The development of ideas about the structure of the world astronomy. Presentation on the topic "structure of the world"
Development of ideas about building peace.
Brinev Vasily Nikolaevich,
teacher MKOU "Troitskaya secondary school"
Korenevsky district, Kursk region.
The idea of the Earth among the ancient Indians.
The earth is flat, located on four elephants, which in turn stand on a huge turtle floating in the water.
The concept of the earth among the Egyptians.
The earth is flat, and the sky is a huge dome spread over the earth. The stars are located on the vault of the dome. The change of the day of the day is the movement of the sun god Ra.
Geocentric system of the world .
In ancient times, it was believed that the Earth is motionless, flat and located in the center of the world. Such a presentation is called anthropocentrism.
Geocentric system of the world .
Pythagoras was the first to express the idea that the Earth has the shape of a ball and is in the Universe without any support.
According to the ideas of the Pythagorean school: in the very center of the Universe is the motionless Earth. Around the Earth revolve, one inside the other, nine spheres. These are the spheres of the Moon, the Sun and the five planets - Mercury, Venus, Mars, Jupiter and Saturn. Farthest away is the stellar sphere.
Geocentric world system.
One of the disciples of Pythagoras, Philolaus, argued that in the center of all spheres there is a central fire, which gives light and heat to all other celestial bodies. The earth, like all planets, revolves with its sphere around this fire. The sun also revolves around fire, but unlike the planets, its smooth, shiny surface reflects its light, transmitting it to the planets.
Geocentric system of the world .
Sun more earth. The moon reflects sunlight. The Milky Way is made up of huge amount stars.
Geocentric world system.
Aristotle suggested that the earth is spherical. The planets are placed on special spheres that revolve around the Earth.
Geocentric system of the world .
Aristarchus of Samos determined the distance to the Moon, calculated the size of the Sun. The earth, along with other planets, revolves around the sun.
Geocentric system of the world.
Claudius Ptolemy developed the geocentric system of the world. The planets move uniformly epicycle- a small circle, the center of which moves around the Earth along deferent- big circle.
Nicolaus Copernicus (1473 - 1543)
Heliocentric system of the world a .
Copernicus showed that the daily motion of all the luminaries can be explained by the rotation of the Earth around its axis, and the loop-like motion of the planets can be explained by the fact that they, including the Earth, revolve around the Sun.
Heliocentric system of the world.
Giordano Bruno believed that our solar system is not the only one in the universe. He believed that all the stars visible in the sky are like the Sun, and that planets revolve around each of them. The universe is infinite and has no center.
Giordano Bruno (1548 - 1600)
Galileo Galilei (1564 - 1642)
Heliocentric system of the world.
Galileo Galilei discovered the phases of Venus. Discovered four satellites of Jupiter, refuting the idea that the Earth is the only center in the world. He discovered and measured the height of mountains on the Moon, observed spots on the Sun. He concluded that no "sphere of fixed stars" exists.
Johannes Kepler (1571 - 1630)
Heliocentric system of the world .
Johannes Kepler established the odds of planetary orbits, as well as the pattern of changes in the speed of the planets as they revolve around the Sun.
Pictures: https://www.google.ru/search
Lesson 8, 9 on calendar-thematic planning.
Lesson objectives:
1) educational: a) the formation of knowledge about the contribution of scientists to the creation of a modern scientific picture of the world, b) the formation of knowledge of information that reflects the value of astronomical science and its results, c) the activation of the cognitive activity of students;
2) developing: a) continue the development of intellectual skills to analyze, compare, compare, highlight the main thing, b) form the skills of self-education, that is, work with various sources of educational information, c) continue the formation of information competence; d) to form the skills of working in groups in the media center of the gymnasium.
3) educational: a) the formation of a scientific worldview based on the introduction of knowledge about the modern scientific picture of the world, b) the spiritual and moral education of students on the basis of basic national values, c) the individual and personal development and education of students, d) the education of the student by the subject, the designer of his education, a full source and organizer of their knowledge.
Type of lesson: a lesson in the formation of new knowledge.
Lesson form: multimedia lesson consisting of two standard lessons of 45 minutes each.
Methods: a) subject integration technology and information technology; b) pedagogy of cooperation; c) the reception of going beyond the scope of their academic subject, the use of poetry, literary works; d) form of work: group.
Equipment: a) a computer class in the media center of the gymnasium b) multimedia equipment: a projector, an interactive whiteboard, a laser pointer, c) sources of information: the Internet, specialized literature on the topic, d) didactic teaching aids: worksheets to create a basis for a new educational material, a list of topics for presentations with a single plan, presentation protection sheets, posters on different systems of the world, e) a teacher's presentation, f) a model of the planetary system and home-made devices of students, g) tablets with the names of students' roles.
The sequence of stages of the lesson:
- Organizational;
- Checking homework;
- Assimilation and consolidation of new knowledge;
- Reflection;
- Information about homework, instruction.
Lesson stage. Time |
Receptions. Methods |
What are the students doing. |
What does a teacher do |
1) organizational | Entry to the lesson: setting to given type work, type of activity, taking into account the work of the whole class in groups. Exit from the lesson: “The lesson is over, all the best to you! Goodbye!". It is important that the phrase always marks the end of the lesson. |
Teacher greeting; report of attendants on absentees Independent division into groups for work in the media center. Selection in groups of responsible persons, conventionally named: a) system administrator |
Greeting students; fixing absent; checking the external condition of the classroom; checking the preparedness of students for the lesson; organization of attention and internal readiness of children for the lesson. Determine the goal: the formation of knowledge about the contribution of scientists to the creation of a modern scientific picture of the world. There is a note on the board: the contribution of scientists to the creation of a modern scientific picture of the world. |
2) homework check | Oral interrogation on a chain. | The answers of the students who are sitting in their seats. If someone finds it difficult to answer, then the right to answer automatically passes to another student sitting next to him. | Organization of an oral survey in a chain. Demonstration of a model of the planetary system, a device for drawing an ellipse. |
3) assimilation and consolidation of new knowledge | Partially search, research teaching methods; heuristic training; independent acquisition of knowledge. Interdisciplinary connections with informatics, literature, poetry. Recordings on the interactive whiteboard. The technique of going beyond the scope of one's subject to create an example of the teacher's morality, the desire to imitate him. | Working with worksheets to create a base for new learning material. They independently decide who submits worksheets from the students of the group for verification. Report of the "information collector" on the progress of work twice for the entire period of the lesson. After the end of the speeches, the comrades hand over the worksheets for verification, taking into account the fact that the grade “excellent” will be given to students who complete any creative task at home. | Instructions on working with worksheets. Introduction to new material through records No. 1, 2, 3, 4 on the interactive whiteboard. Demonstration of posters on different systems of the world. My poems. Task for groups: creation by specific topic presentations from each group using a single outline. Fixation of responsible persons in groups. Conversations with “consultants” of the groups, if necessary, theoretical consultations on the topic. Acceptance for verification of worksheets. |
4) reflection | Recordings on the interactive whiteboard. Cooperation and partnership between teacher and students. Role play elements. | Presentations from each group are presented by a “system administrator”. The “orator” defends the product of the work, proves his point of view, but also accepts, listens to someone else's. Using their supports, they realize the main moral qualities characteristic of all scientists, help to write them down on the interactive whiteboard to the teacher. | Record number 5 on the interactive whiteboard. Participation in viewing presentations from each group. Fixing the protection results in presentation protection sheets. An unsatisfactory rating is not put. Oral assessment product of work for a good emotional atmosphere of the lesson. Phrases like “Great job together!”, “Great answer!”, “Good question!”, “You are very attentive today!”, “Very accurate answer! It was nice to hear from you!” The organization of reflection makes it possible to realize the basic national values in the spiritual and moral education of students. |
5) homework information, briefing | Independent acquisition of knowledge when working with various sources of educational information. The student is the subject, the constructor of his education, the source and organizer of his knowledge. Creating a situation of success for the student. | Mandatory fixation of homework in their notebooks, and not only the traditional assignment, but also the creative assignment. Specific students who create presentations on the topic “F.V. Bessel” receive a plan, but they can change it in agreement with the teacher. Creation by students personal experience in the acquisition of knowledge and the product of their activities; | Homework message: a) traditional assignment: study notes in a notebook and study §8. Make your own notes about F.V. Bessel. b) creative task (optional): 1) find poems about scientists or write your own; 2) create a presentation about F.V. Bessel. Most often, homework is formulated at the beginning of the lesson at the organizational stage of the lesson. |
Applications: No. 1. List of questions for oral questioning by chain.
