The temperature at the surface of the sun can reach 6000°C, but the temperature between the sun and the earth is only minus 270°C.
Then the temperature of the Earth's surface can reach up to 55°C at its hottest.
So the question is, how is all this energy being transferred and why is it so cold in the middle of space?
Perhaps the transfer of heat is more complex than we think, as is the temperature itself.
Heat and Temperature
The universe is full of various stars, each of them is like a huge heat generator, transmitting its own heat outward.
This heat is transferred to other celestial bodies, such as planets, asteroids and even icy-looking comets.
However, the star is unable to heat up the space between it and the planet, which is why.
What's going on with the -270°C temperature in space?
For example, when it comes to the hottest planet in our solar system, Mercury is the first planet that comes to mind because it is the closest to the Sun.
However, according to the detection of Mercury, the side of Mercury facing the Sun is indeed very hot, able to reach a staggering 428 degrees Celsius.
Yet the side with its back to the sun can be as cold as minus 190 degrees Celsius, colder than even the coldest places on Earth.
Why is it that Mercury, the closest planet to the Sun, has such a huge temperature difference?
This brings us to the transfer of heat and the performance of temperature. There are three ways of heat transfer, the most common being heat conduction, such as people frying and cooking, gaining heat through direct contact with the heat source.
The second type is thermal convection, which occurs mainly on fluids, such as what we often hear about Siberian cold air, subtropical high pressure, Peruvian cold current, Gulf of Mexico warm current, etc.
The third mode of heat transfer is thermal radiation, which does not require a medium and is a common mode of heat transfer in the universe.
So how is the temperature of an object expressed? The answer is the motion of particles within matter.
The more intense the movement, the higher the temperature of this object will be.
Any object, is composed of a variety of particles, only the degree of movement of the various particles are not the same.
If two objects receive the same amount of heat, the one with the more intense thermal movement, the higher the temperature.
Different substances in the same place on Earth will have different temperatures, such as the temperature over the equator and the temperature at the surface of the equator.
This is because the temperature of the ground is generated by the internal movement of soil and rock particles after they receive the radiant heat energy from the sun.
The temperature, on the other hand, is the movement of the various gas molecules in the atmosphere in response to the heat of solar radiation, which is equivalent to the internal energy of the atmosphere.
From this we see that as long as the particles inside are in motion, then matter will have a temperature. The space environment is a vacuum, and heat can be transferred in it, but it does not exhibit temperature.
This is why there are so many stars in the universe, some of them are still giants, but it is impossible to heat the vacuum anyway.
The hot sun and the cold space
Why is the sun so hot? It is because the sun is a cosmic nuclear power plant.
The sun is composed of trillions of trillion tons of hydrogen atoms that are involved in fusion reactions that release enormous amounts of energy, the vast majority of which is heat.
The heat of the sun is transferred to the various celestial bodies in the form of thermal radiation and therefore does not require a medium.
Space environment is a vacuum, it will not have particles to receive the heat of the sun, there will be more particle motion, compared to other celestial bodies, the space environment is too cold.
It is reasonable to say that there is no particle movement, the temperature at this moment should be absolute zero - 273 ℃, why the temperature between the sun and the earth is - 270 ℃, the extra 3 ℃ when where to come from?
The space environment between the Sun and the Earth is a vacuum, and this vacuum does not mean that nothing exists, "everything is empty", but is relative to the standard atmospheric pressure of the Earth.
There are small amounts of dust in space that somehow gain some energy from the sun.
Only the density of this dust in space is too small compared to the celestial bodies, so only a temperature of 3°C is generated.
The dust comes from various impacts over the 4.6 billion years of the solar system, and some of the dust is even left over from the original nebula as "meta".
Absolute zero a physical concept, but only exists in theoretical values, the reality of the universe is not found.
The heat radiation from the sun has another characteristic, it travels along a straight line and does not turn.
If it is blocked by other objects in space, then it basically receives no heat from the sun.
For example, a human satellite, when it is facing the sun, must endure the heat coming from the sun directly, when the surface of the satellite can reach 200 ℃.
When the satellite orbits to the back of the Earth, at this time it is completely invisible to the sun, and does not receive the sun's heat, in the cold space environment, to endure the cold of minus 270 ℃.
Such "ice and fire" will make the satellite material to produce extreme thermal expansion and contraction, if the use of ordinary materials on Earth is completely impossible.
So the artificial satellite material must be able to withstand both the heat and the cold, both inside and outside.
The closest existence to absolute zero
Astronomers once suspected that absolute zero existed on Pluto because it was so far from the sun, which was once thought to be the coldest place in the solar system.
It turns out that the temperature of Pluto is still some way from absolute zero.
Although Pluto is far from the sun, it is still in the energy system of the solar system, then it will receive the heat of the sun anyway.
As long as it receives heat, then the particles inside Pluto will produce motion, only this motion is not as violent as the eight planets.
As the human-launched probe successfully reached Pluto and began its exploration, the surface temperature of Pluto was measured to be 229°C below zero, a temperature apparently much higher than absolute zero.
It was only later that astronomers discovered that the existence of a true proximity to absolute zero did not care about its distance from the Sun, but rather whether it was essentially particle motion.
It was at this time that astronomers discovered that the vacuum of space in the universe, other than the terrestrial body, was at a temperature of minus 270°C, which is the closest thing to absolute zero that exists.
We believe that the empty cosmic matter also exists invisible to humans, as long as there is matter, then it will have internal energy, no matter how low the temperature is, it can not be lower than absolute zero.
So, if there is some space in the universe that is really empty, not even dust, then would it be absolute zero?
The answer may also be no, because there is dark matter.
Dark Matter and Space Temperature
Dark matter is considered to be matter that is invisible to humans but real in the universe, and it is different from all the matter that makes up the celestial bodies.
Dark matter is the main part that makes up the universe, occupying 85% to 90% of the universe.
Astronomers believe that dark matter is involved in interactions in the universe and so there is mass.
It is a particle, but different from all the particles we know, which suggests that there are unknown particles in the universe that we think of as a vacuum.
Perhaps that 3°C above absolute zero may not be the solo of dust, but more like the whisper of dark matter.
If the existence of dark matter can be confirmed in the future, then absolute zero might really be just a theory, and it really does not exist in the universe.
Humans have attempted to create absolute zero, creating an ultra-low temperature of 0.00002K in 1957, which is the closest thing to absolute zero that currently exists.
Absolute zero is a temperature value that can only be reached infinitely but cannot be reached.
The heat transfer and temperature that seems so simple to us on Earth is so complex in the universe, and even full of various mysteries.
When you think about it, human beings are also part of the universe, although small as dust, but we ourselves are also composed of various particles, our body temperature remains at about 36 ℃, but also the result of thermal movement.
Look at it this way, we humans are mysterious too.
The universe is like this, from the Big Bang of 10 billion degrees Celsius to approach absolute zero, the temperature span is very huge, but also makes it full of all kinds of dangers.
When humans walk in space, it is the real dance between ice and fire, with the scorching heat of the sun on one side and the cold of space on the other.