The orange light is very likely sodium D lines.
Sodium is present in glass, and emits light when excited. Electrons are easily promoted from the 3s to 3p orbitals. When they decay back to 3s, they emit light at 390.0 and 390.6 nm. The reason for two lines is spin-orbit coupling. Sometimes the spin angular momentum of an electron is aligned with the orbital angular momentum, and sometimes opposite. There is a slight energy difference.
Sodium can be excited a variety of ways. Heating does it. Sodium vapor lamps do it with an electrical discharge. An electric pickle does it with a current.
Sodium can also flouresce. Here is a pay walled paper describing it.
I can only describe in general terms why a given substance has a given color. When an electron drops from one orbital to another, it loses energy. If the energy is emitted as light, the frequency and wavelength are related to the energy loss by $E = h \nu = hc/\lambda$. The frequency and wavelength determine the color. For sodium, the color is in the middle of the visible spectrum.