Spectroscopy concerns the dispersion of the light of an object into the colors of its components ( i.e. energies). There are two distinctive spectra classes: Continuous and discrete. The light is composed for a continuous spectrum of a wide, continuous range of colors (energies). With discrete spectra, at very distinct and clearly defined colors (energies), one sees only bright or dark lines. Discrete spectra with luminous lines are known as emission spectra; those with dark lines are called spectra of absorption. Spectroscopy is a powerful astronomical tool that helps to collect information about an astronomical object's temperature , density, composition, and important physical processes.