What does red shift evidence mean?

• A. Light from galaxies is blue shifted indicating galaxies are approaching us.
• B. Light from stars glows red due to hotter temperature.
• C. Light from galaxies is shifted toward red, meaning galaxies are moving away from us (expanding).
• D. The red color of distant quasars indicates ancient light.

Answer: (C)

Red shift evidence means light from distant galaxies is stretched to longer wavelengths, so their spectral lines shift toward the red end of the spectrum. This stretching happens because those galaxies are receding from us, reflecting the expansion of the universe. The larger the redshift, the faster the recession and the farther away the galaxy (and the farther back in time we are seeing it).

Blue shift would imply galaxies are moving toward us, which isn’t what this evidence shows. Reddening from heat is about temperature and not about motion, so it’s not what red shift describes. The idea that red color alone signals ancient light isn’t precise; redshift specifically refers to the wavelength shift caused by expansion, not just the light’s age.