The earth is round or oval. Who said the earth is round
The fact that the shape of our planet is spherical, people did not immediately learn. Let's move smoothly back to ancient times, when people believed that the Earth was flat, and together with ancient thinkers, philosophers and travelers, let's try to come to the idea of the Earth's sphericity...
Ancient Greeks it was believed that the planet is 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 leaned towards the east. Therefore, all rivers in China flow to the east. The sky leaned to the west, so everything heavenly bodies moving 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 lower, flat surface, like a cork, the flat Earth floats. It is easy to guess that Thales based the idea of the Earth as a floating island on the fact that Greece is located on islands.
A contemporary of Thales - Anaximander represented 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 Oikumene 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;
on the left and on 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, based on elephants.
Elephants stand on the shell of a huge turtle standing on a snake and swimming 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!
Babylonians represented the Earth in the form of a mountain, on the western slope of which Babylonia is located.
They knew that there was a sea to the south of Babylon, and mountains to the east, which they did not dare to cross. Therefore, it seemed to them that Babylonia is located on the western slope of the "world" mountain. This mountain is surrounded by the sea, and on the sea, like an overturned bowl, the firm sky rests - the heavenly world, where, like on Earth, there is land, water and air.
A in Rus' believed that the Earth is flat and rests on three whales that swim in the vast oceans of the world.
When people began to make long journeys, evidence gradually began to accumulate that the Earth was not flat, but convex.
The first assumption about the sphericity of the Earth expressed 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 could not have any other form 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 counted the ball. Here is some kind of proof
First: if you look at a ship approaching from the sea, then first masts will appear from behind the horizon, and only then - the hull of the ship.
But this proof did not satisfy many.
At night, a huge shadow "runs" on 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 repeatedly observed lunar eclipses and realized that the huge shadow covering the Moon is the shadow of the Earth, which our planet casts when it is between the Sun and the Moon. Aristotle drew attention to one oddity: no matter how many times and at what time he observes a lunar eclipse, the shadow of the Earth is always round. But only one figure has a round shadow - the ball.
By the way, the next lunar eclipse will be... April 15, 2014.
In one source, I found such an interesting fragment with the words of Aristotle himself:
Three Proofs for the Earth's Sphericitywe find in Aristotle's book "On Heaven".
1. All heavy bodies fall to the ground at equal angles. This is the first Aristotelian proof of the sphericity of the Earth in need of explanation. The fact is that Aristotle believed that the heavy elements, among which he attributed 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, because they would rush to the center of the flat Earth, but since all bodies cannot be directly above this center, then 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, the eclipses of the Moon would not have such a shape (if the Earth were flat). The defining line during (lunar) eclipses is always arcuate. So, due to the fact that the Moon is eclipsed due to the location of the Earth between it and the Sun, the shape of the Earth must be spherical. Here Aristotle relies on the teachings 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 located to the 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 Erastofen of Cyrene (circa 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 the Northern Tropic) is at its zenith, i.e. its rays fall vertically on the surface of the Earth. Erastofen 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 measured the angle between the pillar and the rays of the sun in the shadow of a vertical pillar installed in Alexandria, 800 km from Siena (Erastofen made a device for measuring - skafis, a hemisphere with a rod casting a shadow) and found it equal to 7.2 o, which is 7.2 / 360 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 this, Erastofen 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 for fifth graders offers:
Feel like an ancient geographer!
Characteristic of this time are the views of the Byzantine geographer of the 6th century. Kosma Indikoplova. A merchant and trader, Cosmas Indikoplov made long trading trips across Arabia and East Africa. Having become a monk, Cosmas Indikoples compiled a number of descriptions of his travels, including the only Christian topography that has come down to us. He came up with 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 Holy Bible, he established the ratio of its length to width - 2: 1. On all sides, the earth's rectangle is surrounded by the ocean, and along its edges are located high mountains upon which the firmament rests. Stars move along the vault, which are moved by angels assigned to them. The sun rises in the east and hides 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 Kosma Indikoplova was not interested in the earth at all. They did not allow any changes in the relief of the Earth. Despite the obvious fantasticness, Indikoplov's cosmographic representations were very widespread in Western Europe, and later in Rus'.
