Astronomers calculate speed of dstant stars and galaxies using which of the following phenomena?
- A.Beats
- B.Interference
- C.Super position principle
- D.Doppler effect✓
Why D is correct
The Doppler effect shifts spectral lines depending on radial velocity of astronomical objects; this shift is used to measure their speed. Beats and basic interference are not used for large-scale radial velocity measurements.