The Sun is the energy source of our universe. It provides the heat and light that allows life on Earth to survive. It is a molten hot ball that is many times more massive than the Earth. It is very interesting to think about how the Sun produces such high amounts of energy. The Sun (and other stars) produce their energy through the process of nuclear fusion. In stars the size of our sun, hydrogen atoms are turned into helium atoms through nuclear fusion. Some of the matter is not converted into helium and is instead turned into photons which radiate from the sun and provide heat and light to the planets in our solar system. When this light travels through the solar system and reaches Earth, the light is filtered through the ozone layer in the atmosphere which removes harmful ultraviolet radiation. In one second, the Sun fuses about 620 million metric tons of hydrogen in its core. The main difference between the sun and other much larger stars are the elements that they fuse. When larger stars fuse heavier elements there is more energy that is released which generates more heat and pressure.