The sun is made mainly of hydrogen, and its energy comes from the nuclear fusion reaction by which hydrogen is converted into helium. The sun's "photosphere" -its visible, glowing surface-has a temperature approaching 6000oC, and is too bright to stare at directly with the naked eye. But the sun's core is far hotter still, at 15 million degrees.
太陽是一團以氫氣為主的「火球」，能量來自氫的核融合反應，肉眼可見的光球層，有六千度高溫，核心熱度更突破一千五百萬度，令人無法逼視。