Metallicity Classification in Astronomy

The chapter explores the classification of elements in the universe, focusing on the term 'metal' utilized by astronomers to describe elements beyond hydrogen and helium. It emphasizes how 'metals' in astronomy encompass all elements except hydrogen and helium, constituting the majority of the universe. The discussion deepens into the analysis of stars' metal content, the Sun's fusion process involving hydrogen, and the methods to determine the Sun's interior composition through helioseismology and sound wave observations.