Units of distance: A light-year is the distance a light signal traverses during one year of flight-time, a light-second the distance it traverses in a second, and so on.
The following table translates these units into the more familiar kilometres or seconds: 1 light-second = 300000 km = 186000 mi. 1 light-minute = 18 millionen km = 11 million mi. 1 light-hour = 1.1 billion km = 670 million mi. 1 light-day = 25 billion km = 16 billion mi. 1 light-year = 9.5 trillion km = 6 trillion mi.