The Sun is made up of 70% hydrogen (H) and 28% helium (He) atoms.1 Other substances make up less than 2%. Six hundred million tons of hydrogen are converted into 596 million tons of helium in the Sun every second. The remaining 4 million tons is given off as heat and light energy. In that sense, the first thing that comes to mind when the Sun is mentioned is the letters H (hydrogen) and He (helium) that stand for the Sun. Read more