Part a. the diagrams below each show the motion of a distant star relative to earth (not to scale). the red arrows indicate the speed and direction of the star's motion: longer arrows mean faster speed. rank the stars based on the doppler shift that we would detect on earth, from largest blueshift, through no shift, to largest redshift.
part b. each diagram below shows a pair of spectra with a set of spectral lines. the top spectrum always shows the lines as they appear in a spectrum created in a laboratory on earth ("lab") and the bottom spectrum shows the same set of lines from a distant star. the left (blue/violet) end of each spectrum corresponds to shorter wavelengths and the right (red) end to longer wavelengths. rank the five stars based on the doppler shifts of their spectra, from largest blueshift. through no shift, to largest redshift.
part c. an important line of hydrogen occurs at a rest wavelength (as measured in a laboratory) of 656 nm (a nanometer (nm) is a billionth of a meter). each diagram below has this line labeled with its wavelength in the spectrum of a distant star. rank the motion of the stars along our line of sight (radial motion) based on their speed and direction, from moving fastest toward earth, through zero (not moving toward or away from earth), to moving fastest away from earth.