# Explain what is meant by red shift and describe what the red shift of light from distant galaxies tells scientists about how the universe began.

> Eduqas GCSE Physics — 10.2 Red shift and the Big Bang · Explain · 4 marks

## Mark scheme (4 marks)

1. Red shift is when light from a source moving away from an observer is shifted towards longer wavelengths / the red end of the spectrum
2. Almost all distant galaxies show red-shifted light, meaning they are moving away from us
3. Galaxies that are further away show greater red shift, meaning they are moving away faster
4. This evidence supports the Big Bang theory — the universe started from a very small point and has been expanding ever since

## Key terms

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

## Related

- [Revision notes for Eduqas GCSE Physics](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-what-is-meant-by-red-be74f5e3) · Published by Druglandscape Ltd.