Each spectral line of a particular wavelength emitted or absorbed by the atom when one of its electrons jumps between a higher and a lower orbit Each element has its own unique set of allowed electron orbits so each element has its own characteristic set of spectral lines
stars are blazing balls of gas where many kinds of atoms emit light of all colors This light emitted from the star's surface passes through the star's atmosphere there atoms of each element absorb their characteristic wavelengrtns so a pattern of dark lines crosses the continuous band of colors the star's spectrum
propar motion
peryear
A degree is equat to 3600