Demand for protective eclipse glasses has been intense. Streetlights on automatic sensors and some cars’ automatic headlights could switch on briefly, mistaking the dip in light for dusk. Timing: A Nearly Two-Hour ShowThe eclipse begins shortly after 6pm and runs for close to two hours. Proper eclipse glasses, typically only a few pounds, remain the safest bet, though stock has largely dried up. Ordinary sunglasses don’t cut it, and old eclipse glasses kept from 1999 shouldn’t be trusted either, as their filters degrade over time.