Studies of the solar spectrum have determined the relative abundances of about 70 elements in the Sun's atmosphere. Hydrogen and helium predominate, and in general abundance decreases with increasing atomic number. A few exceptions, however, e.g. silicon and iron, have a high abundance, probably correlated with nuclear binding energies and nuclear stability. Spectra originate from the outer layers of the Sun, so their value in determining the total solar abundance of elements should not be over-emphasized, but total abundances of elements are much less important than their relative proportions.
Subjects: Earth Sciences and Geography.