Why must the Sun be eclipsed to measure the deflection of starlight passing near the Sun?
Solution Step 1 of 2 The bending of the path of the light by gravitational field of sun, Light consists of a large number of energy qantas which are known as photons. The phenomenon of bending of photon or the light ray path due to the gravitational field of sun, is referred as gravitational lensing. If we observe a star location during day time, the rays from the star will be bent due to the gravitational field of sun and hence the star will appear at apparent location. As in the figure, Whereas if we observe the same when the sun is eclipsed or blocked(during night time),as the light rays will not be bent by the sun; the location of the star will be at actual position. As in the figure,