The poetry of a lightyear lies in its dreamlike definition: a unit of length equal to the distance that light travels in one year in empty space. Just under 6 trillion miles (or 10 trillion kilometers if you prefer). A unit of measurement, in other words, that belongs to the gods. Who, it might be noted, every so often catch us religiously tracking our frequent flyer miles, and try not to smile.
March 27, 2013