Scientists puzzled over how nuclear fusion occurred in the sun for a long time. Thanks to twentieth-century research, we have an answer.
In 1920, Arthur Eddington, a British astrophysicist, proposed the theory of the sun’s fusion. This groundbreaking idea suggested that hydrogen fusion into helium gives stars their seemingly limitless energy.
Another theoretical physicist Hans Bethe confirmed the postulation in 1939 with his “proton-proton chain.”
Nearly 100 years later, scientists were finally able to test this theory by observing the sun’s gamma-ray burst. These bursts were used to measure the universe’s expansion and confirm previous theories.
We will be looking at the sun, its fusion process, and its different zones. Stay tuned for more.
Where Does Nuclear Fusion Occur In The Sun?
The core. The sun’s core is where nuclear fusion occurs. The temperature in the core is about 15 million degrees Celcius, and the pressure is about 250 billion times atmospheric. In the core, the hydrogen atoms fuse to create helium atoms.
The temperature and pressure are so high that the nuclei can overcome their natural repulsion and fuse together.
What Is The Sun Made Of?
The sun is a fantastic object in our solar system. It’s enormous, and its gravity affects everything in our system. But what is the sun made of?
The sun is made of gas and plasma, with gas mostly hydrogen and helium, while the plasma is made of other elements.
The sun’s photosphere temperature is about 5504 degrees Celsius, and it’s about 150,000km away from Earth.
What Is Nuclear Fusion?
When two or more atomic nuclei collide together to form a single, heavier nucleus, the process is known as nuclear fusion. The process releases a tremendous amount of energy.
How Does Nuclear Fusion Occur In The Sun?
Nuclear fusion is the process that powers the sun. Two atoms of hydrogen (light elements) fuse to become one atom of helium (a heavier element).
In other words, the sun is powered by the fusion of hydrogen atoms. In the sun’s core, the temperature is so high(15million degrees Celcius, can you imagine that!) that the atoms are stripped of their electrons. These free protons then collide and fuse to form a helium atom.
The process repeatedly happens, which generates the sun’s enormous energy. Scientists think that this process occurs in other stars too.
The process of nuclear fusion is not entirely understood. Still, scientists have been able to replicate it in a lab setting (one such example is at a facility in Culham, near Oxford, United Kingdom).
Fusion reactors are currently under development, and scientists hope that they will one day provide a clean and renewable energy source.
The sun’s fusion rate is in equilibrium. So, what does this mean? The sun’s energy loss rate determines the sun’s fusion rate.
In other words, the energy released by the fusion of hydrogen atoms into helium atoms is equal to the energy used to force those atoms together. This balance is maintained by the pressure of the radiation from the sun’s surface.
If the fusion rate increased, the core would grow in size. The increased gravity would then cause more fusion to take place, which would, in turn, increase the pressure, and the balance would be restored.
On the other hand, if the fusion rate decreased, the pressure would decrease and restore the equilibrium; this equilibrium results from the sun’s thermonuclear reactions.
What Are The Different Zones Of The Sun?
The sun has several regions, each of which has unique characteristics.
The Core
The core of the sun is the hottest and most active region. And we’ve established that this is where nuclear fusion occurs. The core is the layer of the sun that is responsible for energy production.
The main component of this zone is hydrogen gas. When hydrogen atoms collide, they fuse to create helium atoms. This process releases energy, which travels outward from the core to the sun’s surface.
Radiative zone
The core is surrounded by the radiative zone, home to the sun’s energy-transferring plasma. The radiative zone is the layer of the sun that is sandwiched between the convective zone and the core. In this layer, energy is transported from the core to the sun’s surface.
The photons released by the atoms in this zone are responsible for transporting the energy to the sun’s surface.
The temperature in the radiative zone drops from 7 million to 2 million kelvins. Therefore energy transfer is through radiation and not thermal convection.
Tachocline
The tachocline is a transition layer from radiative to convective zones.
Convective zone
The convective zone surrounds the radiative zone and is where the sun’s gas is in constant motion; this is the layer of the sun where energy is transported to the surface by convection.
This layer is located just below the photosphere and has a temperature of about 6,000 Kelvin(5,700 K, to be exact). Energy is transported upward by the movement of hot gas, which rises because it is less dense than the colder gas around it.
The Photosphere
The photosphere is the layer that we see when we look at the sun and is the source of most sun’s light. It’s the layer we see as the bright disk in the sky.
It’s a thin, gaseous layer made up of gas particles that are very hot and dense that makes up the sun’s surface.
The photosphere is about 300 kilometers thick and has a temperature of about 5,800 Kelvin(5504℃). The temperature of the photosphere decreases with increasing altitude.
The Atmosphere
The sun’s atmosphere is a layer of gas that surrounds the sun. The atmosphere is made up of plasma, a hot gas made of free electrons and ions.
The sun’s atmosphere divides into four parts: the chromosphere, transition region, corona, and heliosphere. These regions are hotter than the sun’s surface, and no one knows why.
The chromosphere
The chromosphere is the layer of the sun’s atmosphere just above the photosphere. It is responsible for the reddish hue of the sun’s surface; you’ll see it as a pink or red hue in photos of the sun taken with optical filters.
The chromosphere is roughly 2,000 kilometers deep and has a temperature of about 20,000 K.
The transition layer
This layer spans around 200m thick, and temperatures rise rapidly from 20,000K to about 1million K.
Corona
The corona is where the solar wind originates. It is a region of plasma that is constantly in motion and is much hotter than the sun’s surface. The corona is visible during a solar eclipse when the moon blocks the sun’s bright disc.
Surprisingly, the temperatures here are between 1million-2milion Kelvins, with the hottest region being 8million-20million Kelvins.
No theory is yet to explain the tremendously high temperatures, although some can be attributed to magnetic reconnection.
The Heliosphere
The heliosphere is the gigantic, magnetic bubble that surrounds the sun and most of the solar system.
It’s made up of the sun’s magnetic field and the solar wind- a stream of charged particles that flow out from the sun. The heliosphere protects us from cosmic radiation and interstellar gas.
What We’ve Learned From Nuclear Fusion Of The Sun
- Nuclear fusion of the sun is a process that has been happening for billions of years. The sun’s core is heated to millions of degrees in this process.
The hydrogen atoms fuse to create helium atoms; this generates vast amounts of energy released into the sun’s atmosphere.
- Scientists have developed technology that can replicate this process here on Earth; this could provide a virtually limitless source of energy for our planet. Nuclear fusion reactors on Earth work in a very similar way to the sun’s core.
- The sun is about halfway through its life (at 4.5 billion years); it will live for about 5 billion more years before becoming a Red Giant. It means that it will be bigger and colder at the same time and 2000 times brighter!
- The sun is made of gas, mainly hydrogen, which makes up about 74%.
- The sun is so big that 1.3 million Earths could fit inside it!
- The sun is so hot that the gas atoms are ionized, meaning that the electrons have been stripped from the atoms.
- The sun does not have a definite boundary; rather, its density decreases exponentially.
Conclusion
It took hundreds of years, but scientists finally solved the mystery of where nuclear fusion occurs in the sun. It’s now known that it takes place in the sun’s core, rather than at its surface as was long believed.
This knowledge is essential for our understanding of how our sun works and future efforts to create nuclear fusion as a source of sustainable energy. The findings could also help us better understand how the sun works and improve our predictions of solar activity. We hope this read has been enlightening.
