Time x speed = distance Speed x distance = time Distance x time = speed I think thats how it works. So there are times when you say "the speed of light" it means time of distance light travels. So there are times it time can be distance. Hope this answer your question
The highest distance that has been measured is giga light year aka gly. Its equal to 307 parsecs.. giga light years are used to measure the distance between quasars