What a light year really is:

Look, I know a lot of people will already know this, but just to clarify:
A light-year is a measure of DISTANCE. NOT TIME. So, do not say 'In some light-years time'. Please, just don't.
A light year is the distance light travels in a year (According to Google : 9.4605284 × 10¹⁵ metres i.e. a very VERY long distance!)