During Columbus's lifetime, people believed that the Earth was flat. They believed that in the Atlantic Ocean there lived monsters of enormous size that could swallow their ships, and that there were terrible waterfalls on which their ships would perish. Columbus had to fight these strange ideas to convince people to sail with him. He was sure that the Earth was round.
- Emma Miler Bolenius, American textbook author, 1919
One of the longest-lived myths that children in the United States grow up believing is that Columbus was the only person of his time who believed that the Earth was round. The rest believed that it was flat. “How brave the sailors of 1492 must have been,” you think, “to go to the edge of the world and not be afraid to fall off it!”
Indeed, there are many ancient references to a disk-shaped Earth. And if, of all the celestial bodies, only the Sun and the Moon were known to you, you could independently come to the same conclusion.
If you go outside at sunset, a day or two after the new moon, you will see something like the following.
A thin crescent of the Moon, the illuminated part of which coincides with the part of the sphere that could be illuminated by the Sun.
If you had a scientific mind and curiosity, you could go outside in the following days and observe what happens next.
Not only does the Moon change position by about 12 degrees each night, moving further from the Sun, but it is also becoming increasingly illuminated! You might (correctly) conclude that the Moon revolves around the Earth, and that the changing phases are due to the light of the Sun illuminating different parts of the round Moon.
Ancient and modern views The phases of the moon coincide in this.
But about twice a year, something happens during the full moon that allows us to determine the shape of the Earth: a lunar eclipse! During full moon The Earth passes between the Sun and the Moon, and the shadow of the Earth becomes visible on the surface of the Moon.
And if you look at this shadow, it becomes clear that it is curved and has the shape of a disk!
True, it cannot be deduced from this whether the Earth is a flat disk or a round sphere. One can only see that the Earth's shadow is round.
But, despite the popular myth, the question of the shape of the Earth was not resolved in the 15th or 16th centuries(when Magellan committed trip around the world), but about 2000 years ago, in ancient world. And what’s most amazing is that all it took was the Sun.
If you track the Sun's path across the daytime sky while living in the northern hemisphere, you will notice that it rises in the eastern sky, peaks in the south, and then declines and sets in the west. And so on any day of the year.
But the paths throughout the ode are slightly different. The sun rises much higher and shines for more hours in the summer, while in winter it rises lower and shines less. To illustrate, note the photo of the solar path taken during the winter solstice in Alaska.
If you plot the path of the Sun across the daytime sky, you will find that the lowest path, and the shortest in time, occurs at the winter solstice - usually December 21 - and the highest path (and longest) occurs during summer solstice, usually June 21st.
If you made a camera that could photograph the Sun's path across the sky throughout the year, you would end up with a series of arcs, the tallest and longest of which was made on the summer solstice, and the lowest and shortest on the winter solstice.
In the ancient world, the greatest scholars of Egypt, Greece and the entire Mediterranean worked in the Library of Alexandria. One of them was the ancient Greek astronomer Eratosthenes.
While living in Alexandria, Eratosthenes received amazing letters from the city of Siena in Egypt. It said, in particular, that on the day of the summer solstice:
The shadow of a person looking into a deep well will block the reflection of the Sun at noon.
In other words, the Sun will be directly overhead, without deviating a single degree to the south, north, east or west. And if you had a completely vertical object, it wouldn't cast a shadow.
But Eratosthenes knew that this was not the case in Alexandria. The sun comes closer to its highest point at noon during the summer solstice in Alexandria than on other days, but vertical objects there also cast shadows.
And like any good scientist, Eratosthenes set up an experiment. By measuring the length of the shadow cast by a vertical stick on the summer solstice, he was able to measure the angle between the Sun and the vertical direction at Alexandria.
He got one fiftieth of a circle, or 7.2 degrees. But at the same time, in Siena the angle between the Sun and the vertical stick was zero degrees! Why could this happen? Perhaps, thanks to a brilliant insight, Eratosthenes realized that Sun rays may be parallel, but the Earth may be curved!
If he could then find out the distance from Alexandria to Siena, knowing the difference in angles, he could calculate the circumference of the Earth! If Eratosthenes had been a graduate student's supervisor, he would have sent him on his way to measure distances!
But instead he had to rely on the then known distance between the two cities. And the most accurate measurement method back then was...
