Practice Questions

1. Explain what is meant by the term red shift.

Red shift is the increase in the wavelength of light from a galaxy or star that is moving away from us.
This causes the light to shift towards the red end of the spectrum.

2. If a galaxy were moving towards us, how would this affect the light that we would receive from the galaxy.

If a galaxy were moving towards us, the light we receive from it would be blue-shifted.
This means the wavelengths of the light would become shorter, shifting towards the blue end of the spectrum.

3. How does the red shift provide evidence that the universe is expanding?

Red shift provides evidence that the universe is expanding because it shows that distant galaxies are moving away from us.
The further away a galaxy is, the greater its red shift, meaning it is moving away faster.
This suggests that space itself is stretching, so the universe is expanding in all directions.