- How do you understand the expression: “children of the Sun” and “grandchildren of the Sun”? Clarify which bodies belong to them (model of the planetary system, self-made model, drawing of Jupiter).
- Who created the laws that govern the motion of the planets? What are the formulations of these laws (ellipse drawing device).
- Which physical law also valid for celestial bodies? Who is its author?
- What body is at the center of our planetary system? How do we know this?
No. 2. Worksheet to create a base for new learning material.
Surname, name of the student, class _____________________________________________________________________________
Lesson topic: “ Development of ideas about the solar system”
The purpose of the lesson: to consider what is the contribution of scientists to the formation of a modern scientific picture of the world.
Task for the lesson:
- Listen carefully to what your classmates are saying.
- Answer the questions of a single plan in writing (part of the class works in their notebooks) by filling out the table.
Homework:1. Learn notes in a notebook and explore §eight. 2. Make your own notes about F.V. Bessel. 3. creative work(optional): 1) find poems about scientists or write your own; 2) create a presentation about F.V. Bessel.
Number 3. Recordings on the interactive whiteboard.
No. 1. Page 1. “But most of all I was surprised when, quite by chance, it turned out that he had no idea about the theory of Copernicus and about the structure of the solar system. For a civilized person living in the 19th century not to know that the earth revolves around the sun, it seemed so incredible to me ... ”. (John Watson from the work of A.K. Doyle). Photo of the artists who performed the main characters in the Soviet film (Figure 1).
No. 2. Page 2. Development of ideas about the solar system.
- Greek scientist Aristarchus of Samos Italian scientists Nicholas of Cusa and Leonardo da Vinci believed that the Earth revolves around the Sun. Photographs of scientists (Figure 2, 3.4).
Number 3. Page 3. 2. Geocentric system of the world of Ptolemy (2nd century AD) Photograph of a scientist (Figure 5.6)(table on the stand).
No. 5. Page 5.
“A sad fate awaits the one who is endowed with talent, but instead of developing and improving his abilities, he exalts himself excessively and indulges in idleness and self-admiration. Such a person gradually loses the clarity and sharpness of the mind, becomes inert, lazy and overgrown with rust of ignorance, corroding the flesh and soul. (Leonardo da Vinci)
Moral qualities of scientists
(notes in the discussion).No. 4. Poems of own composition.
The sun leads its “children” by the hand, so we call the big planets.
And, of course, he has “grandchildren”. Asteroids, comets, we do not forget.
Many centuries have passed since ancient times, since man saw the world in such a way.
For many famous astronomers, Copernicus was an idol as a scientist.
We will tell you about scientists, how they all developed science.
With their views and boldness of judgments, the scientific world, of course, surprised!
No. 5. Presentation protection sheet.
Group No. _: topic __________________________________________________________
Fig.1 Fig.2
Fig.4Fig.5 Fig.6
63 a common part |
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Subject | Class | Lesson topic |
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astronomy | Development of ideas about the structure of the world |
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Used textbook |
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Name | Class | ||||||||||||||||||||||||||||
Astronomy | B.A. Vorontsov-Velyaminov, E.K. strout |
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Planned educational outcomes |
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subject | Metasubject | Personal |
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reproduce historical information about the formation and development of the heliocentric system of the world, to explain the loop-like motion of the planets using epicycles and trims. | establish cause-and-effect relationships of changing ideas about the structure of the world; characterize the contribution of scientists to the formation of the astronomical picture of the world. | express confidence in the possibility of knowing the system of the world. |
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TCO (equipment) | ICT tools (EFS, programs, applications, Internet resources) |
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Table " solar system”, film "Astronomy" (part 1, fr. 2 "The most ancient science") | Presentation for the lesson |
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Organizational structure lesson |
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Lesson stage | Educational tasks(planned results) | Resources used, incl. EFU (for EFU, specify the names of specific objects and the page) | Teacher activity | Student activities | duration stages (min) |
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Stage 1 Initiation Goal: Creating a positive and comfortable atmosphere, working mood, team building. | Formed communicative competence- the ability to enter into communication, establish contacts between participants. Communicative UUD - the ability to enter into communication, maintain it, which ensures the effectiveness of interaction and work of students in the groups created. | Use the "Let's Travel" method | Hello guys. Today we are spending unusual lesson. Any person, regardless of age, loves to travel. So I suggest you take a trip. The truth is not real, but virtual. And this is a journey into the past. The vehicle will be a time machine. For epigraphs for our lesson, I took the statement of the French writer Antoine Saint-Exupery: “Every person has their own stars. For those who wander, they show the way. For others, it's just lights. For scientists, they are like a problem to be solved.” Before you is a book of reviews and suggestions. Write a slogan or motto that characterizes your team. Write it down in the feedback and suggestions book. | At the entrance to the class, each student chooses a card and goes to the table on which there is a stencil with this card (prepared in advance) - this allows you to form groups. Each table has a guest book. Together, the students will have to come up with a greeting, quote, motto or slogan of their work in the lesson and write it down in the guest book. | 2 minutes |
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Stage 2 Dive into the topic Purpose: Providing motivation for learning and meaningfulness of the learning process | carry out the analysis of objects with the allocation of essential and non-essential features Personal UUD: orientation to the meaningful moments of the educational task Cognitive UUD: activation mental activity students, the inclusion of logical thinking. | Required Materials: Presentation with slides showing questions. Carrying out technology: During the slide show, the groups answer questions, earning points. The team that first raised the signal card answers. If the answer is wrong, then the move goes to the next team. The team that has earned the most points receives a 1st class ticket (this gives the right to be the first to advance on a trip and the right to make two mistakes), other teams receive 2nd class tickets (the right to make 1 mistake) and 3rd class tickets (to make a mistake when no answers). | To start our journey, we need to purchase tickets. To do this, you need to answer the questions (slides 3-9): The orbital period of Saturn around the Sun is about 30 years. Find the time interval between his confrontation. [1/S=1/T h - 1/T , hence S=(1. 30)/(30-1)=1.03 years] Specify the type of configuration in position I, II, VIII. [opposition, inferior conjunction, western elongation] Find the period of revolution of Mars around the Sun, if there is a opposition repeated after 2.1 years. [1/S=1/T h - 1/T , hence T= (Th. S)/(S- Th)= (1 . 2.1)/(2.1-1)=1.9 years] Indicate the type of configuration in position V, III, VII. [east elongation, superior conjunction, east quadrature] What is the period of revolution of Jupiter around the Sun if its conjunction is repeated after 1.1 years. [1/S=1/T h - 1/T , hence T= (Th. S)/(S-Th)= (1 . 1.1)/(1.1-1)=11 years] Indicate the type of configuration in position IV, VI, II. [top connection, west square, bottom connection] Indicate the type of configuration in position VI, V, III. [western quadrature, eastern elongation, superior conjunction] | During the slide show, the groups answer questions, earning points. The price of the question is 2 points. The team that first raised the signal card answers. If the answer is wrong, then the move goes to the next team. The team that has earned the most points receives a 1st class ticket (this gives the right to be the first to advance on a trip and the right to make two mistakes), other teams receive 2nd class tickets (the right to make 1 mistake) and 3rd class tickets (to make a mistake when no answers). | 7 min |