Traveling on a camel. One can understand the criticism of such precision. And yet, he considered the distance between Siena and Alexandria to be 5000 stadia. The only question is the length of the stage. The answer depends on whether Eratosthenes, a Greek who lived in Egypt, used Attic or Egyptian stages, which historians still debate. The Attic stage was used more often and is 185 meters long. Using this value, the circumference of the Earth can be obtained as 46,620 km, which is 16% larger than the actual value.
But the Egyptian stade is only 157.5 meters, and perhaps this is what Eratosthenes had in mind. In this case, the result is 39,375, which is different from modern meaning at 40,041 km by only 2%!
Regardless of the numbers, Eratosthenes became the world's first geographer, invented the concepts of latitude and longitude that are still used today, and built the first models and maps based on a spherical Earth.
And although much has been lost over the millennia that have passed since then, the idea of a spherical Earth and knowledge of its approximate circumference have not disappeared. Today, anyone can repeat the same experiment with two places at the same longitude and, by measuring the lengths of the shadows, get the circumference of the Earth! Not bad, considering that the first direct photographic evidence of the curvature of the Earth would not be obtained until 1946!
Knowing the shape and size of the Earth since 240 BC, we have been able to figure out many wonderful things, including the size and distance of the Moon! Therefore, let us pay tribute to Eratosthenes for the discovery that the Earth is round and for the first exact count her size!
If there's one thing Columbus should be remembered for regarding the size and shape of the Earth, it's that he used values for its circumference that were too small! His estimates of the distances by which he convinced that a ship could sail from Europe directly to India (if there were no Americas) were incredibly small! And if America had not existed, he and his team would have died of hunger before reaching Asia!
At the end of September, the domestic program “The Most Shocking Hypotheses” aired on REN-TV, which excited the public.
For a whole 45 minutes, in all seriousness, specialists, experts and even a whole former NASA employee prove to the viewer that planet Earth actually flat.
If you don't believe me, here's the show, enjoy:
Ask any schoolchild what shape our planet is. Average answer: spherical. And why all?
- Yes, they teach us that at school.
Stop fooling us! WITH light hand REN-TV everything more people start to believe in a flat earth.
Earth figure
Any child will say that the Earth is round. Almost. Officially, our planet has the shape of a geoid, that is, a ball slightly flattened at the poles.
Adherents of revolutionary theory deny this. Among them it is believed that we live on a flat disk with curved edges, which is covered with a dome on top. The North Pole is located in the center of the disk, and the South Pole does not exist as such. This is a kind of ice wall that protects us.
Doesn't remind you of anything?
In Game of Thrones, for example, the world is also flat. And the border is a huge wall, beyond which wildlings live, and white walkers rule the roost. Who knows, maybe this is not fiction, but real story.
Why don't we know anything
There is an opinion that NASA is constantly misleading us ordinary people.
In the program “The Most Shocking Hypotheses,” ex-NASA employee Matthew Boylan himself claims that the Earth is flat and its real appearance can be seen on the UN flag.
For several years he painted a blue round planet and passed it off as reality. So, in his opinion, the department exists only to promote the theory of the sphericity of the planet.
The only way to check is to get a job in the department.
Curvature
Scientists came up with the curvature parameter. In reality, neither architects, nor militaries, nor planners ignore the fact that the planet is spherical. When calculating, it is assumed that the Earth is stationary and flat. And everything works out: the shells fall where they should, the buildings are not destroyed. If we live on a geoid, then why doesn’t this fact count?
In practice I can give an example: The city of Chicago is visible across the bay from a distance of 140 km, which contradicts science.
If the Earth were a ball, the city would sink about 1.5 km down relative to the observer.
Check it out for yourself
In May 2017, American Darryl Marble was able to simply and easily prove the flat-earther hypothesis while flying on an airplane.
If the Earth is spherical, then the ship should fly along a curved trajectory; thus, at certain intervals, the pilot needs to lower the nose of the aircraft so that it does not fly into space or into the upper atmosphere.
Darryl took it with him on the flight building level. However, throughout the 23 minutes or 326 km of travel, the plane never lowered its nose. Means, it flies exactly in a horizontal straight line, and the Earth is flat.
Try it too. Launch the construction level on your phone during your next flight.
What about space flights?
Everything is set up! The filming was edited, fortunately technology allows it. In fact, humanity has never left the near-Earth dome.
Pictures are taken using a Fisheye lens. So any straight object in the photo will become spherical. The videos are generally all edited using chromakey technology. Attentive observers notice air bubbles, studio lighting, and reflections in spacesuits.
