I'm surprised to read that "the scientific wisdom of the time (...) held that there were no significant elemental differences between the Sun and Earth", becaus

I'm surprised to read that "the scientific wisdom of the time (...) held that there were no significant elemental differences between the Sun and Earth", because I distinctly remember looking up why helium was named after Helios (the Greek name for the Sun). It turns out that it was discovered by analyzing the spectrum of the Sun, only years later being isolated from Earth minerals.