Awasome Speed Of Light In Ly Year References. The light year (ly) is a unit of length that is the distance light travels in a vacuum in one earth year. When we use powerful telescopes to look at distant objects in space, we are actually looking back in time.
Ly) [1] is the distance that light travels in empty space in one year. In one year, light travels about 5,880,000,000,000 miles or 9,460,000,000,000 kilometers. But how much time would have passed for the traveller on the ship?
