Retroreflector

We had to go to Earth's Satellite  before we could know exactly where it was. In our travels we left five sets of mirrors behind so we might see in their reflections how far we had come. We look upwards now and count. It takes a beam light roughly 2.5 seconds to travel from Earth to Earth's Satellite and back — we measure our path in reflections of the past.  This is a ritual to remember how far …