Astronomy Practice Exam 2025 – Complete Preparation Guide

Nuclear fusion is the process where two light atomic nuclei combine to form a heavier nucleus, resulting in the release of a significant amount of energy. This energy release is primarily due to the conversion of some of the mass of the nuclei into energy, according to Einstein's famous equation, E=mc². In stars, including our Sun, this fusion process mainly involves hydrogen nuclei coming together to form helium, which generates remarkable amounts of energy, enabling stars to shine and produce light and heat.

While light energy is a byproduct of the fusion process, the key takeaway is that the primary energy release is indeed enormous, allowing for the conditions necessary for stellar and planetary systems to develop. Chemical energy, on the other hand, is related to the energies involved in the bonds between atoms in molecules, which is not the same as the nuclear processes occurring in fusion. Sound energy refers to the energy carried by sound waves, which is not relevant to the context of nuclear fusion. Hence, the production of extensive energy during fusion is what establishes its fundamental role in astrophysics and the functioning of stars.