Lead
The Earth's orbit around the Sun is an elliptical orbit that is approximately elliptical, so the distance of the Earth from the Sun is constantly changing.
This closest point to the Sun is called perihelion, and the farthest point from the Sun is called aphelion, which is very correct.
However, there is a saying that in winter, the earth is at the perihelion position, and at this time, the earth is closer to the sun, so it is summer; Then in the summer, the earth is at aphelion, and at this time the earth is farther away from the sun, so it is winter.
So how exactly does this point of view be explained?
When the Earth is relatively close to the Sun, winter.
The fact is that when the earth is closer to the sun, winter is at this time, which is also a very correct point of view, and since this is the case, let's analyze how it is going on.
The time it takes for the earth to move around the sun is one year, and the orbit of the earth around the sun is an approximately elliptical orbit, in this elliptical orbit, the closest point to the sun, we call it perihelion, the perihelion is located at a distance of about 144 million kilometers, in fact, this distance is also very close.
For example, there are comets whose perihelion is 5 million kilometers away or even closer, and there are asteroids that even have perihelion less than 1 million kilometers from the Sun.
The farthest point from the Sun is called aphelion, and the aphelion is located at a distance of about 152 million kilometers.
There is a certain distance between the two, and this distance is about 80 million kilometers, is there only this distance?
In fact, more than that, the elliptical orbit will also change with a series of factors, so the distance of the elliptical orbit will also change.
This means that after the Earth has completed its orbit, the positions of perihelion and aphelion will change slightly.
So, where is the earth causing winter, and where is it causing summer?
The answer to this question is actually very simple, it is still the so-called inclination.
At the time of the winter solstice, at this time the earth is in the position of perihelion, so at this time, the earth is also relatively close to the sun, but because the trajectory of the earth's rotation is an inclined elliptical orbit, the angle of inclination of this elliptical orbit is about 23.44 °, so, in the first half of the year, the direct point of the sun is in the northern hemisphere, at this time the northern hemisphere is in a state of long days and short nights, at the summer solstice, the sun is just on the tropic of cancer, so the day length of the northern hemisphere is relatively long, Nights will be a little shorter.
So, winter and summer in the northern hemisphere are completely opposite, and winter and summer in the southern hemisphere are completely opposite.
In the northern hemisphere winter, the sun can shine directly on a certain place in the southern hemisphere of the earth, so the southern hemisphere is in a state of long days, and at this time it is also summer in the southern hemisphere.
Similarly, in the summer of the Northern Hemisphere, the sun shines directly on a certain place in the Northern Hemisphere, so the days are long in the Northern Hemisphere, so it is also summer at this time in the Northern Hemisphere.
Summer is at perihelion.
And in the summer, at this time the earth is at aphelion, so at this time, the earth is far away from the sun, when the earth moves on the equator, at this time the earth can get less energy from the sun per unit area, so on the equator, the temperature difference between day and night at this time is relatively large, which is also summer.
At this time, the direct point of the sun is also on the Tropic of Capricorn, so it is even more summer in the Northern Hemisphere.
The hottest place in the Northern Hemisphere, that is, near the equator, this place, is very hot all year round, and the Southern Hemisphere is also winter at this time, because the direct point of the sun in the Southern Hemisphere is on the Tropic of Capricorn at this time, so the Southern Hemisphere is colder at this time.
In the summer, due to the distance between the earth and the sun, the energy that can be obtained from the sun is relatively small, that is, the temperature is relatively low.
On the day of the winter solstice, the earth is at perihelion, but at this time, the temperature near the earth is also very low.
The temperature difference between the Earth and the Sun is very large, which causes the temperature to be very cold near the Earth, which is also the reason for winter.
So, whether it's winter or summer, the Earth is at perihelion.
It is a wrong idea that the earth causes winter at perihelion, and the real reason for winter is because of the angle between the earth and the sun, because the earth rotates every day, so every day, the earth will rotate once, and in the trajectory of the earth's rotation, at this time, the sun can shine directly on the southern hemisphere of the earth, so at this time the southern hemisphere is in summer, on the contrary, in the northern hemisphere it is winter.
So whether it's winter or summer, the Earth is at perihelion, and there will be no difference.
epilogue
When the Earth is at perihelion, it is closer to the Sun, so relatively speaking, there will be more energy near the Earth, which will become hotter nearby, which will increase the temperature nearby.