BRAINCAKEHubble's Law
In the 1920s, Hubble measured the red shifts of galaxies, giving their recession velocities, and their distances, using standard candles such as Cepheids. He found that the further away a galaxy is, the faster it is moving away from us.
Hubble's law: the recession velocity of a galaxy is directly proportional to its distance:
v = H0d
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Key terms in this lesson
- recession velocity
- The speed at which a galaxy is moving away from an observer because of the expansion of the universe.
More in Space
- White Dwarfs, Neutron Stars and Black Holes
- Trigonometric Parallax
- Standard Candles
- The Doppler Effect and Red Shift
- The Age of the Universe
- The Expanding Universe
- Dark Matter
- The Fate of the Universe
All 18 lessons in Space · All Edexcel A-level Physics topics