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Stage 3 Defining expectations and concerns Target: Concentration of attention, ensuring responsibility for the result of training, creating a psychologically comfortable environment | Develop the ability to understand the world, navigate in it, realize their role and purpose. Personal - participants not only share their desires, but also reveal the motivational sphere of their personality, their inclinations, interests; identify themselves in relation to the profession | Ticket method | Are you ready for a journey and new knowledge? (The teacher gives each participant a vehicle entry ticket) | The ticket consists of two parts. On one part, students write their expectations from the upcoming trip, and on the other (control zone) - their fears. The teacher tears off the area of control (fear) and takes it for himself, and the part of the ticket on which the expectations are written remains with the student. | 2 minutes |
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Stage 4. Elaboration of the content of the topic. Target: Generalization and systematization of knowledge, development of knowledge, skills and abilities on this topic | Develop the ability to apply previously acquired knowledge. Cognitive UUD: Formulation of hypotheses and assumptions, - ability to apply prior knowledge The ability to choose and argue your position. Communicative UUD: the ability to correctly defend one's point of view, the ability to be tolerant of the opinions of others. Personal UUD: consider the opinion of another person; show patience and goodwill, trust in the interlocutor. Regulatory UUD: evaluate the weight of the reasoning given | Presentation | The teacher addresses the children: In order not to miss anything on the journey, we will record everything we see and hear in the route lists. (In the route lists of the group, students draw up assignments, evaluate their performance, and at the end of the lesson, the success of the group's progress is assessed.). At each station, you complete the proposed tasks and gain points. And so, the journey began and the first station is station "Zamorochki from the barrel". Cinema station Teacher. Let's watch a clip from the movie now. And we will try to understand the topic of our lesson in order to get to the station "Unexplored" Teacher. Primary view of the world around:
Station "Unexplored" ( slides 16-21 ) Attachment 1 | Fill out the itinerary sheets for each group. Route sheet of group No. 1
Carrying out technology: On three tables (tables can be numbered) there are route sheets, the teacher has sheets with tasks for stations, instructions for completing tasks. Answering questions (slides 10-15) Watching a movie Listen to the lecture and join in the conversation | 23 min |
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Stage 5 Emotional discharge (warm-up) Target: Relieve tension and fatigue, relax or restore energy | To develop the ability to correlate general educational knowledge with real cognizable objects, the formation of logical thinking. mastering creative skills productive activity: making assumptions, analyzing them | Method Station "Application" Purpose of the method: decrease in the intensity of work, Carrying out technology: Each group is given a card with a view of the constellations. The team needs to imagine this constellation without saying a word. The other groups need to guess which constellation is shown on the card. | Teacher. Ahead of us is the "Application" station. In the literature we find various descriptions of nature, remember Tyutchev: Not what you think nature: not a cast, not a soulless face it has a soul, it has freedom, it has love, it has a language... What language does physics use to describe the laws of nature? True mathematical language. But you now have to use sign language to show the constellation. You receivedcards with different constellations. Each team needs to introduce this constellation without saying a word. Other groups need to guess what constellation is shown on the card. | Perform tasks | 3 min |
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stage 6 Reflection Purpose: Obtaining an emotional and meaningful assessment of the process and learning outcomes | To develop the ability to conduct analysis, reflection, self-assessment of educational and cognitive activity. | Station "Book of reviews and suggestions" | Teacher. Ahead of us is the “Book of Reviews and Suggestions” station, that is, the final one. Before you is a book of "Reviews and Suggestions" of the company that organized this trip for you. Remember once again the lesson, yourself, your emotions and feelings. What surprised you? What made you think? Or maybe you didn't agree with something? Or maybe you excelled in something? Task: you need to fill out a page of this book. Homework (slide 22) | Each student in this bookremembering once again the lesson, himself, his emotions and feelings, expresses them in any way (poetry, quote or just a smiley) Summing up the results of the competition, the students conduct their own according to the final table on the board. The level of mood at the end of the work is determined. | 3 min |
Attachment 1
Geocentric system of world structure (from Aristotle to Ptolemy).
The first scientifically based theory of the structure of the world was developed Aristotle and published in 355 BC in the book On the Sky. Recognizing the sphericity of the Earth, the Moon and celestial bodies, he refuses the movement of the Earth and puts it in the center, since he believed that the stars would have to describe circles, and not be in place (which was proved only in the 18th century). The system was named geocentric(Gaia - Earth).
With the development of astronomy and the acquisition of more accurate knowledge of the motion of the planets, the system was finalized by Hipparchus and finally kinematically developed by 150 NE by the Alexandrian astronomer Claudius Ptolemy(87-165) in an essay consisting of 13 books “The Great Mathematical Construction of Astronomy” (Almagest). To explain the motion of the planets, using a system of epicycles and deferents.
According to Ptolemy's theory:
The earth is motionless and is at the center of the world;
the planets revolve in strictly circular orbits;
the motion of the planets is uniform.
Heliocentric system of the structure of the world (Copernicus).
The idea to place in the center of the solar system not the Earth but the Sun belongs to Aristarchus of Samos (310-230) who for the first time determined the distance to the Moon, the Sun and their sizes. But the conclusions and evidence that the Sun is larger and the planets are moving around was clearly not enough."He believes that the fixed stars and the Sun do not change their places in space, that the Earth moves in a circle around the Sun, which is in its center," wrote Archimedes. In the work "On the Sizes and Mutual Distances of the Sun and the Moon", Aristarchus of Samos, accepting the hypothesis of the daily rotation of the Earth, knowing the diameter of the Earth (according to Eratosthenes) and considering the Moon 3 times smaller than the Earth, based on his own observations, calculated that the Sun is one, the nearest of the stars - 20 times farther from the Earth than the Moon (actually - 400 times) and more than the Earth in volume by 200-300 times.
