The gas that makes up the majority of the sun is hydrogen, accounting for approximately 74% of its mass. Helium is the second most abundant element, comprising about 24% of the sun's mass. The sun generates energy through nuclear fusion, a process that occurs in its core where hydrogen atoms merge to form helium, releasing immense amounts of energy in the form of light and heat. This energy is essential for sustaining life on Earth and drives weather patterns and ocean currents within our planet's atmosphere.