Nicholas 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, enters a period of stagnation and rolls back in its development, incl. the fact of the sphericity of the Earth and the assumptions about the geolycentric model of the solar system are rejected. The main European navigators of that time - Scandinavian Vikings- were not too interested in the problems of cartography, relying rather on their art of sailing on the waters of the Atlantic. Byzantine scientists considered the earth to be flat, Arab geographers and travelers did not have unambiguous views about the shape of the Earth, being primarily engaged in the study of peoples and cultures, rather than directly in physical geography.
Ignorant and religious fanatics brutally persecuted people who doubt that the Earth is flat and that it has an "end of the world" (and with the cartoon about Smeshariki, we seem to be returning to those days).
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 team make the first trip around the world, which in practice confirms the theory of the sphericity of the Earth.
August 10, 1519 five ships - "Trinidad", "San Antonio", "Concepción", "Victoria" and "Santiago" sail from Seville to go around Earth. Fernando Magellan was absolutely not sure of the happy end of the voyage, because the thought of the spherical shape of the Earth was only an assumption.
The journey ended successfully - it was proved 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 observed that at sunrise, its rays first illuminate clouds and other high objects, the same process is observed during sunset.
Also is proof the fact that when you go up, your horizons increase. On a flat surface, a person sees around him for 4 km, at a height of 20 m it is already 16 km, from a height of 100 m the horizon expands by 36 km. At an altitude of 327 km, a space with a diameter of 4000 km can be observed.
One more proof sphericity is based on the assertion that all celestial bodies in our solar system are spherical in shape, and the Earth is no exception in this case.
A photo 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 who saw the whole Earth as a whole was Yuri Alekseevich Gagarin on 04/12/1961.
I think that the sphericity of the Earth is proved!!!
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 cells Notebook-workshop_Kotlyar O.G_2012 -32s
Geography. 5-6 cells Alekseev A.I. and others_2012 -192s
Geography. 5 cells Atlas._Letyagin A.A_2013 -32s
Geography. 5 cells Introduction to geography. Domogatskikh E.M. and others_2013 -160s
Geography. 5 cells Starting Course. Letyagin A.A_2013 -160s
Geography. 5 cells Planet Earth_Petrova, Maksimova_2012 -112s,
as well as Internet materials.
None of the sources used
DOES NOT INCLUDE ALL THE EVIDENCE DESCRIBED AT THE SAME TIME!
People have known for a long time that the Earth is round, and they are finding new and new ways to show that our world is not flat. And yet, even in 2016, there are quite a few people on the planet who firmly believe that the Earth is not round. This scary people, they tend to believe in conspiracy theories and are hard to argue with. But they exist. So does the Flat Earth Society. It becomes ridiculous at the mere thought of their possible arguments. But the history of our species has been interesting and quirky, disproving even firmly established truths. You don't have to resort to complicated formulas to dispel the flat earth conspiracy theory.
It is enough to look around and check ten times: the Earth is definitely, inevitably, completely and absolutely not 100% flat.
Today, people already know that the Moon is not a piece of cheese and not a playful deity, but the phenomena of our satellite explains well modern science. But the ancient Greeks had no idea what it was, and in search of an answer, they made some astute observations that allowed people to determine the shape of our planet.
Aristotle (who made quite a few observations about the spherical nature of the Earth) noticed that during lunar eclipses (when the Earth's orbit places the planet exactly between the Sun and the Moon, producing a shadow) the shadow on the lunar surface is round. This shadow is the Earth, and the shadow cast by it directly indicates the spherical shape of the planet.
Since the Earth rotates (look for information on the Foucault pendulum experiment if in doubt), the oval shadow that is produced during each lunar eclipse, says not only that the Earth is round, but also not flat.
