When it comes to space, the imagination takes flight like a comet. If you have ever given yourself the opportunity to leave all the duties of daily life to lose yourself in astronomical observation, hundreds of questions may have come to mind about how things work out there. What would it be like to live without gravity? What would happen if an astronaut got lost in space? How does time pass out there? More and more questions suddenly appear and perhaps among so many, have you ever wondered why the temperature of space is so cold if the Sun is so hot? An excellent question.
First you have to think that the Universe is much larger than our Solar System. Although we like to be the protagonists, the truth is that in the immensity of the cosmos we are practically a point in nothingness. Thus, in the midst of all this immensity, extremely extreme temperatures can be found. Our Sun, for example, is a ball of burning gas that in its hottest part reaches 15 million °C, according to NASA. However, space temperatures are oppositely different from this data. The temperature of space at the cosmic background reaches -270°C.
So how is space freezing if the Sun is burning? To answer this question, you must first understand how heat spreads. In space, heat from the Sun and other stars that are burning at millions of °C, travels in the form of radiation, which is a wave of infrared energy. On Earth, radiation waves come into contact with molecules, causing them to heat up. However, in space the scenario is totally different.
How does heat spread on Earth?
Our planet is very special, it has a protective bubble that works as the shield of life. Thanks to the composition of the , the air remains warm even if we are in the shade. Why does this happen? This is because there are three different ways that heat travels through our biological bubble: conduction, convection and radiation.
Thus, when radiation waves from the Sun come into contact with air molecules, they become excited and with rapid movement, they heat up. They then transfer this energy to the surrounding molecules, triggering a chain reaction. This way of heat transfer is called conduction and it is the reason why you feel heat even in spaces outside the path of the Sun.
A cold void
Returning to space, it is practically empty and its temperature is too cold due to the enormous distances between each cosmic body. Furthermore, there is no atmosphere like there is on Earth. There are no sets of gas molecules, in fact, they are quite rare. Therefore, there is no opportunity for heat conduction, since they are far enough away that they cannot transfer their heat, even though they are within paths of solar radioactive waves.
The other way of heat transfer on Earth apart from radiation and conduction is convection. But for it to occur, a hydrological cycle is required, a cycle that does not exist in space. In addition, it also depends on the gravity and precipitation of droplets that are condensed by the heat absorbed by the water on the Earth’s surface through convection.
In other words, the Earth is wonderful and carries out endless processes to keep us alive. Processes that certainly do not occur in the vacuum of space, although we are not sure that they do not occur in others in the Universe, the eternal question.