If sun is the source of light then is it possible that the speed of light might increase depending on the mediums its going through or its not possible.
The speed of light in a vacuum, or c, is 299,792,458 meters per second. Any other medium will slow light down. For example light takes about 40% more time to go through glass than vacuum. But media that would increase the velocity of light would violate fundamental laws of physics and can therefore not exist.