# Explain why observations of red-shift from distant galaxies support the Big Bang Theory as the origin of the universe.

> Edexcel GCSE Physics (1PH0) — 7.1 Astronomy (Phys only) · Explain · 4 marks

> Astronomers studying light from distant galaxies notice that the wavelengths of light received are longer than expected. The further away the galaxy, the greater this effect.

## Mark scheme (4 marks)

1. Red-shift is an increase in the wavelength of light received from distant galaxies
2. Red-shift shows that distant galaxies are moving away from us / the universe is expanding
3. The further away the galaxy, the greater the red-shift / the faster it is moving away
4. If the universe is currently expanding, it must originally have started from a single small, hot, dense point / the Big Bang

## Key terms

- [red-shift](https://www.gradenine.co.uk/glossary/red-shift)
- [Big Bang Theory](https://www.gradenine.co.uk/glossary/big-bang-theory)
- [universe](https://www.gradenine.co.uk/glossary/universe)

## Related

- [Revision notes for Edexcel GCSE Physics (1PH0)](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/explain-why-observations-of-red-shift-from-551cd32f) · Published by Druglandscape Ltd.