Only in the Renaissance, the Polish scientist Nicholas Copernicus (1473-1543) foundedheliocentric system of the structure of the world by 1539 in the book “On the Revolution of the Celestial Spheres” (1543), explaining the daily movement of the luminaries by the rotation of the Earth and the loop-like movement of the planets by their revolution around the Sun, calculating the distances and periods of revolution of the planets. However, he left the sphere of fixed stars, pushing it 1000 times further than the Sun.
Confirmation of the heliocentric system of the world.
AT writingsGalileo Galilei Galilei - Discovered the phase change of Venus, proving its rotation around the Sun. He discovered 4 satellites of Jupiter, proving that not only the Earth can be the center.
In writingsJohannes Kepler reveals the movement of the planets.
In writingsIsaac Newton publishes a law gravity.
In writingsM.V. Lomonosov not only ridicules the ideas of geocentrism in poetry, but also discovered the atmosphere on Venus.
I. Introduction.
II. Picture of the world.
III. The movement of the planets.
IV. The first models of the world.
VI. Ptolemaic system.
VII. World of Copernicus.
VIII. Sun and stars.
IX. Galaxy.
X. Star worlds.
XI. Universe.
XII. Conclusion.
I. Introduction.
The starry sky has occupied the imagination of people at all times. Why do stars light up? How many of them shine at night? Are they far from us? Does the stellar universe have boundaries? Since ancient times, man has thought about these and many other questions, sought to understand and comprehend the structure of the big world in which we live.
The earliest ideas of people about him are preserved in fairy tales and legends. Centuries and millennia passed before the science of the Universe arose and received a deep substantiation and development, revealing to us the remarkable simplicity, the amazing order of the universe. Not without reason, even in ancient greece it was called Cosmos, and this word originally meant "order" and "beauty."
II. Picture of the world.
In the ancient Indian book called "Rig Veda", which means "Book of Hymns", one can find a description - one of the very first in the history of mankind - of the entire Universe as a whole. According to the Rigveda, it is not too complicated. It contains, first of all, the Earth. It appears as a flat, boundless surface - "vast space". This surface is covered from above by the sky. And the sky is a blue dome dotted with stars. Between heaven and earth - "luminous air".
It was very far from science. But something else is important here. Remarkable and grandiose is the daring goal itself - to embrace the whole Universe with thought. From here comes the confidence that the human mind is able to comprehend, understand, unravel its structure, create in its imagination a complete picture of the world.
III. The movement of the planets.
By observing the annual movement of the Sun among the stars, ancient people learned to determine in advance the onset of a particular season. They divided the sky along the ecliptic into 12 constellations, in each of which the Sun is located for about a month. As already noted, these constellations were called zodiacal. All of them, with the exception of one, are named after animals.
Ancient people associated their agricultural work with the morning sunrise of one or another constellation, and this is reflected in the very names of the constellations. So, the appearance of the constellation Aquarius in the sky indicated the expected flood, the appearance of Pisces - the upcoming move of the fish for spawning. With the morning appearance of the constellation Virgo, the harvesting of bread began, which was carried out mainly by women. A month later, the neighboring constellation Libra appeared in the sky, at which time the weighing and counting of the crop was taking place.
As early as 2000 BC. e. ancient observers noticed five special luminaries among the zodiac constellations, which, constantly changing their position in the sky, move from one zodiac constellation to another. Subsequently, Greek astronomers called these luminaries planets, that is, "wandering." These are Mercury, Venus, Mars, Jupiter and Saturn, which have retained the names of the ancient Roman gods in their names to this day. The Moon and the Sun were also counted among the wandering luminaries.
Probably, many centuries passed before the ancient astronomers managed to establish certain patterns in the motion of the planets and, above all, to establish the time intervals after which the position of the planet in the sky in relation to the Sun is repeated. This period of time was later called the synodic period of the planet's revolution. After that, it was possible to take the next step - to build a general model of the world, in which a certain place would be assigned to each of the planets and, using which, it would be possible to predict the position of the planet in advance for several months or years in advance.
According to the nature of their movement in the celestial sphere in relation to the Sun, the planets (in our understanding) are divided into two groups. Mercury and Venus are called internal or inferior, the rest are external or superior.
The angular velocity of the Sun is greater than the velocity of the direct motion of the upper planet. Therefore, the Sun gradually overtakes the planet. As for the inner planets, at the moment when the direction to the planet and to the Sun coincide, the conjunction of the planet with the Sun occurs. After the Sun overtakes the planet, it becomes visible before sunrise, in the second half of the night. The moment when the angle between the direction to the Sun and the direction to the planet is 180 degrees is called the opposition of the planet. At this time, it is in the middle of the arc of its backward movement. The removal of the planet from the Sun by 90 degrees to the east is called the eastern quadrature, and 90 degrees to the west is called the western quadrature. All positions of planets mentioned here concerning the Sun (from the point of view of the terrestrial observer) are called configurations.
During excavations of ancient cities and temples of Babylonia, tens of thousands of clay tablets with astronomical texts were found. Their decoding showed that the ancient Babylonian astronomers closely followed the position of the planets in the sky; they were able to determine their synodic circulation periods and use these data in their calculations.
IV. The first models of the world.
In spite of high level astronomical information of the peoples of the ancient East, their views on the structure of the world were limited to direct visual sensations. Therefore, in Babylon, there were views according to which the Earth looks like a convex island surrounded by an ocean. Inside the Earth, as if there is a "kingdom of the dead." The sky is a solid dome resting on the earth's surface and separating the "lower waters" (the ocean flowing around the earth's island) from the "upper" (rain) waters. On this dome are attached heavenly bodies, gods seem to live above the sky. The sun rises in the morning, coming out of east gate, and enters through the western gate, and at night it moves under the Earth.
According to the ideas of the ancient Egyptians, the Universe looks like a large valley, elongated from north to south, in the center of which is Egypt. The sky was likened to a large iron roof, which is supported on pillars, on which stars are suspended in the form of lamps.
AT Ancient China there was an idea according to which the Earth has the shape of a flat rectangle, above which a round, convex sky is supported on pillars. The enraged dragon seemed to bend the central pillar, as a result of which the Earth leaned towards the east. Therefore, all rivers in China flow to the east. The sky tilted to the west, so all the heavenly bodies move from east to west.
And only in the Greek colonies on the western shores of Asia Minor (Ionia), in southern Italy and in Sicily in the fourth century BC, the rapid development of science, in particular, philosophy, as a doctrine of nature, began. It is here that simple contemplation of natural phenomena and their naive interpretation are replaced by attempts to scientifically explain these phenomena, to unravel their true causes.
One of the outstanding ancient Greek thinkers was Heraclitus of Ephesus (about 530 - 470 BC). It is to him that the words belong: “The world, one of everything, was not created by any of the gods and by any of the people, but was, is and will be an ever-living fire, naturally igniting and naturally extinguishing ...” Then Pythagoras of Samos (c. 580 - 500 BC) expressed the idea that the Earth, like other celestial bodies, has the shape of a ball. The Universe was presented to Pythagoras in the form of concentric transparent crystal spheres embedded in each other, to which the planets seemed to be attached. In this model, the Earth was placed in the center of the world, the spheres of the Moon, Mercury, Venus, Sun, Mars, Jupiter and Saturn revolved around it. Furthest away was the sphere of the fixed stars.
