The Sun is about 91% hydrogen, 8.9% helium, and 0.1% other elements. In the center of the Sun, nuclear fusion occurs, which releases a great deal of energy in the form of light and heat. Astronomers believe the interior of the Sun is about 15,000,000 °C (27,000,000 °F) at its core. The temperature at the Sun’s surface is about 6,000 °C.

Nuclear fusion is a process where atoms of hydrogen come together (or fuse) to form helium-4:

1. Two hydrogen nuclei fuse to form a deuterium nucleus.
2. The deuterium nucleus goes on to fuse with another hydrogen nucleus to form helium-3.
3. Two helium-3 nuclei fuse and form helium-4 and two hydrogen nuclei.

With each step, large amounts of energy in the form of heat and electromagnetic radiation are produced. Notice in this process, four hydrogen atoms are used, but only two are produced at the end. Eventually, the Sun will use up all its hydrogen. No need to worry, though—scientists estimate this will not happen for another 5 billion years!

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Question

What is the most common element in the Sun?

Answer

Hydrogen makes up 91% of the Sun.