Is everything we know a myth?
You will say that ships sooner or later disappear on the horizon. Yes, but this does not happen because the surface is curved. We simply cease to clearly distinguish objects due to the density of the atmosphere.
They say gravity doesn't exist either. Our disk simply flies upward with an acceleration of 9.8 m/s 2 and thus keeps us on the surface. True, it is not yet entirely clear why birds remain in the air, for example.
Admit it, you didn’t hold a “candle” in space. There is no 100% evidence that the Earth is spherical. This year we celebrate the 60th anniversary of the launch of the first artificial Earth satellite. Did this really happen? Was the satellite really launched into space? Or is everything rigged and we are being deceived?
It’s up to you to believe long-proven truths or become supporters of a shocking hypothesis. As they say, “trust but verify”! Whose side are you on?
People did not immediately learn that our planet has a spherical shape. Let's smoothly move back to ancient, ancient times, when people believed that the Earth was flat, and let's try, together with ancient thinkers, philosophers and travelers, to come to the idea of the Earth being spherical...
(This post is inspired by the thoughts of the author and blog guests to the message " How I improved my skills through courses. Part 2: How cartoons can harm our children")
The ideas of our distant ancestors about the Earth were mainly based on myths, traditions and legends.
Ancient Greeks They believed that the planet was a convex disk, similar to a warrior’s shield, washed on all sides by the Ocean River.
IN 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 tilted to 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.
Greek philosopher Thales(VI century BC) represented the Universe in the form of a liquid mass, inside of which there is a large bubble shaped like a hemisphere. The concave surface of this bubble is the vault of heaven, and on the bottom, flat surface The flat Earth floats like a cork. It is not difficult to guess that Thales based the idea of the Earth as a floating island on the fact that Greece is located on islands.
Contemporary of Thales - Anaximander imagined the Earth as a segment of a column or cylinder, on one of the bases of which we live. The middle of the Earth is occupied by land in the form of a large round island of Oikumene (“inhabited Earth”), surrounded by the ocean. Inside the Ecumene there is a sea basin that divides it into two approximately equal parts: Europe and Asia:
And here is the world in view ancient egyptians:
Below is the Earth, above it is the goddess of the sky;
to the left and to the right is the ship of the Sun god, showing the path of the Sun across the sky from sunrise to sunset.
Ancient Indians represented the Earth in the form of a hemisphere resting on elephants.
Elephants stand on the shell of a huge turtle standing on a snake and floating in the endless Ocean of milk. The snake, curled up in a ring, closes the near-earth space.
Please note that the truth is still far away, but the first step towards it has already been taken!
Residents of Babylon imagined the Earth in the form of a mountain, on the western slope of which Babylonia is located.
They knew that to the south of Babylon there was a sea, and to the east there were mountains that they did not dare cross. That’s why it seemed to them that Babylonia was located on the western slope of the “world” mountain. This mountain is surrounded by the sea, and on the sea, like an overturned bowl, rests the solid sky - the heavenly world, where, like on Earth, there is land, water and air.
A in Rus' They believed that the Earth is flat and is supported by three whales that swim in the vast ocean.
When people began to travel far, evidence gradually began to accumulate that the Earth was not flat, but convex.
For the first time, the assumption of the sphericity of the Earth said by the ancient Greek philosopher Parmenides in the 5th century BC
But first evidence This was given by three ancient Greek scientists: Pythagoras, Aristotle and Eratosthenes.
Pythagoras said that the Earth cannot have any other shape than a sphere. It can’t - and that’s it! Because, according to Pythagoras, everything in nature is arranged correctly and beautifully. And the most correct and therefore beautiful figure he was counting the ball. This is some kind of proof))))
First: If you look at a ship approaching from the sea, then first the masts will appear over the horizon and only then the ship’s hull.
But this proof did not satisfy many.
At night, a huge shadow “runs over” the Moon, and the Moon “goes out,” though not completely: it only darkens and changes color. The ancient Greeks said that the Moon becomes "the color of dark honey."
In general, the Greeks believed that a lunar eclipse was a very dangerous phenomenon for health and life, so it took a lot of courage from Aristotle. He observed lunar eclipses more than once and realized that the huge shadow covering the Moon is the shadow of the Earth, which our planet casts when it finds itself between the Sun and the Moon. Aristotle drew attention to one oddity: no matter how many times and at what time he observed a lunar eclipse, the Earth's shadow was always round. But only one figure has a always round shadow - the ball.
