Light-year
n. a unit of length used by astronomers to measure interstellar distance (the distance between stars). A light-year is defined as the distance that light will travel in a year. If the speed of light is 186,000 miles per second (300,000 km per second), then calculate the distance that light will travel in one year.
Calculation:
186,000 miles/second x 60 seconds/minute x 60 minutes/hour
x 24 hours/day x 365 days/year = 5,865,696,000,000 miles