When we talk about the universe and the components that make it up, we usually talk about the cosmic radiation. It is a type of energy that travels through space. It is found in almost every corner of the universe and has a somewhat special composition.
In this article we are going to tell you what cosmic radiation is, its importance, composition and much more.
What is cosmic radiation
Cosmic radiation is a form of energy that travels through space from all directions in the universe. This radiation is composed of subatomic particles, mainly high-energy protons and electrons, moving at speeds close to the speed of light. These particles come from various cosmic sources, such as stars, supernova explosions, and black holes.
One of the most important sources of cosmic radiation is the Sun. The Sun emits charged particles, known as solar wind, which travel through space and reach Earth. However, cosmic radiation comes not only from the Sun, but also from other stars and distant celestial objects. These particles travel thousands of light years through space before reaching us.
As these high-energy particles collide with Earth's atmosphere, they interact with air molecules and create a cascade of secondary particles. These secondary particles are what eventually reach Earth's surface, where they can be detected by sensitive instruments. Cosmic radiation is a natural part of the space and Earth environment, and in small amounts, does not present a significant risk to humans. However, in certain scenarios, such as prolonged spaceflight or exposure at high altitudes, astronauts and airplane passengers may be exposed to higher levels of radiation than at Earth's surface. For this reason, radiation is monitored and considered in space mission planning and by the aviation industry.
Composition:
Cosmic radiation consists of energetic ionized atomic nuclei that travel through space at a speed very close to the speed of light (approximately 300.000 km/s). The fact that they are ionized suggests that they have acquired an electrical charge as a result of being deprived of electrons, but oddly enough, these nuclei are made of the same material that makes us and everything around us.
The nuclei that make up cosmic rays are distributed in a different way than the matter that gives us shape. Hydrogen and helium are much more abundant in the solar system than in cosmic rays, and other heavier elements, such as lithium, beryllium or boron, they are 10.000 times more abundant in cosmic radiation. This variation in composition makes studying cosmic radiation and its characteristics essential to better understanding the universe around us. To learn more about radiation's connection to the cosmos, you can consult This article about the cosmic web.
One of the most important characteristics of cosmic radiation is its essentially perfect isotropy. This parameter reflects that lightning strikes with the same frequency from all directions, which means that the multitude of sources capable of producing them must coexist at the same time.
Origin of cosmic radiation
Cosmic rays were not a direct consequence of the Big Bang. During the first phase of the formation of the universe, which began about 13.800 billion years ago, few atomic nuclei heavier than hydrogen and helium were produced. They are the most abundant, accompanied by only small amounts of lithium and beryllium, a distribution that, as we have seen, does not coincide with that of the atomic nuclei that make up cosmic rays.
A significant part of the radiation that penetrates the Earth's atmosphere comes from the Sun, which is known to be the closest star. However, it is by no means the only source of external radiation reaching Earth. Most of the cosmic rays we receive come from outside our solar system from other stars. They travel through space with enormous energy until they collide with atoms in the upper layers of Earth's atmosphere.
The chemical elements that make up ordinary matter and ourselves are synthesized in the cores of stars. If you want to know exactly how this process works, you can check out our dedicated article, but for now, just remember that about 70% of their mass is hydrogen. 24% to 26% helium, and 4% to 6% is a combination of chemical elements heavier than helium. This information is essential to understanding the composition of the nuclei that form cosmic radiation.
The cloud of dust and gas that forms a star through gravitational contraction increases in temperature until the nuclear furnace ignites and the first fusion reactions begin in its core. This process allows the star to release energy and produce elements heavier than hydrogen and helium. As the star runs out of fuel, it readjusts to maintain hydrostatic equilibrium.
This property keeps the star stable for most of its active life, as gravitational contraction "pulls" the star's material inward, balanced by gas pressure and radiation emitted by the star. The stars "pull" matter although their fuel is not eternal. This stellar dynamic is what ultimately gives rise to the cosmic radiation that affects us.
the earth protects us
Our planet has two very valuable shields that protect us from solar radiation and cosmic radiation beyond the limits of our solar system: the atmosphere and the Earth's magnetic field. The latter extends from the Earth's core beyond the ionosphere, forming a region known as the magnetosphere, capable of deflecting charged particles towards the Earth's magnetic poles. This mechanism protects us to a great extent from the solar wind and cosmic rays.
However, that doesn't prevent some high-energy nuclei from colliding with molecules in the outermost layers of the atmosphere, creating showers of less dangerous, lower-energy particles that occasionally reach the Earth's crust. This is why the atmosphere also plays a very important protective role, as you can read in our article on the layers and functions of the atmosphere.
I hope that with this information you can learn more about what cosmic radiation is, its origin and much more.
