The Sun generates energy by fusing hydrogen into helium due to a process known as nuclear fusion. Fusion occurs within the Sun because the plasma in the solar core is full of hot gases that collide with one another at extremely high speeds. In most cases, electromagnetic repulsion forces deflect the nuclei of the two atoms preventing collisions, however, if the nuclei collide with sufficient energy, they can fuse together to form a heavier nucleus. A force known as the strong force binds protons and neutrons together in atomic nuclei, is the only natural force that can overcome the electromagnetic repulsion between two positively charged particles. In order for nuclear fusion to occur, the two charged nuclei must be pushed close enough together for the strong force to overpower electromagnetic repulsion.
The high temperatures and pressures in the Sun’s core are what allow nuclear fusion to occur. High temperatures provide atoms with more energy which in turn causes atoms to move faster therefore increasing the probability of collisions occurring. The high pressure on the Sun’s core is important for nuclear fusion because without it the solar core would explode into space, therefore halting all nuclear reactions.
The overall reaction of nuclear fusion proceeds through several steps known formally as the proton-proton chain. This chain of reactions begins with two protons fusing to form a deuterium nucleus consisting of one proton and one neutron. The deuterium nucleus then fuses with a proton to produce a helium-3 nucleus made of two protons and one neutron. Finally, two helium-3 nucleus combine to form a helium-4 nucleus consisting of two protons and two neutrons, releasing energy in the process. This energy produced from nuclear fusion provides the energy necessary for live to thrive on Earth. If the Sun were to suddenly halt all nuclear fusion this would be detrimental for all living organisms on Earth. There is a reality to this statement, though: the Sun will eventually run out of fuel to perform nuclear fusion and then it will die. Our Sun is currently halfway through its fuel reserves, so in 7.5 billion years our ancestors will have to come up with another way to provide energy for Earth, or they will have to move to a another solar system. Yikes! Thank goodness this will not happen any time close to my lifetime so I will not have to deal with this problem.