What is exactly heard coming towards the Earth or going away from the Earth with the doppler shift and how is it tracked?
Belleview Middle School, Ms. Lin’s 8th grade classroom ANSWER: In astronomy, the doppler shift refers more often to light waves than sound waves. So what is actually measured is the wavelength of light coming to Earth from a distant star or galaxy. If the star or galaxy (or whatever it is that is being observed) is moving towards the Earth, the light will be “blue shifted”, ie. it will appear to have a shorter wavelength (or “bluer color”) than a non-moving source of the same light. Conversely if the star or galaxy is moving AWAY from Earth, it will appear “red shifted”, or longer in wavelength (redder in color) than a non-moving source. Astronomers “track” the motion of distant objects in space by measuring the red or blue shifts of light from different objects. They use an instrument called a “spectrometer” to very carefully measure the wavelength of light from various objects and then compare that measurement to experiments with non-moving light sources in the lab to derive the rela
