19. Speed of light A star on the axis of the earth's orbit appears to have a circular orbit of angular diameter of 41.2 seconds of arc. (a) How is this angle related to the earth's speed in its orbit and the velocity of photons received from this distant star? (b) What is the speed of light as determined from the data in Part (a)? Hint: Compare the situation "Cloud-Marathoner" from exercise 19. with "Star-Earth"