Here's why:
* Emission Spectrum: An emission spectrum is produced when excited atoms release photons of specific wavelengths as their electrons transition back to lower energy levels. The emitted photons correspond to the energy difference between the energy levels.
* Nebulae: Nebulae are vast clouds of gas and dust in space. They often contain excited atoms due to various processes, including the energy from nearby stars.
* Electron Transitions: When an electron in an atom absorbs energy, it jumps to a higher energy level. This is an unstable state. To return to a stable state, the electron releases the absorbed energy in the form of a photon. The energy of the photon corresponds to the difference in energy between the two levels.
Therefore, the specific wavelengths of light emitted by a nebula create a unique pattern of bright lines in the spectrum, characteristic of the elements present in the nebula. This is known as an emission spectrum.
