Question

1. in the diagram to the right, the spectral lines of hydrogen gas from three galaxies, a, b, and c, are compared to the spectral lines of hydrogen gas observed in a laboratory. what is the best inference that can be made concerning the movement of galaxies a, b, and c? a. galaxy a is moving away from earth, but galaxies b and c are moving towards earth. b. galaxy b is moving away from earth, but galaxies a and c are moving towards earth. c. galaxies a, b, and c are all moving towards earth. d. galaxies a, b, and c are all moving away from earth. unit 1 origin of the universe quiz score: / 10

Explanation:

The Doppler - effect for light is used here. Red - shift indicates that an object is moving away from the observer. In the spectra of galaxies A, B, and C, compared to the laboratory hydrogen gas spectral lines, the lines of all three galaxies are shifted towards the red end. This implies that all three galaxies (A, B, and C) are moving away from Earth.

Answer:

d. Galaxies A, B, and C are all moving away from Earth.