them was the mathematician and astronomer Kazy-zade Rumi. He showed the nine-year-old Ulugbek the ruins of the famous observatory in Maraga, perhaps this was the reason why Ulugbek paid most of his attention to astronomy. The main brainchild of Ulugbek, and perhaps the main goal of his life, was the observatory, which was built in 1428-29 years (832 AH) on a rocky hill at the foot of the Kuhak hill (modern Chupan-Ata) on the banks of the Obirakhmat canal and was a three-story a building covered with fine tiles. Even before the start of construction, an astrolabe with a diameter of one gas (equal to 62 cm) and a star globe were created for astronomical observations. Ulugbek installed a sundial on the wall of his palace. The round building of the observatory had a diameter of 46.4 meters, a height of at least 30 meters and contained a grandiose instrument - a quadrant, on which observations were made of the Sun, Moon and other planets of the celestial vault. In the 60s of the 20th century, the architect V. A. Nielsen tried to reproduce the appearance of the observatory, as it appeared in the era of Ulugbek. The plan of the building itself was very complex, it contained large halls, rooms, corridors. Ulugbek's scientific work "New Guragan astronomical tables" was an outstanding contribution to the treasury of world astronomical science. Among the numerous astronomical tables of Ulugbek, the table of geographical coordinates of 683 different cities not only in Central Asia, but also in Russia, Armenia, Iran, Iraq and even Spain is of great interest. Ulugbek's astronomical works are based on geocentrism, which is quite a natural phenomenon for the medieval era. With amazing accuracy, the length of the sidereal year was calculated. According to Ulugbek, the sidereal year is 365 days 6 hours 10 minutes 8 seconds, and the true length of the sidereal year (according to modern data) is 365 days 6 hours 9 minutes 9.6 seconds. So the error made at that time is less than one minute.

The star catalog of Samarkand astronomers was the second after the catalog of Hipparchus, compiled 17 centuries earlier. Ulugbek's star tables remained the last word of medieval astronomy and the highest level that astronomical science could achieve before the invention of the telescope. That is how great is the significance of many years of painstaking scientific research of Samarkand astronomers of the XIII century. The results of their scientific achievements had a huge impact on the development of science in the West and East, including the development of science in India and China.

Ancient observatory of Europe.

The observatory found in a small place called Goseck near the city of Halle in the federal state of Saxony-Anhalt is a kind of European Stonehenge. This earthwork was a platform with a diameter of 75 meters, where two round wooden fences were located. In three places, passages were made in the fences - gates to the sun. On December 21, on the day of the winter solstice, a bizarre play of sunlight could be observed inside the structure. At sunrise sunlight hit exactly at the eastern gate, and at sunset - directly at the western gate. This design indicates that already 5000 years before the birth of Christ, people tried to find reference points in the sky in order to determine the annual cycles. Until now, scientists did not suspect that prehistoric farmers were capable of this. But the Gozek observatory was used not only for observing the stars and determining the seasons for the needs Agriculture. The construction was also a cult place, because in those days people revered the constellations as gods. This observatory marked the beginning of the creation of a series of similar structures in Europe during the Neolithic and Bronze Ages.

The oldest Eurasian observatory was discovered in Bashkiria.

Chelyabinsk scientists came to the conclusion that an ancient observatory of Eurasia was located near the village of Akhunovo, Uchalinsky district of Bashkiria. The megalithic monument of Akhunovo was discovered back in 1996, but the excavations were completed only this year. As a result of a complex of archaeoastronomical works, it was established that the megalithic complex was built in antiquity as an astronomical observatory. Observations with its help of sunrises and sunsets make it possible to maintain a systematic calendar containing key astronomical dates: the days of the summer and winter solstices. Based on the totality of archaeological and archaeoastronomical data, it can be assumed that it was built in the 3rd millennium BC. e. However, this hypothesis needs further verification. A Late Bronze Age settlement was discovered 70 meters from the megalithic complex.

Ryazan Stonehenge.

Two years ago, Russian archaeologist Ilya Akhmedov made a sensational discovery. In the immediate vicinity of the settlement of Old Ryazan in the town of Spasskaya Luka, an ancient structure was found, similar in structure to the English Stonehenge. Its age is estimated at 4 thousand years. However, unlike its British counterpart, the Ryazan Stonehenge turned out to be smaller in size, moreover, not stone, but wooden. But, according to Akhmedov, the English observatory was also originally made of wood.

Over the next two years, similar discoveries took place almost throughout Eurasia. Ural, Baikal, Chuvashia, Bashkiria, Karelia, Yakutia, Adygeya, Armenia, Kazakhstan, Tajikistan, Germany, Austria Slovakia - far from complete geography of ancient observatories. Moreover, discoveries were made not by amateur researchers, but by pundits. Naturally, each scientist considered it his duty to emphasize that the observatory he discovered was at least a thousand years older than the famous "hanging stones" in England. Archaeological work continues.

Maybe in the coming years we are waiting for new sensations.

Conclusion.

To know the history of our Earth, the Universe, to learn more about the stars, eclipses, planets, mankind wanted from its very appearance. Long before the emergence of the science of astronomy, man noticed various natural phenomena, such as: an eclipse of the sun, the movement of planets, he wondered why rivers flooded.

By the time the science of astronomy emerged, ancient people had accumulated rich practical experience in understanding the world. Astronomy, like all other sciences, arose from the practical needs of man.

Usually two reasons for the emergence of this science are named: the need to navigate the terrain and the regulation of agricultural work. In addition, by investing large sums in the construction of observatories and precision instruments, the authorities expected a return not only in the form of the glory of the patrons of science, but also in the form of astrological predictions.

The first records of astronomical observations, the authenticity of which is beyond doubt, date back to the 8th century. BC e.

Priests actively used knowledge in the field of astronomy, wishing to extend their power to believers.

Observatories were an ancient religious building of antiquity. People watched the sunrise and sunset, tried to calculate the length of the sidereal day and year, made calendars, kept records of the onset of eclipses.

All this knowledge was used by them for practical purposes until the onset of the Middle Ages, when new discoveries made by astronomers made it possible to change man's understanding of the position of the Earth.

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.