If people had the opportunity to travel in space, from planet to planet, how carefully it would be necessary to think through everything. Up to food, temperature and personal hygiene. Hollywood is replete with films dedicated to the space theme, in which people in outer space finally lost their chances of life. Everyone saw the picture when the stiffened spacesuit was carried out along the orbit. Why is space cold? After all, in the orbit of the earth there are many astronauts who went into outer space, and they remained safe and sound.
Is it cold in space?
Suppose that we are as far away from the celestial bodies, which with their energy and temperature are able to act on the material body. We also isolate ourselves from planets and their satellites, which are able to affect the temperature of their core. Subject to these points, the temperature will be -274 degrees Celsius. This temperature is called absolute zero, that is, the temperature cannot be lower than it in nature. Why is space cold? - because this is the only place where the temperature drops to absolute zero.
In everyday realities, temperature cannot have a value below zero. The exception is only the most remote parts of the universe. In the orbit of the earth, taking into account all factors, the temperature is approximately - 4 degrees Celsius.
What happens when absolute zero
Absolute zero is the zero temperature on the Kelvin scale. Under standard conditions, such a temperature is not possible. The coldest temperature in space is -274 (Celsius) or 0 (Kelvin). So why is the temperature not able to cross the border?
According to the third law of thermodynamics, which was agreed by Nernst, when the temperature tends to its absolute zero, the entropy of the system (or body), the heat capacity and the coefficient of thermal expansion tend to it. If the temperature reaches absolute zero, then the process of chaotic motion of atoms and molecules stops. From the point of view of thermodynamics, the body breaks up into molecules. And from the point of view of quantum physics, zero vibrations continue to occur in the body. It is these judgments that help answer the question: "Why is it cold in space?"
Physicists from Yale University conducted an experiment on strontium monofluoride (SrF). A molecule was placed in a magnetic field, which constantly lost its energy and, ultimately, as close to absolute zero as possible, the molecule decayed into atoms.
Thanks to studies of temperatures close to absolute zero, the effect of superconductivity was obtained, which is widely used in industry and science.
Transferring the situation to outer space, we can say that achieving absolute zero is hampered by radiation from the stars.
Types of heat transfer
The school course in physics deals with the section of thermodynamics, which pays attention to the types of heat transfer. This section of physics will help answer the question "why is it colder in space than on earth."
There are three types of heat transfer in nature:
- Thermal conductivity. This is the transition of energy from a warmer body or part of the body to a less heated one. It should be noted that it is impossible to transfer energy from colder to less cold (according to the principle of the second law of thermodynamics). Example: heating a metal body.
- Convection. Energy is transmitted by streams (jets). Example: heat transfer in a room between cold and warm air.
- Radiation. Energy is transmitted through electromagnetic waves. Example: solar heat.
Since space is a vacuum (the density of molecules in space is negligible - 10 ^ -31 g / cm ^ 3), it should be assumed that the only possible option for heat transfer is radiation. Earth is not a vacuum, it has an atmosphere (molecules on the surface of the planet), which allows three types of heat transfer at once.
The dependence of temperature on body position
Radiation in space comes from heated bodies, in our galaxy it is the Sun. The sun sends electromagnetic waves from its surface, which have a direct trajectory of motion. Consequently, the body receives energy if the Sun is in range.
If electromagnetic waves hit the object, the body absorbs thermal energy. But exchange with the environment will not take place, since the body is surrounded by a vacuum, which has practically no molecules.
If the object is, for example, beyond the dark side of the planet, where electromagnetic waves cannot get, then the body will really cool, striving for absolute zero.
Therefore, a heat-resistant coating is applied to the surface of space stations and spacesuits.
