apparent change in the frequency of a wave caused by relative motion between the source of the wave and the observer

thing emitting waves (ex star emitting light)

the thing that is emitting waves moves

in front, it bunches up, behind the thing, it spreads out

when it’s moving towards a stationary object, these bunched up waves are observed at a high frequency

moving away - waves observed at a low frequency

look out observatory, see star

light waves emitted are emitted at higher frequency

• higher frequency - blue shift

• lower frequency - red shift

if a star is moving, spectrum is shifted

• blue shift - star moving towards earth, wavelengths of light have been compressed, spectral lines shifted towards blue end

• red shift - star moving away from earth, wavelengths of light become longer, spectral lines shifting towards red end

shift in colour of distant objects not visible with naked eye

• spectroscopy - analysis of light spectra (wavelengths) and the way in which light interacts with matter

elemental fingerprints

• each element gives off unique spectral signature/fingerprint

• can analyze light coming from different objects in space and determine their composition by comparing fingerprints

• emission spectrum - spectrum consisting of several narrow, bright, bands of light

• different elements emit different wavelengths of light