What is the Sun Made Of?
Written by Fraser Cain
Interior of the Sun. Image credit: NASA
You know the Sun, it's that big ball of burning fire in the sky. Okay, that's not exactly the best scientific explanation. So what is the Sun made of?
If you could take the Sun apart, and stack up its various elements, you would find that the Sun is made of hydrogen (74%) and helium (about 24%). Astronomers consider anything heavier than helium to be a metal. The remaining amount of the Sun is made of iron, nickel, oxygen, silicon, sulfur, magnesium, carbon, neon, calcium and chromium. In fact, the Sun is 1% oxygen; and everything else comes out of that last 1%.
Where did these elements come from? The hydrogen and helium came from the Big Bang. In the early moments of the Universe, the first element, hydrogen, formed from the soup of elementary particles. The pressure and temperatures were still so intense that the entire Universe had the same conditions as the core of a star. Hydrogen was fused into helium until the Universe cooled down enough that this reaction couldn't happen any more. The ratios of hydrogen and helium that we see in the Universe today were created in those first few moments after the Big Bang.
The other elements were created in other stars. Stars are constantly fusing hydrogen into helium in their cores. Once the hydrogen in the core runs out, they switch to fusing heavier and heavier elements, like helium, lithium, oxygen. Most of the heavier metals we see in the Sun were formed in other stars at the end of their lives.
The heaviest elements, like gold and uranium, were formed when stars many times more massive that our Sun detonated in supernova explosions. In a fraction of a second, as a black hole was forming, elements were crushed together in the intense heat and pressure to form the heaviest elements. The explosion scattered these elements across the region, where they could contribute to the formation of new stars.
Our Sun is made up of elements left over from the Big Bang, elements formed from dying stars, and elements created in supernovae. That's pretty amazing.
Here's an article from Universe Today about the early formation of the Sun, and here's another article about the future of the Sun.
Here's a handy table showing the exact composition of the Sun, and a cool video from NASA answering the question.
We have recorded an episode of Astronomy Cast just about the Sun called The Sun, Spots and All.
Filed under: Astronomy
