On Earth, nuclear power plants use fission to generate electricity. In fission, a heavy element like uranium is broken into many atoms, where the total mass of the fragments is less than the original atom. Explain why fission could not be powering the Sun today.

Nuclear fusion is a process where two light atomic nuclei combine to form a heavier nucleus. This happens under extreme temperature and pressure conditions. The primary fuel for fusion is hydrogen, and the result is a new element, typically helium.
During fusion, a significant amount of energy is released because the mass of the new nucleus is slightly less than the sum of the original nuclei. This 'missing' mass is converted into energy according to Einstein's equation. Fusion is the dominant energy source in stars, including our Sun.
Compared to nuclear fission, fusion produces less harmful radiation and more energy per unit mass.

Nuclear fission is the process where a heavy atomic nucleus, like uranium-235 or plutonium-239, splits into smaller nuclei, along with a few neutrons and a large amount of energy. This process can be initiated by the nucleus absorbing a neutron.
Fission releases energy because the total mass of the resulting particles is less than the original mass. The 'lost' mass is converted to energy via Einstein's equation, \( E = mc^2 \). Unlike fusion, fission is used in nuclear power plants on Earth to generate electricity.
One drawback of nuclear fission is that it produces radioactive byproducts, which can be hazardous and need careful disposal. Additionally, the process can be fast and uncontrolled, leading to potential risks like nuclear meltdowns.

The primary energy source of the Sun is nuclear fusion. In the Sun’s core, hydrogen nuclei (protons) fuse to form helium in a series of reactions known as the proton-proton chain. This process releases a tremendous amount of energy, which we perceive as sunlight and heat.
The extreme temperature and pressure in the Sun's core, about 15 million degrees Celsius, provide the necessary conditions for fusion. This ongoing fusion process has kept the Sun shining for roughly 4.6 billion years and will continue for billions more.
Fusion in the Sun not only produces energy but also generates neutrinos and other subatomic particles, contributing to our understanding of particle physics and astrophysics.

Einstein's famous equation, \( E = mc^2 \), explains the relationship between mass (m) and energy (E), with c representing the speed of light in a vacuum. This equation shows that mass can be converted into energy, which is essential in both nuclear fission and fusion.
In nuclear fusion, a fraction of the mass of the hydrogen nuclei is converted into energy when they fuse to form helium. Similarly, in nuclear fission, the mass of the composition’s fragments is less than the original heavy nucleus, with the mass difference converted into energy.
This principle is fundamental in explaining why so much energy is released in nuclear reactions and helps us understand the underlying processes powering stars and nuclear reactors.

Hydrogen fusion is at the heart of the energy production in stars, including the Sun. This process involves the fusion of hydrogen nuclei (protons) into helium. In stars like the Sun, this occurs mainly through the proton-proton chain reaction.
The fusion process begins when two protons collide and merge to form a heavier nucleus. Due to the extreme conditions in the Sun, these reactions happen continuously and release enormous energy.
Hydrogen fusion is much more efficient than nuclear fission and ensures the longevity and stability of stars. This process also has the advantage of producing relatively low amounts of radioactive waste compared to fission.
Understanding hydrogen fusion has significant implications for developing clean and almost limitless energy sources on Earth in the future, through potential technologies like fusion power plants.