The first theory of the structure of the world, explaining the direct and backward movement of the planets, was created by the Greek philosopher Eudoxus of Cnidus (about 408 - 355 BC). He suggested that each planet has not one but several spheres attached to each other. One of them makes one revolution per day around the axis of the celestial sphere in the direction from east to west. The time of revolution of the other (in the opposite direction) was assumed to be equal to the period of revolution of the planet. This explained the motion of the planet along the ecliptic. It was assumed that the axis of the second sphere is inclined to the axis of the first at a certain angle. The combination of two more spheres with these spheres made it possible to explain the backward movement in relation to the ecliptic. All features of the movement of the Sun and Moon were explained using three spheres. Eudoxus placed the stars on one sphere containing all the others. Thus, all the visible movement of the celestial bodies Eudoxus reduced to the rotation of 27 spheres.
It is appropriate to recall that the idea of a uniform, circular, perfectly regular movement of celestial bodies was expressed by the philosopher Plato. He also suggested that the Earth is in the center of the world, that the Moon, the Sun revolve around it, then morning Star Venus, the star of Hermes, the stars of Ares, Zeus and Kronos. Plato first found the names of the planets by the name of the gods, which completely coincide with the Babylonian ones. Plato first formulated the problem for mathematicians: to find with the help of what uniform and regular circular motions one can "save the phenomena represented by the planets." In other words, Plato set the task of constructing a geometric model of the world, in the center of which, of course, the Earth should have been.
Plato's disciple Aristotle (384 - 322 BC) took up the improvement of the system of the world of Eudoxus. Since the views of this outstanding philosopher - encyclopedist reigned supreme in physics and astronomy for almost two thousand years, we will dwell on them in more detail.
Aristotle, following the philosopher Empedocles (about 490 - 430 BC), suggested the existence of four "elements": earth, water, air and fire, from the mixing of which all the bodies found on Earth allegedly originated. According to Aristotle, the elements water and earth naturally tend to move towards the center of the world ("down"), while fire and air move "up" to the periphery and the faster, the closer they are to their "natural" place. Therefore, in the center of the world is the Earth, above it are water, air and fire. According to Aristotle, the Universe is limited in space, although its movement is eternal, has neither end nor beginning. This is possible just because, in addition to the four elements mentioned, there is also a fifth, indestructible matter, which Aristotle called ether. It is as if all celestial bodies consist of ether, for which perpetual circular motion is a natural state. The "zone of ether" begins near the moon and extends upward, while below the moon is the world of the four elements.
Here is how Aristotle himself describes his understanding of the universe:
“The sun and planets revolve around the Earth, which is motionless in the center of the world. Our fire, in relation to its color, has no resemblance to the light of the sun, dazzling whiteness. The sun is not made of fire; it is a huge accumulation of ether; The heat of the Sun is caused by its action on the ether during its revolution around the Earth. Comets are transient phenomena that are quickly born in the atmosphere and just as quickly disappear. The Milky Way is nothing but vapors ignited by the rapid rotation of the stars around the Earth... The movements of celestial bodies, generally speaking, occur much more regularly than the movements noticed on Earth; for, since celestial bodies are more perfect than any other bodies, the most regular movement, and at the same time the simplest, befits them, and such movement can only be circular, because in this case the movement is at the same time uniform. The heavenly bodies move freely like the gods, to whom they are closer than to the inhabitants of the Earth; therefore, the luminaries do not need rest during their movement, and the cause of their movement is contained in themselves. Therefore, the higher regions of the sky, more perfect, containing fixed stars, have the most perfect movement - always to the right. As for the part of the sky closest to the Earth, and therefore less perfect, this part serves as the seat of much less perfect luminaries, such as the planets. These latter move not only to the right, but also to the left, and, moreover, in orbits inclined to the orbits of the fixed stars. All heavy bodies tend to the center of the Earth, and since every body tends to the center of the Universe, therefore the Earth must also be motionless in this center.
When building his system of the world, Aristotle used the ideas of Eudoxus about the concentric spheres on which the planets are located and which revolve around the Earth. According to Aristotle, the root cause of this movement is the "first engine" - a special rotating sphere located behind the sphere of "fixed stars", which sets everything else in motion. According to this model, only one sphere in each of the planets rotates from east to west, the other three - in the opposite direction. Aristotle believed that the action of these three spheres should be compensated by an additional three inner spheres belonging to the same planet. It is in this case that only a daily rotation acts on each subsequent (towards the Earth) planet. Thus, in the system of the world of Aristotle, the movement of celestial bodies was described with the help of 55 hard crystal spherical shells.
Later, in this system of the world, eight concentric layers (heavens) were distinguished, which transmitted their movement to each other. In each such layer, there were seven spheres moving this planet.
At the time of Aristotle, other views on the structure of the world were also expressed, in particular, that it is not the Sun that revolves around the Earth, but the Earth, together with other planets, revolves around the Sun. Against this, Aristotle put forward a serious argument: if the Earth moved in space, then this movement would lead to a regular apparent movement of the stars in the sky. As we know, this effect (annual parallactic shift of stars) was discovered only in the middle of the 19th century, 2150 years after Aristotle...
In his declining years, Aristotle was accused of godlessness and fled from Athens. In fact in his understanding of the world he vacillated between materialism and idealism. His idealistic views and, in particular, the idea of the Earth as the center of the universe was adapted to protect religion. That is why, in the middle of the second millennium of our era, the struggle against the views of Aristotle became necessary condition development of science...
V. The first heliocentric system.
Aristotle's contemporaries already knew that the planet Mars at opposition, as well as Venus during the backward movement, is much brighter than at other times. According to the theory of spheres, they should always remain at the same distance from the Earth. That is why then there were other ideas about the structure of the world.
So, Heraclitus of Pontus (388 - 315 BC) assumed that the Earth moves "... rotationally, around its axis, like a wheel, from west to east around its own center." He also expressed the idea that the orbits of Venus and Mercury are circles, in the center of which is the Sun. Together with the Sun, these planets seem to revolve around the Earth.
Even more bold views were held by Aristarchus of Samos (about 310 - 230 BC). The outstanding ancient Greek scholar Archimedes (circa 287 - 212 BC), in his work "Psammit" ("Calculation of grains of sand"), referring to Gelon of Syracuse, wrote about the views of Aristarchus as follows:
“You know that, according to some astronomers, the world has the shape of a sphere, the center of which coincides with the center of the Earth, and the radius equal to length straight line connecting the centers of the Earth and the Sun. But Aristarchus of Samos, in his "Proposals" written against astronomers, rejecting this idea, comes to the conclusion that the world is much larger than just indicated. He believes that the fixed stars and the Sun do not change their place in space, that the Earth moves in a circle around the Sun, which is at its center, and that the center of the sphere of fixed stars coincides with the center of the Sun, and the size of this sphere is such that the circle described by his assumption, the Earth, is to the distance of the fixed stars in the same relation as the center of the ball is to its surface.
VI. Ptolemy system.
The formation of astronomy as an exact science began thanks to the work of the outstanding Greek scientist Hipparchus. He was the first to start systematic astronomical observations and their comprehensive mathematical analysis, laid the foundations of spherical astronomy and trigonometry, developed the theory of the motion of the Sun and Moon and, on its basis, methods for predicting eclipses.
