What Is the Element Composition of the Sun?

What Is the Sun Made Of? - Solar Chemistry

The sun consists mostly of hydrogen and helium.
The sun consists mostly of hydrogen and helium. SCIEPRO/ Brand X Pictures/ Getty Images

You may know the sun consists mainly of hydrogen and helium. Have you ever wondered what about the other elements in the sun? About 67 chemical elements have been detected in the sun. I'm sure you're not surprised that hydrogen is the most abundant element, accounting for over 90% of the atoms and over 70% of solar mass. The next most abundant element is helium, which accounts for almost just under 9% of the atoms and about 27% of the mass.

There are only trace amounts of other elements, including oxygen, carbon, nitrogen, silicon, magnesium, neon, iron, and sulfur. These trace elements make up less than 0.1 percent of the mass of the sun.

The sun is constantly fusing hydrogen into helium, but don't expect the ratio of hydrogen to helium to change anytime soon. The sun is 4.5 billion years old and has converted about half of the hydrogen in its core into helium. It still has about 5 billion years before the hydrogen runs out. Meanwhile, elements heavier than helium form in the sun's core. They form in the convection zone, which is the outermost layer of the solar interior. Temperatures in this region are cool enough that the atoms have enough energy to hold their electrons. This makes the convection zone darker or more opaque, trapping heat and causing the plasma appear to boil from convection. The motion carries heat to the bottom layer of the solar atmosphere, the photosphere.

Energy in the photosphere is released as light, which travels through the solar atmosphere (the chromosphere and corona) and passes into space. Light reaches the Earth about 8 minutes after it leaves the sun.

Here is a table listing the sun's elemental composition, which we know from analysis of its spectral signature.

Although the spectrum we can analyze comes from the solar photosphere and chromosphere, scientists believe it is representative of the whole sun, except for the solar core.

Elemental Composition of the Sun

Element% of total atoms% of total mass

Source: NASA - Goddard Space Flight Center

If you consult other sources, you'll see the percentage values vary by up to 2% for hydrogen and helium. We can't visit the sun to sample it directly, and even if we could, scientists would still need to estimate the concentration of elements in other portions of the star. These values are estimates based on the relative intensity of spectral lines.