Slow Light

The theory of relativity suggests that the speed of light is a constant, in a vacuum. That is why the time sunlight takes to reach Earth (8 minutes and 20 seconds-ish) can only be regarded as an approximate. Science, if you can believe in such magic, has taught us that light can be slowed. From its 300,000 km/s in a vacuum, down to 225,000 km/s in water and 200,000 km/s in glass. 

This is called refraction, or ‘slight change in light’s direction’. Add gravity which effectively bends light. Is that why these images only reveal themselves at the very end of the sunset? 

The lower the sun, the more thickness of air (humidity) its rays will have to propagate. Thus, effectively slowing the speed of light. Slow Light.

What if I could slow it even further? And not just by the massive chunk of glass that is my lens. What if I added another piece of glass in front of the lens? And what if I exchanged my full-frame camera with a medium format one to effectively triple the image resolution? I guess the question would be where to next? Water?