AST 104 Lecture Notes - Lecture 19: 30 Foot Fall, A Reminder, Edwin Hubble
Document Summary
Lecture 19: the doppler effect and galaxy motion. All kinds of light, of all wavelengths, travel at a fixed speed. Our eyes detect different wavelengths of visible light as different colors. There is a spectrum of wavelengths shorter and longer than visible light. The change in frequency or wavelength of a wave in relation to an observer who is moving relative to the wave source. Applies to light, sound waves, mechanical waves, etc. Remember, we"re talking about a change in pitch (frequency), not volume. For light, we"re talking about a change in color (frequency), not brightness. Redshift - a shift to a longer wavelength. Blueshift - a shift to a shorter wavelength. An observer only sees a shift due to the amount of motion directly towards or away from them. The faster the source, the larger the effect. In 1912, vesto slipher made spectrographic studies of the brightest spiral nebulae (galaxies) to determine their composition.
