The spectrum of light from the Sun tells us what it is made of.
The less-dense gas in the layers of the Sun above the visible surface
(the photosphere) absorb light from the photosphere, giving
a dark line spectrum. This enables us to learn what at least the outer
layers of the Sun are made of.
The element helium was discovered this way.
A certain amount of detailed analysis is needed. Here is what is found.
For each element listed I show the approximate fraction of the mass
of the gas near the surface of the Sun that is made of that element.
- H (hydrogen) 0.735 ~ 0.75
- He (helium) 0.248 ~ 0.25
- Li (lithium) 1.55 x 10-9
- Be (beryllium) 1.41 x 10-11
- B (boron) 2.00 x 10-10
- C (carbon) 3.72 x 10-4
- N (nitrogen) 1.15 x 10-4
- O (oxygen) 6.76 x 10-4
- ...
Some comments:
- The sun is mostly hydrogen, about 25% helium.
- These are the two lightest elements.
- There is a small fraction of heavier elements.
- Hydrogen and helium are the most important in understanding stars.
- The heavier elements do play some role in stars.
- The heavier elements are important to us, since we are made of them.
- It appears that the heavier elements were made in stars!
Davison E. Soper, Institute of Theoretical Science,
University of Oregon, Eugene OR 97403 USA
soper@bovine.uoregon.edu