Question

How do changes in light wavelengths support the idea that the universe is expanding?

A. Light from other galaxies shifts toward the blue end of the spectrum, which shows that the galaxies are moving away from Earth.

B. Light from other galaxies shifts toward the red end of the spectrum, which shows that the galaxies are moving away from Earth.

C. Light from other galaxies shifts toward the red end of the spectrum, which shows that the galaxies are moving toward Earth.

D. Light from other galaxies shifts toward the blue end of the spectrum, which shows that the galaxies are moving toward Earth.

Answer 1

As per the Doppler's Effect

B. Light from other galaxies shifts toward the red end of the spectrum, which shows that the galaxies are moving away from Eart

Answer 2

B. Light from other galaxies shifts toward the red end of the spectrum, which shows that the galaxies are moving away from Earth.

Step-by-step explanation:

As per Doppler's Effect wavelength and frequency of a wave will change with respect to an observer depending on observer's movement. If the observer moves closer, the spectrum will shift towards blue end and if it moves away, the spectrum will shift towards the red end.

When Spectrums of distant galaxies were observed we saw that the spectrum shifts towards the red end. This indicated towards the movement of galaxies away from Earth. This is also known as Red shifting. This also proves the Big Bang theory and that universe is expanding.