Voyager 1, the NASA space probe that has traveled farther from Earth than any other human-made object, is closing in on a remarkable milestone. Actually, let’s call it a 16.09-billion- milestone. That’s the distance a photon can travel in a single day, which is to say the Voyager 1 spacecraft will be exactly one light-day away from our planet on November 18 at 5:18 a.m. EST.

At that moment, a radio signal sent from Earth would take 24 hours to reach Voyager 1, and then it would take another 24 hours for the probe’s response to come back. Imagine on a Friday morning telling your oven to turn on, but you don’t receive confirmation that it’s hot until Sunday. And by that point, the oven would have been baking whatever was inside for most of Saturday. That is the kind of delay that NASA’s Voyager team must work with.

Communicating with a machine at this superlative distance is “a pretty incredible endeavor,” Princeton University research scientist and heliophysicist Jamie S. Rankin tells Popular Science .…