Hipparchus discovered that the apparent movement of the Sun and Moon in the sky is uneven. Therefore, he took the point of view that these luminaries move uniformly in circular orbits, but the center of the circle is displaced with respect to the center of the Earth. Such orbits were called eccentres. Hipparchus compiled tables by which it was possible to determine the position of the Sun and Moon in the sky on any day of the year. As for the planets, according to Ptolemy, he “did not make other attempts to explain the motion of the planets, but was content with putting in order the observations made before him, adding to them a much larger number of his own. He limited himself to pointing out to his contemporaries the unsatisfactoriness of all the hypotheses by which some astronomers thought to explain the movement of the heavenly bodies.
Thanks to the work of Hipparchus, astronomers abandoned the imaginary crystal spheres proposed by Eudoxus and moved on to more complex constructions using epicycles and deferents, proposed even before Hipparchus by Apollo of Perga. The classical form of the theory of epicyclic motions was given by Claudius Ptolemy.
The main work of Ptolemy "Mathematical Syntax in 13 Books" or, as the Arabs later called it, "Almagest" ("The Greatest") became known in medieval Europe only in the 12th century. In 1515 it was printed in Latin, translated from Arabic, and in 1528, translated from Greek. The Almagest was published three times in Greek, and in 1912 it was published in German.
"Almagest" is a real encyclopedia of ancient astronomy. In this book, Ptolemy did what none of his predecessors could do. He developed a method by which it was possible to calculate the position of a particular planet at any predetermined point in time. This was not easy for him, and in one place he remarked:
“It seems easier to move the planets themselves than to comprehend their complex movement...”
By "setting" the Earth at the center of the world, Ptolemy presented the apparent complex and uneven motion of each planet as the sum of several simple, uniform circular motions.
According to Ptolemy, each planet moves uniformly in a small circle - an epicycle. The center of the epicycle, in turn, slides uniformly around the circumference of a large circle called the deferent. For a better agreement between the theory and observational data, it was necessary to assume that the center of the deferent is displaced with respect to the center of the Earth. But that wasn't enough. Ptolemy was forced to assume that the movement of the center of the epicycle along the deferent is uniform (i.e., its angular velocity of movement is constant), if we consider this movement not from the center of the deferent and not from the center of the Earth, but from some “leveling point”, later called the equant .
Combining observations with calculations, Ptolemy obtained by successive approximations that the ratios of epicycle radii to deferent radii for Mercury, Venus, Mars, Jupiter, and Saturn are 0.376, 0.720, 0.658, 0.192, and 0.103, respectively. It is curious that in order to predict the position of the planet in the sky, it was not necessary to know the distances to the planet, but only the mentioned ratio of the radii of epicycles and deferents.
When constructing his geometric model of the world, Ptolemy took into account the fact that in the process of their movement the planets deviate somewhat from the ecliptic. Therefore, for Mars, Jupiter and Saturn, he "tilted" the planes of the deferents to the ecliptic and the planes of the epicycles to the planes of the deferents. For Mercury and Venus, he introduced up and down oscillations using small vertical circles. In general, to explain all the features noticed at that time in the motion of the planets, Ptolemy introduced 40 epicycles. The system of the world of Ptolemy, in the center of which is the Earth, is called geocentric.
In addition to the ratio of the radii of epicycles and deferents, in order to compare the theory with observations, it was necessary to set the periods of revolution along these circles. According to Ptolemy, all the upper planets make a complete revolution around the circumference of the epicycles in the same period of time as the Sun does along the ecliptic, that is, in a year. Therefore, the radii of the epicycles of these planets, directed towards the planets, are always parallel to the direction from the Earth to the Sun. In the lower planets - Mercury and Venus - the period of revolution along the epicycle is equal to the period of time, and during which the planet returns to its starting point in the sky. For periods of revolutions of the center of the epicycle along the circumference of the deferent, the picture is reversed. For Mercury and Venus, they are equal to a year, so the centers of their epicycles always lie on a straight line connecting the Sun and Earth. For outer planets they are determined by the time during which the planet, having described a complete circle in the sky, returns to the same stars.
Following Aristotle, Ptolemy tried to refute the idea of the possible motion of the Earth. He wrote:
“There are people who claim that nothing prevents us from assuming that the sky is motionless, and the Earth rotates about its axis from west to east, and that it makes such a revolution every day. True, speaking of the luminaries, nothing prevents, for greater simplicity, from assuming this, if only visible movements are taken into account. But these people do not realize to what extent such an opinion is ridiculous, if you look closely at everything that happens around us and in the air. If we agree with them - which is not really the case - that the lightest bodies do not move at all, or move in the same way as heavy bodies, while, obviously, air bodies move with greater speed than earthly bodies; if we agreed with them that the densest and heaviest objects have their own movement, fast and constant, while in fact they move with difficulty from the shocks imparted to them, all the same, these people would have to admit that the Earth is due to of its rotation would have a movement much faster than all those that occur around it, because it would make such a large circle in such a small period of time. Thus, the bodies that would support the Earth would always seem to move in the opposite direction from it, and no cloud, nothing flying or thrown would ever seem to be heading towards the east, for the Earth would outstrip any movement in this direction.
From a modern point of view, we can say that Ptolemy overestimated the role of centrifugal force too much. He also adhered to Aristotle's erroneous assertion that in a gravitational field bodies fall with velocities proportional to their masses...
On the whole, as A. Pannekoek noted, Ptolemy's “Mathematical Work” “was a carnival procession of geometry, a celebration of the deepest creation of the human mind in the representation of the Universe .. Ptolemy's work appears before us as great monument ancient sciences...
After the high flowering of ancient culture on the European continent, a period of stagnation and regression began. This gloomy period of time lasting more than a thousand years has been called the Middle Ages. It was preceded by the transformation of Christianity into the dominant religion, in which there was no place for the highly developed science of ancient antiquity. At this time, there was a return to the most primitive ideas about a flat Earth.
And only starting from the 11th century, under the influence of the growth of trade relations, with the strengthening of a new class in the cities - the bourgeoisie, the spiritual life in Europe began to awaken. In the middle of the XIII century. the philosophy of Aristotle was adapted to Christian theology, the decisions of church councils that forbade the natural philosophical ideas of the great ancient Greek philosopher were canceled. Aristotle's views on the structure of the world soon became integral elements of the Christian faith. Now it was no longer possible to doubt that the Earth has the shape of a ball, installed in the center of the world, and that all the heavenly bodies revolve around it. The Ptolemaic system became, as it were, an addition to the Aristotle system, which helps to carry out specific calculations of the positions of the planets.
Ptolemy determined the main parameters of his model of the world in the highest degree skillfully and with high accuracy. Over time, however, astronomers began to become convinced that there were discrepancies between the true position of the planet in the sky and the calculated one. So, at the beginning of the 12th century, the planet Mars was two degrees away from the place where it should have been according to the tables of Ptolemy.
To explain all the features of the motion of the planets in the sky, it was necessary to introduce for each of them up to ten or more epicycles with ever-decreasing radii so that the center of the smaller epicycle revolves around the circle of the larger one. By the 16th century, the movement of the Sun, Moon and five planets was explained using over 80 circles! And yet, observations separated by large intervals of time were difficult to “fit” into this scheme. It was necessary to introduce new epicycles, slightly change their radii, and shift the centers of the deferents with respect to the center of the Earth. In the end, the geocentric system of Ptolemy, overloaded with epicycles and equants, collapsed from its own weight...
