In 1994, a 6.7-magnitude earthquake jolted through Los Angeles at 4:30 a.m. The shaking woke residents, who discovered the power had gone out citywide. Some left their houses or peeked outside to check on the neighborhood. It was very dark — no streetlights and few cars at that late hour. They looked up at the sky. It was flush with cosmic bodies that had been invisible up to that point — twinkling stars, clustered galaxies, distant planets, even a satellite or two. Then some people became nervous. What was that large silvery cloud that trailed over the city? It looked so sinister they called 911. That cloud was the Milky Way. They had never seen it before.