Question

Which does the shift of the hydrogen absorption spectrum of a galaxy provide evidence for? Select the three correct answers.
Responses

motion of the galaxy
motion of the galaxy - no response given

temperature of the galaxy
temperature of the galaxy - no response given

expansion of the universe
expansion of the universe - no response given

composition of the universe
composition of the universe - no response given

The Big Bang theory
The Big Bang theory - no response given

number of stars in the galaxy

Answer 1

- Motion of the galaxy (Doppler shift of the lines)
- Expansion of the universe (systematic redshift of distant galaxies)
- The Big Bang theory (cosmological redshift is key evidence for an expanding universe originating in the Big Bang)