The fire or flames we typically associate with combustion on Earth do not occur on the Sun. The Sun generates its energy through a process called nuclear fusion, specifically a type known as thermonuclear fusion.
In the core of the Sun, where temperatures and pressures are extremely high, hydrogen nuclei (protons) collide and fuse together to form helium nuclei. This fusion process releases an enormous amount of energy in the form of light and heat. The energy is generated through a series of nuclear reactions called the proton-proton chain.
Here's a simplified version of the proton-proton chain:
- Two protons (hydrogen nuclei) combine to form a deuterium nucleus (one proton and one neutron), releasing a positron and a neutrino.
- The deuterium nucleus combines with another proton to form a helium-3 nucleus (two protons and one neutron), releasing a gamma ray.
- Two helium-3 nuclei combine to form a helium-4 nucleus (two protons and two neutrons). Two protons are released in this process.
- The released protons can then go on to participate in further fusion reactions.
This ongoing fusion process in the core of the Sun generates an immense amount of energy, primarily in the form of high-energy photons (gamma rays) that are gradually converted to visible light as they travel outwards from the core. This energy release is what provides the Sun with its heat and light, sustaining life on Earth and powering various solar phenomena.