Ships and horizon
If you have recently been to the port or just strolled along the beach, peering at the horizon, you may have noticed a very interesting phenomenon: Approaching ships don't just "appear" from the horizon (as they should if the world were flat), but rather emerge from the sea. The reason that ships literally "come out of the waves" is that our world is not flat, but round.
Imagine an ant walking on the surface of an orange. Looking at an orange close range, nose to the fruit, you will see how the body of the ant slowly rises above the horizon due to the curvature of the surface of the orange. If you do this experiment with a long road, the effect is different: the ant will slowly "materialize" into your field of vision, depending on how sharp your eyesight is.
constellation change
This observation was first made by Aristotle, who declared the Earth round, observing the change of constellations when crossing the equator.
Returning from a trip to Egypt, Aristotle noted that "stars are observed in Egypt and Cyprus, which were not seen in the northern regions." This phenomenon can only be explained by the fact that people look at the stars from a round surface. Aristotle went on to say that the sphere of the earth was "small in size, otherwise the effect of such a slight change of terrain would not have manifested itself so soon."
Shadows and sticks
If you stick a stick in the ground, it will cast a shadow. The shadow moves with the passage of time (based on this principle, the ancient people invented sundial). If the world were flat, two sticks in different places would produce the same shadow.
But that doesn't happen. Because the earth is round, not flat.
Eratosthenes (276-194 BC) used this principle to calculate the circumference of the earth with good accuracy.
The higher, the farther you can see
Standing on a flat plateau, you look towards the horizon away from you. You strain your eyes, then take out your favorite binoculars and look through them as far as your eyes can see (using binocular lenses).
Then you climb the nearest tree - the higher the better, the main thing is not to drop the binoculars. And again look, straining your eyes, through binoculars beyond the horizon.
The higher you climb, the further you can see. Usually we tend to associate this with obstacles on Earth, when you can’t see the forest behind the trees, and freedom behind the stone jungle. But if you stand on a perfectly clear plateau, with no obstructions between you and the horizon, you will see much more from above than from the ground.
It's all about the curvature of the Earth, of course, and this would not be the case if the Earth were flat.
Airplane flight
If you've ever flown out of a country, especially far away, you must have noticed two interesting facts about airplanes and the Earth:
Planes can fly in a relatively straight line for a very long time and do not fall over the edge of the world. They can also fly around the Earth non-stop.
If you look out the window on a transatlantic flight, you will in most cases see the curvature of the earth on the horizon. best view curvature was on the Concorde, but this aircraft has long been gone. From the new Virgin Galactic plane, the horizon should be absolutely curved.
Look at other planets!
The earth is different from others, and this is indisputable. After all, we have life, and we haven't found any planets with life yet. However, all planets have similar characteristics, and it would be logical to assume that if all planets behave in a certain way or exhibit specific properties - especially if the planets are separated by distance or formed at various circumstances- then our planet is similar.
In other words, if there are so many planets that formed in different places and in different conditions, but have similar properties, most likely, and our planet will be one. From our observations, it became clear that the planets are round (and since we knew how they formed, we know why they have such a shape). There is no reason to think that our planet will not be the same.
In 1610, Galileo Galilei observed the rotation of the moons of Jupiter. He described them as small planets revolving around big planet- and this description (and observation) did not please the church, as it challenged the geocentric model in which everything revolved around the Earth. This observation also showed that the planets (Jupiter, Neptune, and later Venus) are spherical and revolve around the Sun.
A flat planet (ours or any other) would be so incredible to observe that it would overturn virtually everything we know about planet formation and behavior. This will not only change everything we know about planet formation, but also about star formation (because our Sun should behave differently to accommodate the flat earth theory), speed and movement of celestial bodies. In short, we don't just suspect that our Earth is round - we know it.
The existence of time zones
It's 12 midnight in Beijing now, no sun. It's 12 noon in New York. The sun is at its zenith, although it is difficult to see it under the clouds. In Adelaide, Australia, one thirty in the morning. The sun will rise very soon.
This could be explained only by the fact that the Earth is round and rotates around its own axis. At a certain moment, when the sun is shining on one part of the Earth, it is dark at the other end, and vice versa. This is where time zones come from.
