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Bernardo de La Paz

(59,743 posts)
5. The only stupid questions are the ones not asked or ones asked as something other than questions.
Tue Oct 21, 2025, 10:26 PM
Tuesday

You are not asking stupid questions.

Yes, the compounds could be detected by very careful fine grain analysis of multiple colour filtered images in principle. I'm not sure if images are the actual way, or if there is other multi-band spectral analysis of finer grained samples.

Different compounds glow at different colours dominated by spectral lines. Those are bright lines that are specific to certain electron orbital shifts. When an atom gets heated, its electrons get excited and shift to more energetic orbits. Then they re-emit some of that energy as they fall to lower energy orbits, energy mostly as photons of certain wavelengths (colours) depending on the exact orbitals.

Hydrogen for example has a very bright line. "21 cm" is what my faulty memory suggests, or maybe that might be a wavelength with very little emission from any element (specifics could be looked up but are not key to the principle of the emissions).

Dust clouds and outer layers of stars "atmospheres" can show as dark lines (absorption spectra).

It has to be all very carefully calibrated and analyzed, but that is what is what astronomers do.

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