[UCANSEE2]

Atomic spectroscopy measures transitions of the electrons between orbits in the atom, and does not depend on the details of structure of the proton.

More or less the same way they detect planets orbiting distant stars.

[dr_lew]

More or less the same way they detect planets orbiting distant stars.

I don't think you can say that. The electrons make quantum transitions between orbits, which is emphatically not the case for planets orbiting stars!