By the way, the next lunar eclipse will be... April 15, 2014.
In one source I found this interesting fragment with the words of Aristotle himself:
Three proofs of the spherical shape of the Earthwe find in Aristotle's book "On Heaven".
1. All heavy bodies fall to the ground at equal angles. This first Aristotelian proof of the sphericity of the Earth requires explanation. The fact is that Aristotle believed that heavy elements, to which he included earth and water, naturally tend to the center of the world, which therefore coincides with the center of the Earth. If the Earth were flat, then the bodies would not fall perpendicularly, for they would rush towards the center of the flat Earth, but since all bodies cannot be directly above this center, most bodies would fall to the earth along an inclined line.
2. But also (the sphericity of the Earth) follows from what is revealed to our senses. For, of course, lunar eclipses would not have such a shape (if the Earth were flat). The defining line during (lunar) eclipses is always arched. So, due to the fact that the Moon is eclipsed due to the Earth being between it and the Sun, the shape of the Earth must be spherical. Here Aristotle relies on the teaching of Anaxagoras about the cause of solar and lunar eclipses.The third famous scientist was Eratosthenes. He was the first to find out the size of the globe, thereby once again proving that the Earth has the shape of a ball.
3. Some of the stars are visible in Egypt and Cyprus, but are not visible in places further north. From this it is not only clear that the shape of the Earth is spherical, but also that the Earth is a sphere of small dimensions. This third proof of the sphericity of the Earth is based on observations made in Egypt by the ancient Greek mathematician and astronomer Eudoxus, who belonged to the Pythagorean Union.
The ancient Greek mathematician, astronomer and geographer Erastophenes of Cyrene (about 276-194 BC) determined the size of the globe with amazing accuracy. Now we know that on the day of the summer solstice (June 21-22), at noon, the Sun on the Tropic of Cancer (or Northern Tropic) is at its zenith, i.e. its rays fall vertically onto the surface of the Earth. Erastothenes knew that on this day the Sun illuminates the bottom of even the deepest wells in the vicinity of Siena (Siena- ancient name Aswan).
At noon he is in the shadow of vertical pillar, installed in Alexandria, 800 km from Siena, measured the angle between the pillar and the rays of the sun (Erastofen made a device for measurement - skafis, a hemisphere with a rod casting a shadow) and found it equal to 7.2 o, which is 7.2/360 fractions of a full circle, i.e. 800 km or 5,000 Greek stadia (1 stadia was approximately equal to 160 m, which is approximately equal to the modern 1 degree and, accordingly, 111 km). From here Erastophenes deduced that the length of the equator = 40,000 km (according to modern data, the length of the equator is 40,075 km).
Let's see what the textbook offers for fifth-graders:
Feel like ancient geographers!
Characteristic of this time are the ideas of the Byzantine geographer of the 6th century. Cosmas Indicoplova. A merchant and trader, Cosmas Indicopleus made long trading journeys throughout Arabia and eastern Africa. Having become a monk, Cosmas Indicopleus compiled a number of descriptions of his travels, including the only Christian topography that has reached us. He presented his fantastic picture of the structure of the Earth. The earth seemed to him in the form of a rectangle, stretched from west to east.
Referring to the Holy Scripture, he established the ratio of its length to width - 2: 1. The earth's rectangle is surrounded on all sides by the ocean, and along its edges there are high mountains on which the vault of heaven rests. The stars move along the vault, moved by the angels assigned to them. The sun rises in the east and disappears at the end of the day behind the mountains in the west, and during the night passes behind the mountain located in the north of the Earth. Internal structure Indikoplov was not interested in the lands of Kosma at all. They also did not allow any changes to the Earth's topography. Despite the obvious fantastic nature, Indikoplov’s cosmographic ideas were widespread in Western Europe, and later in Rus'.
Nicolaus Copernicus also contributed to the proof of the sphericity of the Earth.
He found that moving south, travelers see that in the southern side of the sky the stars rise above the horizon in proportion to the distance traveled, and new stars appear above the Earth that were not previously visible. And in the northern side of the sky, on the contrary, the stars descend towards the horizon and then completely disappear behind him.
