The orbital velocity of the earth can be calculated in reference to other objects in space such as stars. A spectrum of the object can be used because the Doppler shift of the earth’s movement can be measured. The earth is moves closer to objects during one half of its orbital path. This is recorded on the spectrum as red shifted light. On the half of its orbit it is moving away from the object and the spectrum measures this movement as blue-shifted light.
This experiment uses the star named Arcturus to measure the spectrum shift during earth’ ...