how far is a lightyear?
The light-year is a unit of length used to express astronomical distances. It is about 9.5 trillion kilometres or 5.9 trillion miles. As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in vacuum in one Julian year (365.25 days). Because it includes the word year, the term light-year is sometimes misinterpreted as a unit of time.