This is Part 1 of a new series on interstellar comets.

Imagine you live in a small town. Maybe it’s easy for you to imagine because you actually do. You’ve spent your whole life there. You know all the people, and all the people know you. Years go by. Decades. The same faces at the same corner store, the same routes to the same places, the same sky overhead. It’s comfortable. Predictable. You could walk the whole thing blindfolded and never trip.

And then one day a car drives through. It’s got a strange license plate. It’s not even from the next state over — it’s from across the country. Across the world. It’s from a completely different country. It doesn’t stop, doesn’t slow down. It blasts by so quickly that by the time anybody notices, it’s already on the outskirts of town (although, to be fair, except for the corner store the whole town can be considered “outskirts”).

That’s what happened to us in 2017.…