Is the sun near us in the morning or at noon???

More than 2,000 years ago, such a story was recorded in the book "Liezi":

One day, Confucius, a university scholar, met two children on the road debating the distance of the sun from the earth. A child said that the sun is near us at the beginning of its rise and far away from us at noon, because the rising sun is big and the sun at noon is small, and of course the big sun near is small and the far is smaller. The other said that the sun had just risen in the morning and it was colder, while at noon the sun was above us and the weather was milder, of course it was cold when the sun was far away from us, and hot when it was close to us.

Confucius listened to the argument of the two children, was stumped by this question, and felt that what they said made sense, so he had to shake his head and leave.

The question of Confucius in the Spring and Autumn Period is indeed too difficult for him. The development of modern astronomy has solved this mystery of nature. However, it is a bit complicated to answer this question very precisely.

When the Earth moves from aphelion to perihelion, of course, the sun at noon is closer to us every day than in the morning: on the one hand, since the average radius of the earth is 6,371 km, the sun at noon is facing us; On the other hand, since the movement of the earth is constantly approaching the sun, after half a day of movement, the great sun at noon is also closer to the earth than in the morning. However, when the Sun moves from perihelion to aphelion, the Earth is 30,000 kilometers away from the Sun on average every day, and about 8,000 kilometers away from the Sun for half a day from morning to noon, which is larger than the radius of the Earth, so that the Sun at noon is farther away from us than in the morning.

Therefore, the accurate answer is: from early January to early July every year, the morning is closer to us than the noon sun; From mid-July to late December, the sun is farther away from us in the morning than at noon.

In fact, this difference is so small that it is not visible to the naked eye compared to the distance between the earth and the sun, so it is generally believed that the sun is as far away from us in the morning as it is at noon.

So why does the morning sun look bigger than noon and warmer at noon than in the morning?

The sun appears to be bigger in the morning than at noon, which is caused by the illusion of the human eye. When the sun first rises, there is only a slightly brighter corner of the sky in the back of the village, and at noon, the background is a vast and clear sky. The illusion is formed because of the difference in the size and brightness of the surrounding area.

As for the difference between morning and noon temperatures, it is due to the fact that the morning sun passes obliquely through the atmosphere, and as a result, the heat energy is dispersed and reflected more.

Midday. The sun is the closest at noon in the day, because the highest point of the bulge of the spherical surface is the closest point from the sun, because the day changes with the seasons, so strictly speaking, a thin cylinder of a vertical disk is erected on the horizontal disk of the day, and when the cylinder is not projected by the sun, this is the closest time when the user is too far away from the user, that is, when the shadow is just under the feet, the sun is closest to the user.

It's not right, people often feel that the sun is big in the morning and evening, and small at noon, so they think that the sun is far away in the morning and evening, and close at noon. In fact, this kind of view is wrong.

In fact, the distance of the Sun from the Earth is basically constant. In the morning and evening, we feel that the sun is far away because the objects on the distant horizon, such as trees, are far away from us, and the perspective of our eyes is very small, and we feel that trees and the like are very small, and when we use them as references, we feel that the sun seems to be very large.

At noon, there are no distant objects above the head to refer to, and the objects above the head have a large angle of view to the eyes, and compared with them, the sun will feel that it is very large, but in fact, the size of the sun does not change, and the distance from the earth does not change.

None of them are right. The sun is the same distance from the earth in the morning and at noon. Why does the sun look bigger in the morning than at noon?

It's a visual error, an illusion. The same object, placed in a group of objects larger than it, appears small, while placed in a group of objects smaller than it appears large. In the same way, the morning sun rises from the horizon against the backdrop of trees, houses, distant mountains and a small corner of the sky, and in this comparison, the sun appears larger.

At noon, when the sun rises high and the vast sky is the backdrop, the sun appears smaller. Secondly, the white part of the same object appears larger than the black one, and this physical phenomenon is called "photoosmosis". When the sun is rising, the background is a dark and dreary sky, and the sun is exceptionally bright; At noon, the background is a blue sky, and the sun does not contrast much with its brightness, so it appears smaller.

The temperature is higher at noon than in the morning, is the sun closer to us at this time than in the morning? Neither is it. The main reason is that the sun hits the earth obliquely in the morning and the sun shines directly on the earth at noon.

At the same time and in the same area, direct radiation is higher than oblique heat. At the same time, at night, the heat of the sun shining on the ground dissipates, so it feels cool in the morning; At noon, the heat of the sun hits the ground, so it feels hot. The temperature is hot or cold, and it does not indicate how far or near the sun is from the ground.

So it's not right.

And also. In our northern hemisphere, in summer, the distance between the sun and the earth is hundreds of millions of kilometers; In winter, the distance between the Sun and Earth is slightly shorter, about 100 million kilometers. But this is the change in the distance between the sun and the earth in half a year.

And during the day, from morning to noon, the position of the Earth in its orbit changes very little. Therefore, the distance between the sun and the earth in the morning is almost exactly the same as the distance between the sun and the earth at noon. So why is the sun seen in the morning bigger than at noon?

This is because in the morning the sun is on the horizon, and there are some mountains, trees, and houses around it as a backdrop, and the sun appears larger against the backdrop of these smaller objects; At noon, when the sun is against the backdrop of a vast sky, the sun appears smaller. You can do an experiment by placing two objects of the same size, one between the smaller object and the other between the larger object, and the former object will feel larger than the next one.

Since the sun is almost as far away from us as it is in the morning, why does the midday sun make people feel hot, while the morning sun makes people feel hot without noon? This is because the sunlight hits the ground obliquely in the morning, the light is scattered, and the sunlight and heat per unit area of the ground are less; Moreover, before the sunlight reaches the ground in the morning, it travels a long distance in the atmosphere and is much weakened by the atmosphere, so we feel that the sunlight is weak in the morning; At noon, the sun rises the highest, and the angle of sunlight is the largest in the day, at this time, the sunlight that hits the ground is concentrated, and the sunlight and heat obtained on the ground per unit area are more, and before the sunlight disperses to the ground, the distance through the atmosphere is relatively short, and it is weakened by the atmosphere less, so we feel the intensity of the sun at noon, which makes people feel that the noon is hotter than the morning.