A light year is the distance light travels in one year.
Light travels at 186,282.397 miles per second
Lets do some math to figure out what a light year is. First we need to figure out how many seconds are in one year.
60 seconds to a minute, 60 minutes to a hour equals 3600 seconds per hour
24 hours a day times 3600 seconds equals 86,400 seconds per day
365 days times 86,400 seconds per day equals 31,536,000 seconds per year
Now lets figure out the distance light travels in one year.
31,536,000 seconds per year times 186,282 miles per second.
That equals 5,874,589,152,000 miles per year.
5 Trillion, 874 Billion, 589 million, 152 thousand miles a year.