In the Middle Ages, European geography, like many other sciences, entered a period of stagnation and rolled back in its development, incl. the fact that the Earth is spherical and the assumptions about the geolicentric model of the solar system are rejected. The main European navigators of that time - the Scandinavian Vikings - were not too interested in the problems of cartography, relying rather on their art of sailing the waters of the Atlantic. Byzantine scientists believed that the earth was flat, Arab geographers and travelers did not have clear views about the shape of the Earth, being primarily engaged in the study of peoples and cultures, rather than directly in physical geography.
Ignorants and religious fanatics brutally persecuted people who doubted that the Earth is flat and has an “end of the world” (and with the cartoon about Smeshariki, we seem to be returning to those times).
A new period of knowledge of the world begins at the end of the 15th century, this time is often called the era of the Great geographical discoveries. In 1519-1522, a Portuguese traveler Ferdinand Magellan(1480-1521) and his crew make the first trip around the world, which in practice confirms the theory that the Earth is spherical.
On August 10, 1519, five ships - Trinidad, San Antonio, Conception, Victoria and Santiago - set sail from Seville to circumnavigate the globe. Ferdinand Magellan was absolutely unsure of the happy ending of the voyage, because the idea of the spherical shape of the Earth was just an assumption.
The journey ended successfully - it was proven that the Earth is round. Magellan himself did not live to return to his homeland - he died on the way. But before his death he knew that his goal had been achieved.
Another proof sphericity can be served by the observation that when the Sun rises, its rays first illuminate clouds and other high objects; the same process is observed during sunset.
Also is evidence the fact that when you go up, your horizons increase. On a flat surface, a person sees around him for 4 km, at an altitude of 20 m already 16 km, from a height of 100 m his horizons expand to 36 km. At an altitude of 327 km, one can observe a space with a diameter of 4000 km.
Another proof sphericity is based on the assertion that all celestial bodies of our solar system have a spherical shape and the Earth is no exception in this case.
A photographic evidence sphericity became possible after the launch of the first satellites, which took photographs of the Earth from all sides. And, of course, the first person to see the entire Earth was Yuri Alekseevich Gagarin on April 12, 1961.
I think that the sphericity of the Earth has been proven!!!
Do you agree?
When writing this article, materials from textbooks and atlases on geography were used (according to the new Federal State Educational Standards, geography from grade 5):
Geography. 5-6 grades Workbook_Kotlyar O.G_2012 -32s
Geography. 5-6 grades Alekseev A.I. and others_2012 -192s
Geography. 5kl. Atlas._Letyagin A.A_2013 -32s
Geography. 5kl. Introduction to Geography. Domogatskikh E.M. and others_2013 -160s
Geography. 5kl. Beginner course. Letyagin A.A_2013 -160s
Geography. 5kl. Planet Earth_Petrova, Maksimova_2012 -112s,
as well as Internet materials.
None of the sources used
DOES NOT INCLUDE ALL EVIDENCE DESCRIBED AT THE SAME TIME!
The shape of the Earth - our home - has worried humanity for quite some time. Today, every schoolchild has no doubt that the planet is spherical. But it took a long time to get to this knowledge, going through church anathemas and the courts of the Inquisition. Today people are wondering who proved that the Earth is round. After all, not everyone liked history and geography lessons. Let's try to find the answer to this interesting question.
Excursion into history
Many scientific works confirm our thoughts that before the famous discovery of America by Christopher Columbus, humanity believed that it lived on a flat Earth. However this hypothesis does not stand up to criticism for two reasons.
- The great navigator discovered a new continent, and did not sail to Asia. If he had dropped anchor off the coast of real India, he could have been called the man who proved the sphericity of the planet. The discovery of the New World is not confirmation round shape Earth.
- Long before Columbus's epoch-making voyage, there were people who doubted that the planet was flat and presented their arguments as proof. It is likely that the navigator was familiar with the works of some ancient authors, and the knowledge of the ancient sages was not lost.
Is the Earth round?
Different peoples had their own ideas about the structure of the world and space. Before answering the question of who proved that the Earth is round, you should familiarize yourself with other versions. The earliest theories of worldbuilding claimed that the earth was flat (as people saw it). Movement heavenly bodies(sun, moon, stars) they explained by the fact that it was their planet that was the center of the Cosmos and the Universe.
IN Ancient Egypt The earth was represented as a disk lying on four elephants. They, in turn, stood on a giant turtle floating in the sea. The one who discovered that the Earth is round has not yet been born, but the theory of the sages of Pharaoh could explain the causes of earthquakes and floods, the rising and setting of the sun.
