# Astronomers observe that light from distant galaxies is red-shifted. Explain what red-shift tells us about the universe, and describe how the amount of red-shift changes with distance from Earth.

> WJEC GCSE Physics (Wales) — 2.1 Light, lenses and the universe · Explain · 4 marks

## Mark scheme (4 marks)

1. Red-shift means the wavelength of light from a galaxy is longer / shifted towards the red end of the spectrum
2. Red-shift shows that galaxies are moving away from us / the universe is expanding
3. More distant galaxies show a greater red-shift
4. More distant galaxies are moving away faster / there is a relationship between recession speed and distance

## Key terms

- [red-shift](https://www.gradenine.co.uk/glossary/red-shift)
- [universe](https://www.gradenine.co.uk/glossary/universe)

## Related

- [Revision notes for WJEC GCSE Physics (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/astronomers-observe-that-light-from-distant-0fc295de) · Published by Druglandscape Ltd.