The earth is the home of human beings, but only with the sun, the earth can be for human habitation.
Earth's supply of all sources of energy from the sun, even if it's buried fossil energy, can also rely on the sun become the coal and oil, we use the sun's surface temperature up to 6000 ℃, its energy in the form of light and heat is transmitted to the earth, even now have the ability to do out of the earth, people left the sun is still difficult to survive.
However, there is a phenomenon that makes people confused. The surface temperature of the earth exposed to the sun can reach up to 70℃. After the sunlight hits the earth, even the earth is hot, but the space between the sun and the earth is still cold, which is only 270℃ below zero.
If the sun heats the Earth as it spreads its energy, why is the journey between them still cold?
How exactly is this energy transferred?
Mercury is the closest planet to the sun. It is on the side facing the sun and can reach temperatures as high as 428 degrees Celsius, but on the dark side facing away from the sun it can reach -190 degrees Celsius. So close to the sun, the difference in temperature can be so large, which must be talked about heat transfer and human definition of temperature 39bet-kết quả bóng đá-kết quả xổ số miền bắc-kèo bóng đá -soi cầu bóng đá-đặt cược.
Defined in ordinary people's view, the temperature is very simple, it is ok to use thermometer, but this is not a direct measurement method, but by objects indirectly come out the results of the temperature change characteristics, such as when the temperature is the most commonly used measurement of mercury, mercury will happen after heated regularity of inflation, rising through expansion of the scale, we concluded that the temperature reached a certain value.
In fact, from the perspective of molecular motion theory, temperature is just a sign of the average kinetic energy of molecular motion of objects, which is the collective performance of a large number of molecular motions. When we measure temperature, we actually measure the thermal motion state of particles at this time. The more intense the particle motion, the higher the temperature will be, and vice versa.
When the sun shines directly on us, we feel warm, which is actually the action of the sun's photons.
Everything is made up of elementary particles, but each particle moves to a different degree, so different things in the same place on the Earth will have different temperatures. For example, if the ground and the atmosphere receive the same amount of heat energy from the sun, the surface will be significantly hotter than the atmosphere.
This is because soil and rock have a higher density of material, while the atmosphere is less dense and the motion of natural particles is less intense.
Now that you know what temperature really means, what does heat travel through? Why can't you heat a vacuum?
The first method of heat transfer
And the most direct way is heat transfer, which is generally the transfer of heat between solids through contact. For example, when you hold a glass of hot water in your hand, your hand will feel hot and hot. This is the reverse transfer of heat, which means that as long as there is a temperature difference, heat will be transferred between the two.
The second way is heat convection.
It occurs mainly between fluids such as gases and liquids, which, as they move, carry with them the heat of the movement of the molecules of the fluid itself. For example, when you boil water, the temperature inside the liquid is not uniform, resulting in different temperatures and pressures, which causes the liquid to circulate, so that the heat is evenly transferred to all parts of the water.
The last is the main way the Earth receives energy from the sun: thermal radiation.
The main difference between it and the first two modes of transmission is that heat radiation does not require an intermediate medium. Heat conduction requires solid contact, heat convection requires the contact of heat-carrying particles, but heat radiation does not require any medium, it can travel in a vacuum and loses little energy, whereas the sun transmits heat mainly through visible and infrared light.
There are no particles in a vacuum, and the motion of the particles is the source of heat, and the sun, which radiates heat through the vacuum, cannot heat the particles, but in that case, why doesn't the vacuum reach absolute zero? Are there stars that are far away from the sun that have absolute zero degrees?
As we said above, the essence of temperature is the thermal motion between particles, and absolute zero means that the particles are moving to zero, at complete rest.
Pluto is so far away from the Sun that scientists once thought it was the coldest place in the solar system and that absolute zero would exist there, but a probe launched by humans has revealed that not only is there no absolute zero on Pluto's surface, it's even warmer than space, with a temperature of minus 229 degrees Celsius.
It turns out that even though it's far enough away from the sun, it's still in the sun's energy system. Even if the amount of energy received is very small, but it's still there, as long as the heat is received, the particles in Pluto's interior will be in motion and will not be able to reach absolute zero.
In order to get to absolute zero, at least one of the following conditions must be met: one is that the particles inside the matter are not receiving any heat, and the other is that there is no matter in the space, and without matter there is no thermal motion of the particles.
Although space looks empty, there is still a small amount of dusty matter. If there is no dust at all, would there be absolute zero degrees?
The answer is no, because in space where there isn't even dust, there's dark matter that we can't see, and modern science says that dark matter makes up the bulk of the universe.
Perhaps the particles flying inside the dark matter contribute to the temperature above absolute zero in the seemingly empty universe.