The Greeks also had their own ideas about the world. In their understanding, the earth's disk was covered with celestial spheres, to which stars were tied by invisible threads. They considered the moon and the sun to be gods - Selene and Helios. Nevertheless, the books of Pannekoek and Dreyer contain the works of ancient Greek sages who contradicted the generally accepted views of that time. Eratosthenes and Aristotle were the ones who discovered that the Earth is round.
Arab teachings were also famous for their accurate knowledge of astronomy. The tables of star movements they created were so accurate that they even raised doubts about their authenticity. The Arabs, with their observations, pushed society to change its ideas about the structure of the world and the Universe.
Evidence of the sphericity of celestial bodies
I wonder what motivated the scientists when they denied the observations of the people around them? The one who proved that the Earth is round drew attention to the fact that if it were flat, then the luminaries would be visible in the sky at the same time for everyone. But in practice, everyone knew that many of the stars that were visible in the Nile Valley were impossible to see above Athens. A sunny day in the Greek capital is longer than, for example, in Alexandria (this is due to the curvature in the north-south and east-west directions).
The scientist who proved that the Earth is round noticed that an object, moving away while moving, leaves only its upper part visible (for example, on the shore, the masts of a ship are visible, not its hull). This is only logical if the planet is spherical and not flat. Plato also considered the fact that a ball is an ideal shape to be a compelling argument in favor of sphericity.
Modern evidence for sphericity
Today we have technical devices that allow us not only to observe celestial bodies, but also to rise into the sky and see our planet from the outside. Here's some more evidence that it's not flat. As you know, during a lunar eclipse, the blue planet covers the night star with itself. And the shadow is round. And the various masses that make up the Earth tend downward, giving it a spherical shape.
Science and the Church
The Vatican admitted that the Earth is round rather late. Then, when it was impossible to deny the obvious. Early European writers initially rejected this theory as being contrary to Scripture. During the spread of Christianity, not only other religions and pagan cults succumbed to persecution. All scientists who conducted various experiments, made observations, but did not believe in one God, were considered heretics. At that time, manuscripts and entire libraries were destroyed, temples and statues, and objects of art were destroyed. The Holy Fathers believed that people do not need science, only Jesus Christ is the source of the greatest wisdom, and the holy books contain enough information for life. The geocentric theory of the structure of the world was also considered by the church to be incorrect and dangerous.
Kozma Indicopleustes described the Earth as a kind of box, at the bottom of which rested a stronghold inhabited by people. The sky served as a “lid”, but it was motionless. The moon, stars and sun moved like angels across the sky and hid behind high mountain. Above this complex structure The Kingdom of Heaven rested.
An unknown geographer from Ravenna described our planet as a flat object surrounded by an ocean, an endless desert and mountains, behind which the sun, moon and stars are hidden. Isidore (Bishop of Seville) in 600 AD in his works did not exclude the spherical shape of the Earth. The Venerable Bede was based on the works of Pliny, therefore he stated that the Sun more than Earth that they are spherical in shape, and that space is not geocentric.
Let's sum it up
So, returning to Columbus, it can be argued that his path was not based solely on intuition. Without wishing to diminish the merits of the great traveler, we can say that the knowledge of his era should have brought him to India. And society no longer rejected the spherical shape of our house.
The first idea about the Earth-sphere was expressed by the Greek philosopher Eratosthenes, who already measured the radius of the planet in the fourth century BC. The error in his calculations was only one percent! Ferdinand Magellan tested his guesses in the sixteenth century, making his famous trip around the world. Who proved that the Earth is round? Theoretically, this was done by Galileo Galilei, who, by the way, was sure that it was she who was spinning around the sun, and not vice versa.
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The Flat Earth movement has gained extraordinary momentum this year. Schoolchildren on Youtube tell each other that we live on a plane, and it is no longer clear whether they are joking or believing their words. The photographs are not convincing: they can easily be explained by a worldwide conspiracy. The time has come to take the child by the hand and make ironclad arguments in favor of the earthly sphere.
If Gagarin is not an authority for your child, and all the pictures with, in his opinion, are fakes, you will have to be patient and prove the sphericity, using a minimum of technical means - just like the ancient Greeks did. This process will be long, but extremely instructive.
