We live in a world defined by inches, feet and miles (or centimeters, meters and kilometers, if you prefer), and it’s not difficult for most of us to comprehend sizes and distances given in these ...

Who even knows what an "astronomical unit" is anyway? When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. Add us as a preferred source on Google Have ...

The light-year is an indispensable unit of measurement for anyone trying to understand outer space. Get a group of astronomers talking, and you’ll hear them say “light-years” about as often as you ...