85 trillion miles away o Light year the distance that light travels in one

# 85 trillion miles away o light year the distance that

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Nearest star to Earth, Alpha Centauri, lies 40.85 trillion miles away o Light year- the distance that light travels in one Earth year, equals about 6 trillion miles o The nearest galaxy to ours, Andromeda, lies 2.2 million light years away 1.3 Forming the Universe o Doppler effect- how it modifies the light seen in telescopes o The Universe expands o Expansion began during the Big Bang, 13.7 billion years ago 1.3.1 Waves and the Doppler Effect o Waves- disturbances that transmit energy from one point to another in the form of periodic motions. o Wavelength- the distance between successive waves o Frequency- the number of waves that passes a point in a given time interval o When waves closer together, the wavelength is smaller o Doppler effect- the change in frequency that happens when a wave source moves o Light energy also moves in the forms of waves o The color you see depends on the frequency of the light waves- red light has longer wavelength (lower frequency) than does blue light. o If a light source moves away from you, the light you see becomes redder. As the light shifts to longer wavelength or lower frequency. o If the source moves toward you, the light you see becomes bluer, as the light shifts to higher frequency. The red shift and the blue shift 1.3.2 Does the Size of the Universe Change? o The light of distant galaxies displayed red shifts relative to the light nearby stars. The red shifts consequence of the Doppler Effect, distant galaxies moving away from Earth at an immense velocity. ALL distant galaxies are moving rapidly

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