The Novel Optical System of Measuring the Speed of Starlight

We proposed a novel method and implemented an optical system accordingly to measure the speed of starlight by using the well-known speed of light from a terrestrial source, c, as a metric basis. This system consists of a transmitter and a receiver. The transmitter modulated starlight, terrestrial red and infrared lights into pulses simultaneously. These pulses were detected by the distant receiver. A high speed oscilloscope is used to record the pulses arrival times, where the terrestrial infrared pulse and the red pulse are used as the trigger and the reference signals. During the measurement, we employed a terrestrial white light travelling along the exact path of the starlight to calibrate the system. We found that the starlight pulses arrived at the receiver with various degrees of delays, compared with that of the terrestrial white light pulse. The values of the delays are likely related to the relative radial velocities of the stars. The result implies that the measured apparent speed of starlight is not constant.