Space is filled with aether. For light, aether acts as a medium (as a reference frame). In other words, light propagates at the same speed through aether. Regardless of the direction of propagation. Earth is moving at different speeds with respect to aether. Therefore, speed of light with respect to Earth is different
Aberration is a phenomenon completed in upper atmosphere. It is the same as refraction. Result of Airy's experiment (tube of telescope is filled with water) is only natural.
Due to aberration, it is said that visible position (direction) of celestial bodies shift beyond the direction of motion of Earth. No, shift will be behind the direction of motion of Earth. This will be clear by illustration of light rays in atmosphere.
Draw trajectory of position of a celestial body (on celestial sphere. returns to source every year). Ellipse of annual aberration will be warped by secular aberration. Daily aberration will be many small circles (365 pearls).