Another moment. If the sun were a "spotlight" (its light fell directly on a specific area), and the world was flat, we would see the sun even if it did not shine above us. In much the same way, you can see the spotlight on the stage of the theater, while remaining in the shadows yourself. The only way to create two completely separate time zones, one of which will always be in the dark, and the other in the light, is to acquire a spherical world.
Center of gravity
Eat interesting fact about our mass: it attracts things. The force of attraction (gravity) between two objects depends on their mass and the distance between them. Simply put, gravity will pull towards the center of mass of objects. To find the center of mass, you need to study the object.
Imagine a sphere. Due to the shape of the sphere, wherever you stand, there will be the same amount of sphere under you. (Imagine an ant walking on a glass ball. From the ant's point of view, the only sign of movement will be the movement of the ant's legs. The shape of the surface will not change at all.) The center of mass of a sphere is at the center of the sphere, meaning gravity pulls everything on the surface towards the center of the sphere (straight down), regardless of the object's location.
Consider a plane. The center of mass of the plane is at the center, so the force of gravity will pull everything on the surface towards the center of the plane. This means that if you are on the edge of the plane, gravity will pull you towards the center, and not down, as we are used to.
And even in Australia, apples fall from top to bottom, not from side to side.
Pictures from space
In the last 60 years of space exploration, we have launched many satellites, probes and people into space. Some of them have returned, some continue to stay in orbit and transmit beautiful images to Earth. And in all the photographs, the Earth (attention) is round.
If your child asks how we know the earth is round, take the trouble to explain.
All of us, from the school bench, were “driven” into the head that our planet is round, but we are forced to take our word for it. If you are told: give evidence of the sphericity of the Earth, then many will be puzzled by such a question. Even now, in 2017, there are many societies where people truly believe that our planet is flat and limited by the glaciers behind which we hide. uncharted lands. As a rule, these people believe in a conspiracy theory that they are all deceived and do not disclose information on pain of death. They also put forward a lot of dubious evidence that is based on unverified calculated data. So, our task in this work is to dispel all myths and give 5 proofs of the sphericity of the Earth. To check this, it is enough to look around with the naked eye and make sure many times that our planet is not flat with a hundred percent probability!
Proof 1. Moon
The first evidence of the sphericity of the Earth was presented in the distant past by Aristotle, and it was based on a lunar eclipse. So, earlier people, since they were not educated, believed that our Moon is some kind of deity that plays with us like that. Some ancient Greeks were able to determine precisely from the Moon that our planet has the shape of a ball.
In addition, Aristotle was able to prove that, in addition to being round, it is also spherical. The evidence was elementary. A lunar eclipse is the moment when on the moon it is possible to see the shadow of our planet, from which it is easy to determine that the Earth has the shape of a ball.
Proof 2. Embankment
Try it yourself, give evidence of the sphericity of the Earth by observing the ships. Many people like to walk along the embankment, especially beautiful moments - this is a ship slowly rising above the water, it seems that it is literally coming out of the water. Why do you think this visual illusion occurs? Everything is very simple, this is another proof of a round planet.
Try an experiment, take an orange or any other round fruit or vegetable and plant an ant on it. As he rises, he will slowly appear. If you plant the same ant on a flat surface, it will look a little different, the ant will gradually materialize.
Proof 3. Stars
As in the case of the Moon, this discovery was made by Aristotle, observing the change of constellations, and a trip to Egypt helped him. Returning from his trip, he noticed that the constellations there and in the northern regions are very different, and this can only be explained by the fact that we are not looking at the sky from a flat surface.
Try to trace it yourself empirically give evidence of the sphericity of the Earth, because many, especially in summer time, go on trips, so spend this time to your advantage. There is such a pattern - the farther you move away from the equator, the more the constellations familiar to us go to the horizon.
Proof 4. Horizon
Try and give proof of the sphericity of the Earth through observation. Just look into the distance, what do you see? And try to climb higher, what then will you see? This experiment is best done not in an urban area, so that high-rise buildings do not interfere with the view.
