The Earth is a sphere, but why does it look flat?

This is mainly due to the horizon, which prevents the line of sight from being able to see far enough. In our eyes, it is a flat land, no wonder the ancients always believed that the earth was square and the sky was round。Why is this a thought?

Why is it that everyone knows that the earth is round, but the ground is very flat? Why are our eyes always deceiving themselves?

The ground under our feet, it's not flat, it's really a spherical surface. As we know in science, the earth is round, but why is the ground flat? Whether it's on the vast prairie or on the boundless seaWe can always see the horizon from a great distance, and this is because the earth is a circle, so the boundary that our eyes can only see is so far away.

For example, near the horizon of the sea, a ship came in the distance, and when we first saw it, it must have been the mast of a sailing ship, and it seemed to rise slowly from the bottom of the seaFrom here we know that it is because it is active at sea level, and it is like floating slowly from the bottom of the sea as if it is moving from the bottom of the sea.

For example, when we fly horizontally in the atmosphere, we feel that the plane is always in a straight motion. But if you go up a little higher, when you go into space, the astronauts there don't see it with their eyes, and in their eyes, we're on Earth, we're all moving in a circle, and that's because the observer's own gravity is so different that this qualitative change is caused. So there's no doubt that the Earth is round, but it's just that the Earth is too big for us to observe.

This must be just a plane of his**, so what you look at is flat.

The Earth is a sphere, but the Pacific Ocean is so big that it looks flat, but the fact it is not flat.

Because we can't see the Earth from a distance, it's flat up close.

Because the size of human beings is still too small for the earth, it is impossible to see the whole picture.

That's why things are different from every angle.

Because the Earth is so large, we can only see part of it.

Because the earth is so large, we can see only a limited amount of land, so it looks flat.

Modern people have completely become believers in scientific conclusions, and have no ability to think independently.

This is just a three-dimensional effect when taking pictures, so it looks flat.

This is because the Earth is big enough that people only see the horizon.

The angle between people's visual range and the center of the earth is too small, and the surface with a radius of tens of thousands of kilometers cannot be seen. The total area of the earth is about 500 million square kilometers, and your microscopic surface is a point, and you can't see the curved surface.

1. The sky is round.

2. According to the shape of the moon and the sun, the ancients determined that the earth is also a spherical body;

3. Magellan's first voyage determined that the earth is a sphere;

4. The satellites launched by humans take pictures in space, which confirms that the earth is a sphere.

The reason why the earth is round is because the gravitational force of the earth itself has the characteristics of centripetal, so the shape of the isotope plane formed by the centripetal gravitational force will be the shape of a spherical surface, so the shape of the earth will be round, after reaching a certain mass, most of the celestial bodies are round, and relatively small celestial bodies, such as only a few hundred million tons of weight, because the mass is not enough, the shape cannot form an obvious centripetal force, so there are all kinds of strange shapes.

In fact, strictly speaking, the shape of the earth should be elliptical, because there is a centrifugal force of rotation. The Moon is much rounder than the Earth.

It is a sphere with slightly deviated poles and a slightly bulging equator. Because the equatorial radius is 6,378 kilometers and the polar radius is 6,357 kilometers, the difference is 21 kilometers. It is about 6,650 with an average radius of 6371 km.

It is negligible on a globe, and therefore considers the Earth to be a sphere.

The average radius of the earth is 6,371 kilometers, the maximum circumference is about 40,000 kilometers, and the surface area is about 100 million square kilometers. However, it has been a long process to get this correct understanding.

Meaning:

The Earth's atmosphere is mainly made up of nitrogen and oxygen. The tropics receive more solar energy than the polar regions and redistribute it through atmospheric and oceanic circulation. Greenhouse gases also play an important role in regulating the surface temperature.

The climate of a region is determined not only by latitude but also by factors such as altitude and proximity to the region and the ocean. Severe weather such as tropical cyclones, thunderstorms, and heat waves often occur in a wide area and have a great impact on life.

Magellan's circumnavigation of the globe and the phenomenon of lunar eclipses can prove that the earth is a sphere.

According to the analysis of the lunar eclipse, the ancient Greek scholar Aristotle believed that the edge of the part of the moon that is obscured by the earth's shadow is arc-shaped, so the earth is a sphere or an approximate sphere. Magellan also made a voyage to prove that the earth is a sphere.

The development of awareness.

Ancient times. According to the analysis of the lunar eclipse, the ancient Greek scholar Aristotle believed that the edge of the part of the moon that is obscured by the earth's shadow is arc-shaped, so the earth is a sphere or an approximate sphere. Magellan also made a voyage to prove that the earth is a sphere.

