1. Title: 30.1 Galaxies and The Universe
The Expanding Universe: Redshift

2. Objectives
Students will be able to explain how red shift implies an expanding universe.

3. Word of the Day
Doppler Effect: A change in the observed frequency of a wave, as of sound or light, occurring when the source and observer are in motion relative to each other, with the frequency increasing when the source and observer approach each other and decreasing when they move apart.

4. The Expanding Universe
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1929: Edwin Hubble discovers the universe is expanding.
How?
Noticed that finger prints of elements in stars were not in correct place.
They were there, but they had been shifted.

5. The Expanding Universe
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Redshift: The increase in wave length of radiation emitted by a celestial body as a result of the Doppler Effect.

6. Visible Color Spectrum
The finger prints of elements within celestial objects that are moving away from us get shifted towards red.