VII. World of Copernicus.
The book of Copernicus, published in the year of his death, in 1543, had a modest title: "On the rotation of the celestial spheres." But it was a complete overthrow of Aristotle's views on the world. The complex colossus of transparent crystal hollow spheres is a thing of the past. Since that time, a new era has begun in our understanding of the Universe. It continues to this day.
Thanks to Copernicus, we have learned that the Sun occupies its proper position in the center of the planetary system. The earth is not the center of the world, but one of the ordinary planets revolving around the sun. So everything fell into place. The structure of the solar system was finally unraveled.
Further discoveries of astronomers added to the family of large planets. There are nine of them: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. In this order, they occupy their orbits around the Sun. Many small bodies of the solar system - asteroids and comets - have been discovered. But this did not change the new Copernican picture of the world. On the contrary, all these discoveries only confirm and refine it.
Now we understand that we live on a small planet that looks like a ball. The earth revolves around the sun in an orbit that is not too different from a circle. The radius of this circle is close to 150 million kilometers.
The distance from the Sun to Saturn - the farthest planet known at the time of Copernicus - is approximately ten times the radius of the earth's orbit. This distance was quite correctly determined by Copernicus. The size of the solar system - the distance from the Sun to the orbit of the ninth planet, Pluto, is still almost four times greater and is approximately 6 billion kilometers.
This is the picture of the universe in our immediate environment. This is the world according to Copernicus.
But the solar system is not the entire universe. We can say that this is just our little world. What about distant stars? About them Copernicus did not dare to express any definite opinion. He simply left them in their original place, not the distant sphere where Aristotle had them, and only said, and quite rightly, that the distance to the stars is many times greater than the size of the planetary orbits. Like ancient scientists, he represented the Universe as a closed space, limited by this sphere.
VIII. Sun and stars.
On a clear moonless night, when nothing interferes with observation, a person with sharp eyesight will see no more than two to three thousand twinkling dots in the sky. The list, compiled in the 2nd century BC by the famous ancient Greek astronomer Hipparchus and later supplemented by Ptolemy, contains 1022 stars. Hevelius, the last astronomer who made such calculations without the help of a telescope, brought their number to 1533.
But already in antiquity, the existence of a large number stars invisible to the eye. Democritus, the great scientist of antiquity, said that the whitish strip that stretches across the whole sky, which we call milky way, is in reality a combination of the light of a multitude of individually invisible stars. Structural controversy Milky Way continued for centuries. The decision - in favor of Democritus' conjecture - came in 1610, when Galileo reported the first discoveries made in the sky with a telescope. He wrote with understandable excitement and pride that now it was possible to "make available to the eye stars that have never been visible before and whose number is at least ten times greater than the number of stars known from ancient times."
But this great discovery still left the world of stars mysterious. Are all of them, visible and invisible, really concentrated in a thin spherical layer around the Sun?
Even before Galileo's discovery, a completely unexpected idea, remarkably bold for those times, was expressed. It belongs to Giordano Bruno, whose tragic fate is known to all. Bruno put forward the idea that our Sun is one of the stars of the universe. Only one of the great many, and not the center of the entire universe. But then any other star could also have its own planetary system.
If Copernicus indicated the place of the Earth by no means in the center of the world, then Bruno and the Sun deprived of this privilege.
Bruno's idea gave rise to many striking consequences. From it followed an estimate of the distances to the stars. Indeed, the Sun is a star like the others, but only the closest to us. That's why it's so big and bright. And how far should the luminary be moved so that it looks like, for example, Sirius? The answer to this question was given by the Dutch astronomer Huygens (1629 - 1695). He compared the brightness of these two celestial bodies, and this is what turned out: Sirius is hundreds of times farther from us than the Sun.
To better imagine how great the distance to a star is, let's say that a beam of light flying 300,000 kilometers in one second takes several years to travel from Sirius to us. Astronomers speak in this case of a distance of several light years. According to modern updated data, the distance to Sirius is 8.7 light years. And the distance from us to the sun is only 8 light minutes.
Of course, different stars differ from each other (this is taken into account in modern assessment distance to Sirius). Therefore, determining the distances to them even now often remains a very difficult, and sometimes simply unsolvable task for astronomers, although since the time of Huygens many new methods have been invented for this.
Bruno's remarkable idea and Huygens' calculation based on it became a decisive step towards mastering the secrets of the Universe. Thanks to this, the boundaries of our knowledge about the world have greatly expanded, they have gone beyond the solar system and reached the stars.
IX. Galaxy.
Since the 17th century, the most important goal of astronomers has been the study of the Milky Way - this giant collection of stars that Galileo saw with his telescope. The efforts of many generations of astronomers - observers were aimed at finding out what is the total number of stars in the Milky Way, determining its actual shape and boundaries, and estimating its size. Only in the 19th century was it possible to understand that this is a single system that contains all the visible stars. On an equal footing with everyone, this system includes our Sun, and with it the Earth and planets. Moreover, they are located far from its center, but on its outskirts.
It took many more decades of careful observations and deep reflections before the structure of the Galaxy was revealed to astronomers in its entirety. So they began to call the star system, which we see - of course, from the inside - as a strip of the Milky Way. (The word "galaxy" is derived from the modern Greek "galaktikos", which means "milky".)
It turned out that the Galaxy has a fairly regular structure and shape, despite the apparent raggedness of the Milky Way, the disorder with which, as it seems to us, the stars are scattered across the sky. It consists of a disk, a halo and a crown. The disk is like two plates folded by the edges. It is formed by stars that, inside this volume, move in almost circular orbits around the center of the Galaxy.
The diameter of the disk is measured - it is approximately 100 thousand light years. This means that it will take one hundred thousand years for light to cross the disk from end to end in diameter. How big is the galaxy! And the number of stars in the disk is about one hundred billion.
The halo contains a comparable number of stars (the word "halo" means "round".). They fill a slightly flattened spherical volume and move not in circular, but in highly elongated orbits. The planes of these orbits pass through the center of the Galaxy. In different directions they are distributed more or less evenly.
The disk and the halo surrounding it are immersed in the corona. If the radii of the disk and halo are comparable in size, then the radius of the corona is five, and maybe ten times greater. Why maybe"? Yes, because it is invisible - no light comes from it. How did astronomers find out about it then?
All bodies in nature create gravity and experience its action. This is evidenced by the Law of universal gravitation discovered by Newton. So they learned about the crown not by the light, but by the gravity it creates. It affects the visible stars, emitting light gas clouds. Observing the movement of these bodies, astronomers noticed that in addition to the disk and the halo, something else acts on them.
A detailed study of this “something” made it possible, in the end, to discover the crown, which creates additional gravity. It turned out to be very massive - several times the mass of all the stars included in the disk and halo.
Such is the information obtained by the Soviet astronomer J. Einasto and his collaborators at the Tartu Observatory.