Nowadays. Mankind has been exploring for a long time, and Magellan was the first to achieve a circumnavigation around the world, confirming that the earth is a sphere. With the development of human science and technology and the application of modern detection technology, people finally discovered that the earth is an irregular sphere with slightly flattened poles and slightly bulging equators.

Astronomy experts say that the Earth is indeed not an authentic sphere and that it looks a little strange. The reason why the earth grows like this is because it not only revolves around the sun, but also rotates at the same time, and the surface of the earth has both land and water, and in order to maintain the internal gravitational balance, under the "fight" of all parties, it grows into this strange shape.

The rotation of the earth and the tilt of the earth's axis have caused a variety of natural climatic environments on the earth (including the change of seasons, which is only one of them).

Due to the tilt of the Earth's axis, the direct point of the Sun is not on the equator for most of the year, and as a result of the rotation, the direct point of the Sun moves periodically between the Tropic of Capricorn throughout the year. As shown in the figure below: (Ye Fan takes the northern hemisphere as a benchmark) sedan shouting.

At the same time, the earth is an approximate sphere, and the uneven heating and the geostrophic deflection force caused by the rotation of the earth lead to the generation of different wind bands, and the combined effect of the revolution and the revolution produce a variety of climatic environments.

No! Our physics teacher stresses this issue all day long! Let's emphasize it to you

First of all, it is necessary to distinguish between gravity and gravitational force are two different concepts!

Then, you can explain it according to the concept!

Gravity is relative to the earth, which is the gravitational force of the earth on all things (it can also be understood as the gravitational force of all things on the earth, and the effect of force is mutual and always knows). When we study this problem, we think of the earth as a sphere, so its point of action is at the center of the sphere, which is the center of the earth, right? Then we can also know from the three elements of force that the force of gravitation is directed towards the center of the earth!

Secondly, gravity can be clearly known from the concept of high school textbooks, and the direction of the lead sensitive force is vertically downward!

And the relationship between gravity and gravitational force is actually that gravity is just a component of gravitational force!

This last concept may be difficult for you to understand, but remember, at this point, you can no longer think of the earth as a sphere!!

In fact, it is precisely because of the fact that when this concept is prescribed, there is a disagreement about whether or not to treat the earth as a sphere, and because these problems are avoided in the textbooks, they generally do not clearly explain the world, but only make ambiguities. That's why it eventually leads to problems like the landlord. In fact, beginners have this problem...

me，too！~

Report to the landlord, over, over!

The earth is not round, scientists after a long period of precise measurements, found that the earth is not a regular sphere, but an irregular elliptical sphere with slightly flattened equators at the poles, exaggeratedly speaking, a bit like a "pear", called a "pear-shaped body".

The effect of the Earth's rotation causes a slight flattening along the Earth's axis running through the poles and a slight uplift near the equator. From the Earth's core, the Earth's equatorial radius is 43 kilometers (27 miles) higher than its polar radius. Thus, the farthest point on the Earth's surface from the Earth's center of mass is not Mount Everest, the highest elevation, but the summit of Mount Chimborazo in Ecuador, located on the equator.

The Earth's reference spheroid has an average diameter of about 12,742 km (7,918 mi), which is approximately equal to (40,000 km) This integer is not a coincidence, but because the unit of length in the meter, which was originally defined as one-ten-ten-ten-millionth of the distance between the equator and the North Pole on the meridian passing through Paris, France.

The value of gravitational acceleration at a certain sea level at the equator is ga=, the value of gravitational acceleration at a certain sea level in the North Pole is gb=, the global standard value of gravitational acceleration is g=, and the earth's rotation period is 23 hours, 56 minutes and 4 seconds (sidereal days), that is, t=.

The Earth is an irregular elliptical sphere with slightly flattened poles and slightly bulging equators.

The Earth is supposed to be an ellipsoid.

First of all, human eyesight is limited, on average, you can see almost 8km (such vision is already very good), and the radius of the earth is 6337km, according to the arc length formula l=n (central angle) x (pi) x r (radius) 180 to calculate: n = degrees, you can compare what the concept of degrees is, almost negligible. Because the angle is too small to make a bend noticeable, it appears to be a flat surface.

In short, human eyesight is not far enough, if you can see 800km at a glance (equivalent to standing on the Bund in Shanghai and you can see Jinan Baotu Spring), you can feel that the earth is round.

It's round, but human beings are too short-sighted, and as far as the eye can see, it seems to be flat, so they mistake it for flat.

Because you are stupid, poor child (sympathetic eyes).