Question

which statement accurately describes how the understanding of the doppler effect is applied to the study of galaxies?
it was used by hubble to measure the velocities of galaxies.
it was used to monitor galaxy motion through changes in sound waves.
it indicates a galaxy moving toward earth through red shift.
it indicates a galaxy moving away from earth through blue shift.

Explanation:

• Option 1: Hubble used the Doppler effect (specifically the redshift of light from galaxies) to measure the velocities of galaxies. This was a crucial part of his work that led to the discovery of the expansion of the universe.
• Option 2: Galaxies are studied using light waves (not sound waves, as sound cannot travel in the vacuum of space) to monitor their motion.
• Option 3: A galaxy moving toward Earth would show a blue - shift (shorter wavelength of light), not a red - shift. Red - shift (longer wavelength) indicates a galaxy moving away.
• Option 4: A galaxy moving away from Earth shows a red - shift, not a blue - shift. Blue - shift is for objects moving towards the observer.

Answer:

It was used by Hubble to measure the velocities of galaxies.