BRAINCAKEDark Matter
Dark matter is matter that does not emit or absorb electromagnetic radiation, so it cannot be seen. It can only be detected through its gravitational effects.
Evidence from galaxy rotation. Stars orbit the centre of a spiral galaxy, the gravitational force providing the centripetal force:
GMm/r2 = mv2/r, so v = √(GM/r)
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Key terms in this lesson
- gravitational lensing
- The bending of light from a distant object by the gravity of a massive body, such as a galaxy, lying between it and the observer.
More in Space
- White Dwarfs, Neutron Stars and Black Holes
- Trigonometric Parallax
- Standard Candles
- The Doppler Effect and Red Shift
- Hubble's Law
- The Age of the Universe
- The Expanding Universe
- The Fate of the Universe
All 18 lessons in Space · All Edexcel A-level Physics topics