The wavelengths of the visible light are from 400 nm for violet to 800 nm for the red. Our atmosphere is transparent to radio waves between 1 to 100 meter, visible light and a little bit of ultraviolet and infrared near the visible light. To observe all other waves from outer space, the telescopes have to be above the atmosphere in satellites. The atom is composed of protons, neutrons and electrons. The chemical characteristics of an atom depend on the number of protons and electrons.
Ordinary atoms are in neutral charge, that means the number of protons and electrons are equal.
The electrons occupy discreet energy levels inside the atom. In the past it was thought that the electrons had specific radii of orbits, but that is not the case. When an electron jumps from one discreet energy state to a lower energy state, the difference in energy is emitted as a photon. These various discreet photon energies are called emission spectra. Each type of atom has its own energy levels, and so the emission spectra are unique to each atom.