In order to answer the question of why there is no air in space, you first need to determine what air is. So, air is nothing but molecules and particles floating in space. Details in the article.
Earth and its atmosphere
If we talk about our planet Earth, then there are a large number of molecules, atoms, particles that make up our atmosphere. In the air, there are about 78.09% nitrogen, 20.95% oxygen, 0.04% carbon dioxide, etc. by volume. Based on the density of molecules at different levels, scientists divide the atmosphere into five main layers:
- Troposphere: from 0 to 12 km above sea level.
- Stratosphere: 12 to 50 km.
- Mesosphere: from 50 to 80 km.
- Thermosphere: from 80 to 700 km.
- Exosphere: from 700 to 10,000 km.
These layers exist because the Earth's gravity attracts all the molecules. Actually, this fact explains why air does not fly into space with the atmosphere. The density of troposphere molecules is high, because it is the layer that is closest to the Earth's surface, which means that the influence of gravity on the molecules is very large. However, if we rise higher and higher and thus move away from the Earth’s surface, the effect of gravity will decrease with time, and with it the air density will decrease. Therefore, the exosphere layer has, in comparison with the troposphere layer, an extremely low percentage of the content of molecules.
Now we turn directly to the question of why there is no air in space. Actually, from the point of view of physics and astronomy, this question is not 100% correctly formulated. The fact is that air is present even in space. The only remark is that such air is not suitable for any living creatures. It is also worth clarifying that when we think about the question of why there is no air in space, do we mean the word "space" directly empty space or the atmosphere of other planets?
Is there really no air in space?
So, if we are talking about the atmosphere of other planets, it is worth noting that each planet has its own gravity. This gravity also depends on the mass of the planet, because it is nothing but a force that affects the degree of curvature of space-time. The greater the mass of the body (planet or star), the higher the degree of curvature. It also means that the greater the mass of the body, the stronger the gravity. On other planets, the ratio of the density of molecules in different layers of the atmosphere and the force of gravity is identical to the nature of the relationship of gravity and atmosphere on planet Earth.
So, the density of air molecules will be higher at the surface of the planet, and the density index will decrease when moving up. However, for the existence of living organisms on this planet, the composition of the air molecules must be balanced, similar to what on Earth.
But if we talk about the empty space of space, which we call the vacuum, it should also be said that in fact it is not a vacuum at all. Because even empty space is something. It also contains hydrogen molecules and some other particles. But the density of these molecules and particles is extremely insignificant, because the gravitational field of some celestial object does not exert a strong influence on them.
For this reason, we say that there is no air in space. But in reality this is not true. Nevertheless, some particles still exist in outer space.
Explanation for children: why there is no air in space
Imagine a large empty room (for example, the size of a city). Now imagine that you left an ant in it. The probability that you will be able to find him is equal to 1/1000000000. The Universe is the same room, and since the gas tends to occupy all the free space, its molecules move away from each other - their density is extremely low.
It’s like a drop of ink in the ocean - it is not visible, it does not affect anything. It is worth noting that, in fact, a certain percentage of air still leaves the Earth’s atmosphere, which, falling into the universe, does not have any significant effect on outer space.
Total
In general, space is so mysterious that scientists still have not figured out what properties it has. Physicists are sure that in outer space there are even some particles that we do not yet know about. So, since air is made up of particles, molecules, etc., it will be wrong if we say that there is no air in space. Instead, we should ask ourselves what particles are in space.