1. Effects of Motion and Gravity
GAVRT Chapter 5

2. Doppler Effect
Apparent change in frequency and wavelength due to relative motion between wave source and receiver
No change in speed of wave
Frequency constantly higher as objects approach and lower as recede from one another
Hewitt diagram or page 43 of text

3. Red and Blue Shifts
Spectral lines shift due to relative motion between source and Earth.
Shift indicates direction of source relative to Earth
Blue shift means object is approaching Earth
Red shift means object is receding from Earth (most objects)
Hubble constant allows us to relate the red shift of an object to its distance.
Depends on observation that further objects are moving faster
Current estimates of constant km/s/per million parsecs

4. Gravitational Effects
Gravity can lengthen wavelength of radio emissions mimicing Doppler shift
Gravitational lensing causes light to bend around massive object producing multiple images of otherwise hidden object
Lens diagram on page 45
Photograph of gravitational lens galaxy

5. Superluminal Velocities
Some quasars appear to move faster than speed of light
Explanation is that speed is a projection effect of quasar traveling at an acute angle to us
Diagram on page 46

6. Occultations When one celestial body passes by another Examples
Spectroscopic studies of occultations allow for the examination of an objects atmosphere