"Genius" but doesn't know that Light Years aren't even a measurement of TIME, but rather DISTANCE. The "light" measurement system goes all the way from "year" to "second" (To my knowledge it is: Year --> Day --> Hour --> Minute --> Second), with "year" equaling 5.879Qa Miles (9.461Qa Kilometers), & "second" equaling 186K Miles (299K Kilometers).
I don't personally know why they used a time measurement in the name of a distance measurement, but I believe it's based on the distance light travels within that timeframe (ie: 670Bil Miles / 1.07Tril Kilometers traveled in an hour).