In principle, this experiment is very similar to the second, where we observed the ships. The higher you climb, the more you will see, this is due to the fact that the Earth is not flat, if it were otherwise, there would be no such effect.
Proof 5. Sun
If you are in this moment noon, then reverse side planets midnight. How can this be explained? The earth is round, if the planet were flat, and the Sun was a kind of searchlight, then we would observe our luminary for many kilometers, even if we ourselves remained in the shade.
During the life of Columbus, people believed that the Earth was flat. They believed that in Atlantic Ocean huge monsters live, capable of swallowing their ships, and there are terrible waterfalls on which their ships will perish. Columbus had to fight these strange notions to convince people to go sailing with him. He was convinced that the earth was round.
— Emma Miler Bolenius, author of American textbooks, 1919
One of the longest-lived myths children grow up believing in [ author - American - approx.transl.], is that Columbus was the only one of the people of his time who believed that the Earth was round. The rest believed that she was flat. “How brave the navigators of 1492 must have been,” you think, “to go to the end of the world and not be afraid to fall off it!”
Indeed, there are many ancient references to the earth in the form of a disk. And if of all celestial bodies if you knew only the Sun and the Moon, you could come to the same conclusion yourself.
If you go outside at sunset, a day or two after the new moon, you can see something like this.
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 out on the following days and watch what happens next.
Not only does the moon change position by about 12 degrees each night as it moves further away from the sun, it's getting brighter! You could (fairly) conclude that the Moon revolves around the Earth, and that the change in phases is due to the light from the Sun shining on different parts of the round Moon.
Ancient and modern views on the phases of the moon coincide in this.
But about twice a year during a full moon, something happens 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 bent 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 decided in the XV or XVI centuries(when Magellan made a trip around the world), but about 2000 years ago, in ancient world. And what is most surprising, for this it took only the Sun.
If you track the path of the Sun in the daytime sky while living in the northern hemisphere, you will notice that it rises in the eastern part of the sky, rises to a maximum in the south, and then declines and sets in the west. And so on any day of the year.
But the paths throughout the year are slightly different. The sun rises much higher and shines for more hours in summer, and in winter it rises lower and shines less. See photo for illustration. solar path, made during the winter solstice in Alaska.
If you plot the path of the sun across the daytime sky, you will find that the lowest of the paths, and the shortest in time, falls on winter solstice– usually December 21st – and the highest (and longest) way is around the summer solstice, usually June 21st.
If you make a camera capable of photographing the path of the Sun across the sky over the course of a year, you end up with a set of arcs, the highest and longest of which was taken 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. There, in particular, it was said that on the day of the summer solstice:
Shadow of a man looking in deep well, will cover the reflection of the Sun at noon.
In other words, the Sun will be directly overhead, not deviating a single degree to the south, north, east or west. And if you had a completely vertical object, it wouldn't cast shadows.
But Eratosthenes knew that this was not the case in Alexandria. The sun approaches its highest point at noon during the summer solstice in Alexandria closer than on other days, but vertical objects there also cast a shadow.
And like any good scientist, Eratosthenes set up an experiment. By measuring the length of the shadow cast by a vertical stick on the day of the summer solstice, he was able to measure the angle between the Sun and the vertical direction in 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 the Sun's rays can be parallel, and the Earth can be curved!
If then he could find out the distance from Alexandria to Syene, knowing the difference in angles, he could calculate the circumference of the Earth! If Eratosthenes were the supervisor of a graduate student, he would have sent him on his way to measure the distance!
But instead he had to rely on the then known distance between the two cities. And the most accurate method of measurement then was ...
Camel travel. One can understand the criticism of such accuracy. And yet, he considered the distance between Syene and Alexandria to be 5,000 stadia. The only question is the length of the stage. The answer depends on whether Eratosthenes, a Greek who lived in Egypt, used the Attic or Egyptian stages, which historians are still arguing about. The Attic stadia was used more often and is 185 meters long. Using this value, you can get the circumference of the Earth equal to 46,620 km, which is 16% more than the real value.
