متن اصلی - انگلیسی - How can we know stellar ages when, • except for...

How can we know stellar ages when, except for catastrophe, we hardly ever see the stars change? We cannot actually watch a star be born, go through its youth and middle age, and finally die. We have to catch individuals along the way and string them together with the aid of logic and theory and the fundamental reference, the Sun and its family.