Space is an almost perfect vacuum. It has nearly no matter and very low pressure. Also, sound cannot travel in space because there are not enough molecules closely packed together to carry sound waves from one place to another. This makes us wonder whether space has air.
Yes, there is air in space as far as scientists have discovered. However, it is different from the air on Earth. Air combines gases comprising nitrogen, oxygen, and many others. At higher altitudes in the atmosphere, these air molecules start to decrease in number. Thus, air continues to become thinner as you go up.
At very high altitudes, only light gases such as helium and hydrogen remain in space. Air gets thinner because most of the air and heavier gases are held closer to the Earth’s surface. Earth’s strong gravitational force pulls them towards it. So, is space a perfect vacuum?
Is Space A Perfect Vacuum?
Space appears as a black hole with dotted stars. Although there is no air in space, it is not a perfect vacuum. This is because gas and dust particles are still floating around in space. Beyond Earth’s atmosphere is the Interstellar Medium. This medium fills the space in our universe around the stars and galaxies.
It is a common misconception that there is no matter in space. People believe so because there is less matter in space than in any vacuum artificially created on Earth. However, there is still some matter in space. Even the most vacant areas in space have about a few hundred molecule atoms every “cubic meter.”
The regions where some matter exists have extremely low densities. They mainly consist of gas, with hydrogen and nitrogen comprising most of it, and floating dust particles. Due to lower density, the matter gets spread out.
This interstellar dust is different dust particles found on Earth. These particles are tiny, weighing less than a fraction of a micron. Additionally, the dust particles do not have a consistent appearance. They comprise silicon, carbon, ice, and iron compounds.
Space also consists of many forms of radiation. Many of these infrared and ultraviolet radiations come from the sun and are dangerous to astronauts. Other rays arrive from distant star systems, including x-rays, gamma rays, and cosmic rays. These rays have intense energy and travel approximately at the speed of light.
Although space is not a perfect vacuum, does breathable oxygen exist in space?
If you’re interested in knowing more, take a look at this video about what would happen if the space vacuum was replaced with air:
Does Space Have Breathable Oxygen?
There are hardly any oxygen molecules in space. This is because, in space, oxygen atoms hold on tightly to the stardust, which prevents them from combining together to form oxygen molecules. When oxygen atoms cannot convert into oxygen molecules, breathable oxygen, O2, does not exist.
Oxygen is our universe’s third most common air element after hydrogen and helium. Thus, earlier astronomers predicted that molecular oxygen would be the third most common molecule in the interstellar medium after hydrogen and carbon monoxide. However, this is not the case.
Molecular oxygen has only been found in two places in space: the Orion Nebula and the Rho Ophiuchi cloud. Even here, oxygen molecules are scarce. In the Orion Nebula, there are more oxygen molecules than hydrogen molecules at a ratio of one to a million.
So, what happens to oxygen atoms in space?
What Happens To Oxygen In Space?
A recent scientific study stimulated space dust cloud and their conditions on Earth. The study found that the binding energy for oxygen atoms is twice as strong as previously thought.
This means that in the clouds of stardust in space, oxygen atoms cannot form molecular and breathable oxygen because they are not free. They are tightly combined with grains in the space dust. Thus, instead of joining with other oxygen atoms to form oxygen molecules, they combine with hydrogen to create water, which later freezes.
Therefore, although there are plenty of individual oxygen atoms around the stars in space, stardust gathers and firmly holds onto them. Now, let’s discuss the comparison between the Earth’s atmosphere and space.
How is Space Different From the Earth?
If we talk about the Earth, many molecules, atoms, and particles exist at a certain level, maintaining life and stability. Depending on the density of each molecule, Earth’s atmosphere comprises five main layers, shown in the table below.
| Layer | Distance From Earth’s Surface |
| Troposphere | 0km to 12km (0 to 7 miles) |
| Stratosphere | 12km to 50km (7 to 31 miles) |
| Mesosphere | 50km to 80km (31 to 50 miles) |
| Thermosphere | 80km to 700km (50 to 440 miles) |
| Exosphere | 700km to 10,000km (440 to 6,200 miles) |
The abovementioned layers exist because Earth’s gravitational pull attracts all molecules towards it. Molecules have the highest density in the innermost layer of the atmosphere because it is the closest to the Earth’s surface. Thus, gravity is most substantial in this layer.
As you go higher in the atmosphere, Earth’s gravitational pull and density of the air start to decrease. This results in very few air molecules in the Exosphere compared to the Thermosphere.
Therefore, as we continue to go to outer space, the effects of gravity become negligible. So, although some particles exist in space, they are insufficient to sustain living things. This also depends on whether we are talking about empty space in the cosmos or another planet’s atmosphere.
Each planet has its own gravity, depending on its mass. Thus, the greater a planet’s mass, its gravitational force will be greater. This means that air molecules will have a higher density as they come nearer a planet’s surface. For life to exist on these planets, the balance among air molecules must be like Earth’s.
Final Takeaway
In conclusion, air does exist in space but is different from air found on Earth. It contains a different composition of gases, with very little oxygen. Several reasons lead to this difference, including the lack of gravitational pull in space, oxygen atoms closely attached to stardust, and lower air density.