But the Egyptian stadia is only 157.5 meters, and perhaps this is what Eratosthenes had in mind. In this case, you get 39,375, which is different from contemporary 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 used to this day, 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 ideas 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 proof of the Earth's curvature would not come until 1946!
By knowing the shape and size of the Earth, as early as 240 BC, we have been able to figure out a lot of wonderful things, including the size and distance of the Moon! Therefore, we give credit to Eratosthenes for discovering that the Earth is round and for the first accurate calculation of its size!
If there is one thing that Columbus should be remembered for in relation to the size and shape of the Earth, it is for using too small values for its circumference! His estimates of the distances by which he convinced that a ship could pass from Europe directly to India (if the Americas did not exist) were incredibly small! And if there were no Americas, they and the team would die of starvation before reaching Asia!
We live in an amazing time. Most of the celestial bodies in the solar system have been explored by NASA probes, GPS satellites are circling the Earth, ISS crews are flying steadily into orbit, and returning rockets are landing on barges in the Atlantic Ocean.
Nevertheless, there is still a whole community of people who are sure that the Earth is flat. Reading their statements and comments, you sincerely hope that they are all just trolls.
Here are some simple proofs that our planet is round.
Ships and horizon
If you visit any port, look at the horizon and watch the ships. As a ship moves away, it doesn't just get smaller and smaller. It gradually disappears behind the horizon: first the hull disappears, then the mast. Conversely, approaching ships do not appear on the horizon (as they should if the world were flat), but rather come out of the sea.
But ships do not emerge from the waves (with the exception of " Flying Dutchman" from " "). The reason why approaching ships look like they're slowly rising from the horizon is because the Earth isn't flat, it's round.
Varying constellations
Paranal Observatory in ChileDifferent constellations can be seen from different latitudes. This was noticed by the Greek philosopher Aristotle as early as 350 BC. e. Returning from a trip to Egypt, Aristotle wrote that "in Egypt and<…>there are stars in Cyprus that are not visible in the northern regions.
The most striking examples are the constellations Ursa Major and the Southern Cross. Ursa Major, a bucket-like constellation of seven stars, is always visible at latitudes above 41° north latitude. Below 25° south latitude you won't see it.
Meanwhile, the Southern Cross, a small constellation of five stars, you will find only when you get to 20 ° north latitude. And the further south you move, the higher the Southern Cross will be above the horizon.
If the world were flat, we could observe the same constellations from anywhere on the planet. But it's not.
You can repeat Aristotle's experiment when you travel. Find the constellations in the sky will help you these for Android and iOS.
Lunar eclipses
Stages of a lunar eclipse / wikimedia.org Another proof of the sphericity of the Earth, found by Aristotle, is the shape of the earth's shadow on the moon during an eclipse. During an eclipse, the Earth is between the Moon and the Sun, blocking the Moon from sunlight.
The shape of the Earth's shadow that falls on the Moon during an eclipse is perfectly round. That is why the moon becomes a crescent.
Shadow length
The first to calculate the circumference of the earth was a Greek mathematician named Eratosthenes, who was born in 276 BC. e. He compared the length of the shadows on the day of the summer solstice in Syene (this Egyptian city is today called Aswan) and Alexandria located north.
At noon, when the sun was directly over Siena, there were no shadows. In Alexandria, a stick placed on the ground cast a shadow. Eratosthenes realized that if he knew the angle of the shadow and the distance between cities, he could calculate the circumference of the globe.
On a flat earth, there would be no difference between the length of the shadows. The position of the Sun would be the same everywhere. Only the sphericity of the planet explains why the position of the Sun is different in two cities at a distance of several hundred kilometers from each other.
Observations from above
Another obvious proof of the sphericity of the Earth: the higher you go, the farther you can see. If the earth were flat, you would have the same view regardless of your elevation. The curvature of the Earth limits the range of our view to about five kilometers.
