The surface of the sun is close to 5500 ℃, the earth is hot, why is space close to absolute zero?

The basic conditions for life to exist are harsh, one of which is that it must have a suitable temperature. Speaking of which, we must also thank the sun hanging in the sky. It is precisely because of the sun's illumination that the earth can have a temperature suitable for life to survive, and the earth can be so prosperous. Of course, just having the sun is not enough, and the distance between us and the sun is also very important. If it is too far, it will naturally be too cold, but if it is closer, I am afraid that the earth will be roasted. Because the sun is too hot. So how hot is the sun? If we use the familiar Celsius to express, then it is about 5500 degrees, which is just the temperature of the surface of the sun.

According to scientists' speculation, the temperature of the center of the sun may reach 20 million degrees Celsius. My God, 20 million degrees Celsius, if it wasn't for Hou Yi shooting down nine suns, the 200 million degrees Celsius combined by the ten suns would be terrifying. Of course, this is just a joke. It is because of these 20 million degrees Celsius and the suitable distance that the earth is prosperous and comfortable. When there is high temperature, there will be low temperature. Compared with the high temperature of the sun, the low temperature in space is particularly obvious. As far as our solar system is concerned, the lowest temperature can reach minus 272 degrees Celsius, which is very close to the absolute temperature of minus 273.15 degrees Celsius. It's zero. So if people are exposed to space, I am afraid they will freeze to death in an instant.

However, this is very strange. The temperature of the sun, the center of the solar system, is so high that even the earth, which is 150 million kilometers away from the sun, is illuminated so warmly. Why is it so cold in space? This is really a bit confusing. But if you figure out the nature of temperature, it's not surprising. What is the nature of temperature? From the point of view of physics, the essence of any temperature is the intensity of the movement between molecules. The faster the movement between molecules, the higher the temperature, and vice versa. The molecules themselves are in motion all the time, but the speed is different, but it cannot be completely stopped. This is also the essential reason why absolute zero cannot be achieved, because absolute zero of minus 273.15 degrees Celsius describes the state of molecules when they are completely at rest.

But even if it is a cold and static stone, the molecules inside it cannot be completely stagnant, and are still in slow motion. After clarifying the nature of temperature, let's go back and look at the above problem. The reason why space is called space is truly worthy of the name, because it is really space. Space is almost a vacuum state. The number of molecules in space is very small, and the density is very low. We said that the essence of temperature is the intensity of intermolecular motion, and there are not even a few molecules in space, so how can they move? There's no heat without motion, so even a blazing sun nearby won't help. Then, a new question arises. Since space is close to a vacuum, how is the heat from the sun transmitted to the earth?

In fact, it is not accurate to describe it by conduction. There are many different ways of heat transmission. Let’s take a look at science first. Any substance will radiate electromagnetic waves, which can be as small as a particle or as large as the sun. The way the sun transmits heat to the earth is thermal radiation. Heat is radiated to the earth in the form of electromagnetic waves. Conduction. Therefore, our earth has a suitable temperature. Of course, another factor is also very important, that is, the atmosphere. It is because of the protection of the atmosphere that we can save the heat from the sun. It is for this reason that We'll find that cloudy nights are warmer than sunny nights because the atmosphere is more insulated on cloudy days.