We need to get used to the night again
As recently as Feb. 20, 1962, most of Earth was pitch black at night. On that date, as the astronaut John Glenn, the first American in orbit, crossed from the day-lit Earth to the dark side of the planet, the world below awaited answers to its questions. Could a lightning storm be seen from space? How visible were the lights of cities and towns from 200 kilometres above them? Even a few physicists predicted that nothing at all would be visible. For a while Glenn hurtled over the blackness of the Indian Ocean. At last he said, “Just to my right I can see a big pattern of light, apparently right on the coast. I can see the outline of a town.”
It was Perth, Australia, ready to greet the astronaut. Knowing Glenn would pass overhead, the city council had voted to leave its street lights on (not so very long ago, many cities shut theirs off at night), and the people of Perth pitched in, turning on porch lights and headlights, or just pointing flashlights into the sky. The local BP refinery even turned up its gas flare — “a very bright light,” said Glenn. While the rest of the sprawling Australian land mass was cloaked in darkness, Perth gleamed. “The lights show up very well and thank everybody for turning them on, will you?” Glenn said to his ground crew.
How times have changed. By 2020, nearly a quarter of the land area of Earth outside the polar ice caps was lit by skyglow from artificial lights. In NASA’s “black marble” images of our planet at night, pinpricks of light are spreading even in the Arctic, the Sahara Desert, and the heart of the Amazon rainforest, while true darkness has disappeared from whole swaths of the globe, including eastern North America, Western Europe, the Nile River Valley, much of India and eastern Asia — and Perth, which now dubs itself the “city of light.”
For years now, a technological fix has been available to reduce both light pollution and the staggering amount of energy we consume by lighting our lives. Unfortunately, it hasn’t been enough—because our lights are caught up in our consumer mindset.
If you dump plastic into the ocean, or poison soil with mining tailings, or pump carbon dioxide into the atmosphere, the effects play out for years if not centuries, making these problems difficult to truly solve. Not so when it comes to light pollution. “You can literally turn them off,” said Kevin Gaston, a British ecologist who studies the effects of artificial light. “You can regain some of what you’ve lost quite easily.”
The same goes for saving energy. While green technology is advancing slowly on many fronts, energy-efficient light-emitting diodes (LEDs) are widely available and affordable. They commonly burn at least 75 per cent less energy than older models of lights, and well-designed fixtures also prevent light pollution by directing their brightness only to those areas that need to be lit. A worldwide system of environmentally friendly lighting is so achievable that light scientists have argued that we should pursue it as a way to inspire confidence that we can resolve tougher global challenges.
Instead, the opposite is happening. As LEDs gain popularity, there are growing indications that we’re spending the money we save on energy costs to buy: more lighting. A boom in “media architecture” — enormous video screens that play out across the facades of buildings — is now underway around the world. The two towers of the International Youth Cultural Centre in Nanjing, China, are a standout example: 700,000 LED lights cover the 60-storey building’s exteriors, which are also floodlit from the ground. The “Mighty Lights” on the Hernando de Soto Bridge in Memphis, Tennessee, involve 10,000 colour-controllable lights that cover the entire bridge structure. Meanwhile, on the famous Bahnhofstrasse, an upscale shopping street in Zurich, Switzerland, video screens increased by more than 40 times in the past five years alone. A similar explosion in decorative lighting is taking place in private yards and homes. “If we improve the energy efficiency of all the outdoor lighting by switching to LED lights, but increase the total amount of advertising and floodlighting, then we might not actually save much energy on a global scale or national scale,” said Christopher Kyba, a Canadian physicist and light pollution researcher at the GFZ German Research Centre for Geosciences.
When Kyba and his colleagues looked at changes in the amount and brightness of light around the world between 2012 and 2016, they found that most places were gradually growing brighter. Only a few nations were dimming, almost all of them war-torn or in the throes of economic decline. They were places where consumption had slowed.
Can we become reacquainted with the night?
Over the past decade, many British towns and boroughs began to save money by dimming lights late at night, or even turning them off. Recent research showed no change in the number of traffic accidents and no increase to the crime rate. (Some evidence suggested that crime declined in communities that had dimmed their lights.) Most people simply didn’t realize or care that their street lights had been turned off. “It’s just one of them things, street lights, doesn’t really make much difference,” said a bartender who regularly heads home from work after lights out in one rural English county.
That the return of darkness might go largely overlooked should not surprise us, Kyba said. Most visitors to Berlin don’t realize that the city is unusually dimly lit unless it’s brought to their attention; when Vienna turned down its lights by 50 per cent for one hour each night, almost no one but astronomers took note of the fact (and the astronomers were delighted). Similarly, LED bulb lifespans are often measured according to how long it takes for the bulb’s light to fade by more than 30 per cent, which is the point at which most people will realize that the bulb is no longer performing properly. That’s a decline in brightness of a third before we’re even expected to notice.
What does catch our attention is the night itself. In the UK surveys carried out where lights had been turned down, the most common reaction was pleasure at seeing the nighttime sky; when air and light pollution sharply declined during the pandemic, people in cities worldwide thrilled at the crispest view of the stars some had seen in their lifetimes. The spread of light around the world in the past century has been described as the “conquest of the night,” and as in any conquest, there were losses as well as gains. When street lights first began to spread through Japan, one writer worried that the Japanese would lose their appreciation of shadows. When Paris became the original ville lumière in the 1860s, lighting itself with twenty thousand gas lamps, the loss of night was a matter of debate: some felt it created a pressure to conform; others that it would be the end of the “safety of darkness.”
In 1998, 36 years after his original orbits around Earth, astronaut John Glenn returned to space. He witnessed a nighttime world transformed: nearly every one of the world’s cities and towns is now a “city of lights.” Still, Perth and its citizens once again put on every light for him. What Glenn said this time around was not recorded by the ground crew. According to his fellow astronauts, though, when the spacecraft he was travelling in once again hung over the city, Glenn said, “Wow. Perth is a lot bigger than the last time I saw it.” Then he said, “Okay, guys, you can turn them off now.”
A world that stops shopping is a darker place, and maybe that’s an idea whose time has come. Still, there is something symbolic about stepping back into darkness that worries us. The widespread taming of fire, some half a million years ago, was one of the most consequential moments in human evolution, banishing the night, and lighting the darkness with electricity is still seen as a milestone of development. In the UK, even those who enjoyed walking by the newly visible starlight were also troubled by whether it represented a backward step for civilization and progress. There was even something eerie, during the pandemic, about the vanishing oil wells as seen in images taken from orbit. They looked like stars being blotted out of the sky, the same way that real stars have been disappearing from our brightly lit nightscapes.
The first days after the world stops shopping have this same duality. There is a spreading quiet and calm, a sense of time stretching and older lifeways returning. There’s still food on the table and clothes in the closet. It’s peaceful, nostalgic, maybe even a little too slow. Beyond it all is a gnawing sense that much, much harder times are coming.