1. We prove that the Earth is a disk or a ball
Let's start by deciding on the outlines of the native . Is it shaped like a suitcase or is there a turtle and elephants down there? There is a very simple way to understand that the Earth is a disk or a sphere. To do this, just wait for the full lunar eclipse(in Europe, the closest one can be observed on July 27, 2018, they occur every year. Go with your child to where the sky will definitely be clear on that day, and watch how the round shadow of the Earth slowly covers the Moon. Before that, demonstrate how the shape of the shadow depends from the shadow of an object - show a wolf or elk with the shadows of your hands on the wall. If the shadow is round, then the body that casts it is round.
After this, all that remains is to understand whether the earth has the shape of a disk or the shape of a ball.
2. Choose between a disk and a sphere
To answer the question of whether the Earth is flat or spherical, we will need: to get out of the city, a ball and an ant (beetle, ladybug or cockroach - your choice).
First, we need to find a tall, free-standing structure on flat terrain (for example, a power line pylon) and go from there. Just like a ship at sea, the support will not disappear from sight immediately, but gradually - first the “legs”, then the middle part and, finally, the top with the wires.
Now let's interpret the observation results. If we were dealing with high tower on a plane, then, moving away, it would become smaller and smaller, but, even remaining barely noticeable, it would be completely visible. On the surface of the sphere, objects gradually disappear from view.
We take a ball and put an insect on it. We bring the ball very, very close to the eyes so that the insect is half behind the “horizon” - the far visible edge of the ball. Only part of the animal’s body will be visible, just as only part of the tower is visible from afar. Now we can confidently conclude that we live on the surface of the earth (jokes aside).
3. Once again about the ball
Another great way to make sure that the earth is round - go out into the field at dawn. Take your watch with you and face the brightest edge of the sky. As soon as the edge (or - it doesn’t matter) appears over the horizon, lie down on the Earth and note the time. Look in the same direction. For a few seconds the star will disappear behind the horizon again. Why? Because you changed your viewing angle, and to a short time The Sun (or Moon) was hidden from you by the convex surface of the Earth.
The same can be done at sunset or watching the moon set, but only in the reverse order: first watch while lying down, and then while standing.
4. Determine the size of the ball
For the first time, the circumference of the equator was calculated by the librarian of the Library of Alexandria, Eratosthenes of Cyrene. The ancient sage compared the deviation of the Sun from the zenith on the same day of the year in two cities located at a distance of 800 kilometers from each other - Alexandria and Siena.
It is easy to catch the sun at its zenith: at this moment its rays fall even on the bottom of deep pits (Eratosthenes was guided by wells), and objects do not cast shadows. On the same day, the Sun cast sheer rays on Alexandria, but not on Sienna. It deviated from the zenith by 7.2°. Seven degrees from 360 is two percent. We multiply 800 by 50 and get 40 thousand (kilometers): this is the length of the Equator, this is confirmed by modern high-precision measurements.
Repeating Eratosthenes' experiment is quite simple, but you will have to enlist the help of friends in another city. Wait for the moment when the Sun is at its zenith (you can slack off and look on the Internet, you can navigate by sundial- a stick stuck into the ground. When the shadow is shortest, then the Sun is closest to the zenith). Above middle lane The sun is never at its zenith, but that doesn't matter. It is important at the moment when the shadow from your stick reaches its minimum, call your friends in a city located quite far from you - from Moscow, for example, to St. Petersburg, and ask them to measure the length of their shadow (and the height of the stick). Calculate the value of the acute angle between the stick and an imaginary straight line from the end of the stick to the end of the shadow in your place and in a distant city. Next - pure arithmetic: it should be about 40 thousand kilometers.
5. Once again measure the size of the ball
Let's return to experiments with clocks and sunrises (sunsets). We measured time for a reason: knowing it and your own height, you can solve the problem about the radius of the globe.
First, let's find the angle by which the Earth turned in the interval between the time you saw the edge of the rising Sun or Moon at dawn while standing and lying down. To do this, solve a simple proportion. If the Earth rotates 360° in 24 hours, what angle did it rotate during the time you recorded? Calculate and call it angle α.
Imagine that it was not you who fell and got up. Instead, the sunrise was observed by two people: Ivan 1 and Ivan 2, at such a distance from each other that the first saw the Sun later than the other by exactly the same time T. Two radii R to Ivan 1 and Ivan 2 form an isosceles triangle with angle α.
Complete the radius to Ivan 2 with a segment equal to your height h, and connect its end to the point where Ivan 1 stands. We get a right triangle with a hypotenuse R+h and a known acute angle. A little trigonometry and we calculate the radius of the Earth.