What is a light year?
A light year is the distance light travels in a year's time, in space. Light travels three hundred thousand kilometers or one hundred eighty six thousand miles per second, so in one Earth year it travels nine point four six kilometers times ten to the twelfth power or nearly six trillion miles.
A unit of astronomical distance equal to the distance that light travels in one year, the exact number is 9.4607 × 1012 km or nearly 6 trillion miles.
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