Of course, studying the invisible corona is very difficult. Because of this, estimates of its size and mass are not too accurate yet. But its main mystery lies elsewhere: we do not know what it consists of. We do not know if there are stars in it, even if they are some unusual ones that do not emit light at all.
Now many people assume that its mass does not consist of stars at all, but of the smallest elementary particles - neutrinos. These particles have been known to physicists for a long time, but in themselves they are also in to a large extent remain mysterious. It is not known about them, one might say, the most important thing: do they have a rest mass, that is, such a mass that a particle has in a state when it does not move, but stands still. Majority elementary particles have such a mass.
These are, for example, electrons, protons, neutrons, of which all atoms are composed. But a photon, a quantum of light, does not have it. Photons exist only in motion. Neutrinos could serve as material for the corona, but only if they have a rest mass.
It is easy to imagine with what impatience astronomers await news from physics laboratories, where special experiments are now being set up to find out whether the neutrino has a rest mass or not. Perhaps it is physicists who will solve the mystery of the invisible crown.
X. Star worlds.
By the beginning of our century, the boundaries of the explored Universe had expanded so much that they included the Galaxy. Many, if not all, thought then that this huge star system is the entire Universe as a whole.
But in the 1920s, new large telescopes were built, and completely unexpected horizons opened up before astronomers. It turned out that the world does not end outside the Galaxy. Billions of star systems, galaxies similar to ours and different from it, are scattered here and there throughout the expanses of the Universe.
Photographs of galaxies taken with the most large telescopes, amaze with the beauty and variety of forms: these are powerful whirlwinds of stellar clouds, and regular balls, while other star systems do not show any definite forms at all, they are ragged and shapeless. All these types of galaxies - spiral, elliptical, irregular - named after their appearance in photographs, were discovered by the American astronomer E. Hubble in the 20-30s of our century.
Recent studies have shown that many large spiral galaxies have - like our Galaxy - extended and massive invisible coronas. This is very important: after all, if so, then, then, almost the entire mass of the Universe (or, in any case, its overwhelming part) is a mysterious, invisible, but gravitating "hidden" mass.
Many, and perhaps almost all, galaxies are collected in various collectives, which are called groups, clusters and superclusters, depending on how many there are. A group can include only three or four galaxies, and a supercluster can contain up to a thousand or even several tens of thousands. Our Galaxy, the Andromeda Nebula and more than a thousand of the same objects are included in the so-called Local Supercluster. It does not have a clearly defined shape.
Approximately the same structure is used for other superclusters that lie far from us, but are quite clearly distinguishable in modern large telescopes.
Until recently, astronomers believed that these objects are the largest formations in the universe and that there are no other large systems. But it turned out that this is not so.
A few years ago, astronomers made an amazing map of the universe. On it, each galaxy is represented by just a dot. At first glance, they are randomly scattered on the map. If you look closely, you can find groups, clusters and superclusters that look like chains of dots here. But what is most striking of all, the map reveals that some of these chains connect and intersect, forming some kind of mesh or honeycomb pattern, reminiscent of lace or maybe a honeycomb with cell sizes of 100-300 million light-years.
Whether such "grids" cover the entire universe remains to be seen. But several individual cells outlined by superclusters have been studied in detail. There are almost no galaxies inside them, they are all collected in "walls".
Cell is the tentative, working name for the largest formation in the universe. There are no larger systems in nature. This is shown by the map of the universe. Astronomy has finally reached the completion of one of its most ambitious tasks: the entire sequence, or, as they say, the hierarchy, of astronomical systems is now completely known. But still...
XI. Universe.
More than anything else, the Universe itself, embracing and including all the planets, stars, galaxies, clusters, superclusters and cells. The range of modern telescopes reaches several billion light years.
Planets, stars, galaxies amaze us amazing variety their properties, the complexity of the structure. And how does the whole Universe, the Universe as a whole, work?
Its main property is uniformity. This can be said even more precisely. Let us imagine that we have mentally singled out a very large cubic volume in the Universe, with an edge of 500 million light years. Let's calculate how many galaxies are in it. Let's make the same calculations for other, but equally gigantic volumes located in different parts of the Universe. If all this is done and the results are compared, it turns out that each of them, no matter where they are taken, contains the same number of galaxies. The same will happen when counting clusters or even cells.
The universe appears to us everywhere the same - "continuous" and homogeneous. You can't think of a simpler device. I must say that people have long suspected this. Pointing out, for reasons of maximum simplicity of the device, the general homogeneity of the world, the remarkable thinker Pascal (1623-1662) said that the world is a circle, the center of which is everywhere, and the circumference is nowhere. Thus, with the help of a visual geometric image, he asserted the homogeneity of the world.
In a homogeneous world, all "places" are equal and any of them can claim to be the center of the world. And if so, it means that no center of the world exists at all.
The Universe also has one more important property, but it was never even guessed at. The universe is in motion - it is expanding. The distance between clusters and superclusters is constantly increasing. They seem to run away from each other. And the mesh network is stretched.
A real revolution in the science of the Universe was made in 1922-1924 by the work of the Leningrad mathematician and physicist A. Fridman. Based on the general theory of relativity just created by A. Einstein, he mathematically proved that the world is not something frozen and unchanging. As a whole, he lives his dynamic life, changes in time, expanding or contracting according to strictly defined laws.
Friedman discovered the mobility of the stellar universe. This was a theoretical prediction, and the choice between expansion and contraction must be made based on astronomical observations. Such observations were made in 1928-1929 by Hubble, the explorer of galaxies already known to us.
He discovered that distant galaxies and their entire collectives are moving, moving away from us in all directions. But this is how the general expansion of the universe should look, in accordance with Friedman's predictions.
Of course, this does not mean that galaxies are running away from us. Otherwise, we would have returned to the old views, to the pre-Copernican picture of the world with the Earth in the center. In fact, the general expansion of the Universe occurs in such a way that they all move away from each other, and from any place the picture of this recession looks like we see it from our planet.
If the universe is expanding, then the clusters were closer together in the distant past. Moreover, it follows from Friedman's theory that fifteen to twenty billion years ago there were no stars or galaxies, and all matter was mixed and compressed to a colossal density. This substance was then unthinkably hot. From such a special state, the general expansion began, which eventually led to the formation of the Universe as we see and know it now.
General ideas about the structure of the universe have evolved throughout the history of astronomy. However, only in our century could appear modern science about the structure and evolution of the universe - cosmology.
XII. Conclusion.
We know the structure of the universe in a vast volume of space, which light takes billions of years to cross. But the inquisitive thought of man strives to penetrate further. What lies beyond the observable region of the world? Is the universe infinite in volume? And its expansion - why did it start and will it always continue in the future? And what is the origin of the "hidden" mass? And, finally, how did intelligent life originate in the Universe?
Does it exist anywhere else besides our planet? There are no definitive and complete answers to these questions yet.
The universe is inexhaustible. The thirst for knowledge is also tireless, forcing people to ask more and more new questions about the world and persistently seek answers to them.
BIBLIOGRAPHY.
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2) I. A. Klimishin. Astronomy of our days. - M.: "Science"., 1976. - 453 p.
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Content. I. Introduction. II. Picture of the world. III. The movement of the planets. IV. The first models of the world. V. The first heliocentric system. VI. Ptolemaic system. VII. World of Copernicus. VIII. Sun and stars.