To describe distances outside our solar system,
trillions and quadrillions of kilometers
gets to be a drag. So we get out the
BIG meter stick and
measure things in
light-years.

A light-year is the distance light travels in a year,
traveling at a speed of 300,000 kilometers/second
(186,000 miles per hour).

To find out the exact number of kilometers
in a light year, multiply the number of seconds
in a year by 300,000 kilometers per second.