How do scientists know what the sun is made of in the atmosphere?

Scientists determine the composition of the Sun's atmosphere primarily through spectroscopy. By analyzing the light emitted by the Sun, they can identify specific wavelengths that correspond to different elements and compounds. When sunlight passes through the Sun's atmosphere, certain wavelengths are absorbed by elements like hydrogen, helium, and heavier elements, creating absorption lines in the spectrum. Comparing these lines to known spectra of elements allows scientists to infer the Sun's atmospheric makeup.