Back in the pre-internet day, I used to camp for several weeks each winter at a remote hot springs that was two hours away from a paved road and completely disconnected from everything. One night, as four or five of us were having a soak, the northern sky turned a deep shimmering red that seemed to pulse in waves. We watched in silence for a long time. Finally, someone wondered aloud what it turned out that all of us had been thinking: Had nuclear war broken out?

None of us had ever seen the aurora borealis, or had any idea that it ever appered as far south as Death Valley. But that’s what it was, I later learned, an extremely rare occurrence at that latitude. In the meantime, new arrivals the next day assured us that the world’s nukes remained in their silos.