Question

the diagram shows the spectral lines for a galaxy.
blue
red
based on the diagram, a student claims that the universe is expanding. which statement correctly analyzes the claim?
the claim is correct because the spectral lines shift to the red end of the spectrum when a galaxy spins faster.
the claim is incorrect because the spectral lines in the red end of the spectrum are obtained only from red giant stars in a galaxy.
the claim is incorrect because the spectral lines in the red end of the spectrum are obtained when the light from a galaxy passes through a nebula.
the claim is correct because the spectral lines shift to the red end of the spectrum when a galaxy moves away.

Explanation:

To determine the correct statement, we analyze the concept of redshift. The redshift (spectral lines shifting to the red end) occurs when a galaxy moves away from us, which is evidence for the expanding universe.

• The first option's reasoning (galaxy spins faster) is incorrect.
• The second option's reasoning (red spectral lines only from red giant stars) is wrong as redshift is about motion, not star type.
• The third option's reasoning (light passing through nebula) is incorrect; redshift is due to cosmic expansion - related motion.
• The fourth option correctly links redshift (spectral lines to red end) with a galaxy moving away, supporting the expanding universe claim.

Answer:

The claim is correct because the spectral lines shift to the red end of the spectrum when a galaxy moves away. (The fourth option in the list of choices, which states "The claim is correct because the spectral lines shift to the red end of the spectrum when a galaxy moves away.")