Cosmic Queries - What is a Light Year?

Nigel Goes to Space Join Nigel as he takes you on his journey to the stars and beyond! Subscribe - http://goo.gl/wpc2Q1 What is a light-year? A light-year is a unit of length used to express astronomical distances, about 9 trillion kilometres, or 6 trillion miles. A light-year is the distance that light travels in vacuum in one Julian year, as defined by the International Astronomical Union. Because it includes the word "year", the term light-year is sometimes misinterpreted as a unit of time. Nigel is an internationally acclaimed science populariser and author, specialising in astronomy and space.