World travel
View from the cockpit of the Concorde / manchestereveningnews.co.uk The first circumnavigation of the world was made by the Spaniard Ferdinand Magellan. The voyage lasted three years, from 1519 to 1522. It took Magellan five ships (of which two returned) and 260 crew members (of which 18 returned) to circumnavigate the globe. Fortunately, in our time, in order to make sure that the Earth is round, it is enough just to buy a plane ticket.
If you've ever traveled by plane, you may have noticed the curvature of the Earth's horizon. It is best seen in flight over the oceans.
According to article Visually discerning the curvature of the Earth, published in the journal Applied Optics, the curve of the Earth becomes visible at an altitude of about 10 kilometers, provided that the observer has a view of at least 60 °. From the window of a passenger airliner, the view is still less.
More clearly, the curvature of the horizon is visible if you fly above 15 kilometers. It is best seen in photographs from the Concorde, but, unfortunately, this supersonic aircraft has not flown for a long time. However, high-altitude aviation is reviving in the passenger rocket plane from Virgin Galactic - Space Ship Two. So in the near future we will see new photos of the Earth taken in suborbital flight.
An airplane can easily circle the globe without stopping. World travel have been carried out on aircraft several times. At the same time, the planes did not detect any "edges" of the Earth.
Weather balloon observations
Image from weather balloon / le.ac.uk Ordinary passenger airliners fly not so high: at an altitude of 8-10 kilometers. Weather balloons rise much higher.
In January 2017, students at the University of Leicester tied several cameras to hot air balloon and launched it into the sky. It rose to a height of 23.6 kilometers above the surface, significantly higher than passenger airliners fly. In the pictures taken by the cameras, the curve of the horizon is clearly visible.
Shape of other planets
Photo of Mars / nasa.gov Our planet is pretty ordinary. Of course, there is life on it, but otherwise it is no different from many other planets.
All our observations show that the planets are spherical. Since we have no good reason to think otherwise, our planet is also spherical.
A flat planet (ours or any other) would be an incredible discovery that would contradict everything we know about planet formation and orbital mechanics.
Time Zones
When it's seven in the evening in Moscow, it's noon in New York, and it's midnight in Beijing. In Australia at the same time, 1:30 am. You can see what time it is anywhere in the world, and make sure that the time of day is different everywhere.
There is only one explanation for this: the Earth is round and rotates around its axis. On the side of the planet where the Sun shines, it is currently day. Opposite side The earth is dark, and there is night. This forces us to use time zones.
Even if we imagine that the Sun is a directional searchlight that cruises over a flat Earth, then we would not have a clear day and night. We would still observe the Sun, even if we were in the shade, as we can see the spotlights shining on the stage in the theater, while being in a dark hall. The only explanation for the change in time of day is the sphericity of the Earth.
Center of gravity
It is known that gravity always pulls everything towards the center of mass.
Our Earth is spherical. The center of mass of the sphere is located, which is logical, in its center. Gravity pulls all objects on the surface in the direction of the Earth's core (that is, straight down) regardless of their location, which is what we always observe.
If we imagine that the Earth is flat, then gravity will have to attract everything on the surface to the center of the plane. That is, if you find yourself at the edge of a flat Earth, gravity will not pull you down, but to the center of the disk. It is hardly possible to find a place on the planet where things fall not down, but sideways.
Images from space
Photo from the ISS / nasa.gov The first photograph of the Earth from space was taken in 1946. Since then, we have launched many satellites, probes and astronauts (or astronauts or taikonauts - depending on the country) there. Some satellites and probes have returned, some remain in Earth orbit or fly through solar system. And in all the photos and videos shared spacecraft, the earth is round.
The curvature of the Earth is clearly visible in photographs from the ISS. In addition, you can see photographs of the Earth, which are made at intervals of 10 minutes by the satellite of the Japan Meteorological Agency Himawari-8. It is constantly in geostationary orbit. Or here are real-time photos from the DSCOVR satellite, NASA.
Now, if you suddenly find yourself in a flat earth society, you will have several arguments in arguing with them.
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