Cities of Blinding Light: When Star Gazing Becomes Impossible

A new study says 80 percent of the population lives under light pollution.

In 1994, an earthquake hit Los Angeles at 4:30 AM. Power was knocked out and startled residents ran outside, bathed in darkness. As they looked up, they saw something they had never seen before; the sky was filled with stars. Unused to the sight, a number of people called the local observatory to find out what was going on, the Los Angeles Times reported.

Star gazing in big cities is an increasingly rare phenomenon. The city lights drown out the stars by brightening the sky. Cities have gotten so big that 80 percent of the world lives under light pollution, and more than one-third of humanity can’t see the milky way at all, a new study in Science Advances found.

Since ‘94 city populations have ballooned. Already, 54 percent of the world population live in cities, according to the United Nations. That’s around 3.5 billion people globally. By mid-century, the number of people living in cities in Asia is expected to grow by 90 percent.

To accommodate this growth, cities will have to expand and in the process light up more places.

While artificial lighting has increased productivity by extending the work day, it disrupts our sleeping patterns. Disrupted sleep is linked to disorders such as depression, cardiovascular disease and cancer, studies show.

And our need for light is also disrupting animals — especially nocturnal ones.

Migratory birds that use the stars as guides for their migration are confused when they pass through cities.

Artificial light on beaches poses a problem for sea turtles, discouraging them from nesting in their ancestral breeding grounds. Young hatchlings can’t always find their way to the water because they’re thrown off by the light.

Even though we need light, we could cut down on how much we’re using, the authors of the new study said. Better urban planning could drastically reduce how much light we’re using.

There’s a big difference between having a well-lit street, which means everybody can get around really easily and safely, and a brightly lit street, which could mean there’s too much light and it’s not helping anyone.

Dr Christopher Kyba, from the German Research Centre for Geosciences in Potsdam