Science Space After the Big Northridge Earthquake, a Mysterious Cloud Appeared Above LA – Here's What It Was By Melissa Breyer Editorial Director Hunter College F.I.T., State University of New York Cornell University Melissa Breyer is Treehugger’s editorial director. She is a sustainability expert and author whose work has been published by the New York Times and National Geographic, among others. our editorial process Melissa Breyer Updated April 03, 2019 CC BY 2.0. View over Hollywood and LA from Mulholland Drive. Mike Knell/Flickr Share Twitter Pinterest Email Science Space Natural Science Technology Agriculture Energy Calls came into emergency centers and even the Griffith Observatory from LA residents who described seeing a “giant silvery cloud.” In the pre-dawn hours of January 17, 1994, an earthquake with a magnitude of 6.7 struck Los Angeles' densely populated San Fernando Valley. With its epicenter located about 20 miles west-northwest of downtown Los Angeles, the Northridge earthquake was the third major earthquake to occur in California in 23 years. It was the state’s most destructive earthquake since the San Francisco earthquake of 1906 and the costliest earthquake to ever strike the U.S. The earthquake occurred just after 4:30 AM local time and people did what people do after an earthquake, and especially after an earthquake that knocks out all the power, as this one did – they poured outside into the streets. Many of them looked up and were apparently freaked out by what they saw ... what The New York Times described as a “giant silvery cloud” over the shaken city. The Times reported that numerous calls came into emergency centers, and even the Griffith Observatory, about this eerie happening in the sky. Do you know what that cloud was? The Milky Way. Yes, that's right – the galaxy that contains our Solar System. The diaphanous band of stars – some 30 degrees wide that has been inspiring wonder ever since humans have been looking up to the heavens – had never been seen by legions of Angelinos, thanks to the city's formidable light pollution. But once the lights were dimmed by the outage, there the shimmering Milky Way appeared. View of Milky Way over Cathedral Rock, Arizona. Coconino National Forest/Flickr/CC BY 2.0 I often think about what early humans must have thought about nature's more dramatic tricks; things like lightning must have seemed completely supernatural. For modern people not knowing what the Milky Way looks like, it may very well have felt the same, having it appear out of nowhere. It's startling to think that we have lost not only sight of our own galaxy, but the nighttime sky as well – so much so that the sudden appearance of a swath of stars would incite 911 calls. But it's really no surprise. More than 80 percent of the world and more than 99 percent of the U.S. and European populations live under light-polluted skies. And according to the world atlas of artificial sky luminance, the Milky Way is hidden from more than one-third of humankind, including 60 percent of Europeans and nearly 80 percent of North Americans. I have written about the sad tragedy of light pollution many times before – you can read much more on the topic in the related stories below – but I found this anecdote so profound that I had to share it. Let it serve as a reminder to use your evening lights sparingly, urge local businesses to practice night-sky lighting, and talk to legislators about the importance of tackling light pollution. And when all else fails, if you live in a recklessly light-polluted city, do whatever it takes to get out of town and catch a glimpse of one of the most beautiful sights in the world, the galaxy we call home.