Hi, this is my first time on the ice in space forum- so hello to everyone. I have only just begun my obsession with the sky, but I think it could be a long and interesting one. Physics was never my strongest subject at uni. but I was wondering about the speed of light. It travels at about 300,000 kms/sec, does this mean that its speed is constant or does a photon accelerate as it is emitted from its source and then reach a maximum speed of 300,000 kms/sec , or is this an average? If light can be bent, distorted or just sucked into nothingness by gravity/black holes, does this change the speed of light and hence the accuracy of distance calculations?