OR, TO BE EXACT: Twelve (12) FAA-approved high-intensity white flashing obstruction beacons, nine (9) FAA-approved medium intensity flashing red beacons, eighteen (18) FAA-approved steady-burning obstruction lights, three (3) FAA-approved red/white antenna beacons

As children, we had them in our bedrooms: night-lights, those miniaturizations of the daytime sun, those dim protests against the terrifying peopled dark. Small but powerful, they held off the luminous-eyed aliens lurking in our closets, made us invisible to ghosts. Their plastic switches rocked off and on with satisfying clicks. Elaborate versions, made for children who suffered persistent and brilliant terrors, had shades of stained glass or extruded plastic, of sand-dollars or alabaster. Some had revolving shades that would send tropical fish or carousel-horses spinning endlessly around the walls of the room.

Now, as adults, we’re not allowed to admit we’re afraid. Our night lights indicate the way to the bathroom or keep us from tripping down stairs in the darkened theater. But our cities themselves are beacons in the dark, night-lights pushing out against the vast dark of our continents, and those cities have their own internal night lights, their own beacons. In San Francisco it’s the Sutro Tower, a nine-hundred-seventy-seven-foot broadcast tower on the city’s highest hill. Its topmost riggings float above the five o’clock fog like the riggings of a ghostly ship. At night, eighteen beacons burn a constant red; nine signal beacons flash their warning twenty times a minute. High up, three antenna beacons flash a paler red, their white day-bulbs shielded with red plastic filters.

—Julie Orringer