How City Lights Have Made the Stars Disappear All Over the Western World

Over 80% of world and 99% of U.S. and European populations live under light-polluted skies. This has implications.

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 A Perseid meteor shower lights up the night sky in Mitzpeh Ramon.
A Perseid meteor shower lights up the night sky in Mitzpeh Ramon.Credit: Tal Nitzan
Moshe Gilad
Moshe Gilad
Moshe Gilad
Moshe Gilad

“Nightfall,” written by Isaac Asimov in 1941, is one of the best science fiction stories ever written. The short story tells of a society that never experienced darkness or the stars in the sky. Their sky was always lit up by six suns, but once every 2,000 years the suns align in such a way that none are visible and the people of the planet Lagash are forced to deal with darkness and the sky filled with stars for the first time. It drives them crazy.

Will something similar ever occur to us? I look up and see the evening sky in the Tel Aviv area. Here and there are a few twinkling stars. Just a few, faded stars, barely overcoming the white glow, the excess of bright artificial light that covers the central region of Israel.

We can only dream about seeing the Milky Way, which we are a part of. The stars are disappearing from our lives. The star-filled night skies, those the romantic poems were written about, are no longer a vision accessible for most of the Western world. In order to see starry skies I had to journey some three hours south to the dark Ramon Crater. For an even more impressive sight of night skies you need to go to the Sinai desert, where the starlight is so strong it really can almost drive you crazy.

An innovative new atlas, recently published as an article in Science Advances magazine (The New World Atlas of Artificial Night Sky Brightness), shows that more than 80 percent of the world and over 99 percent of United States and European populations live under light-polluted skies. Light pollution means that artificial illumination overpowers the natural night sky luminance from the stars, and almost the entire population in these regions has lost the ability to see the stars.

If our goal was to drive out the darkness, then it seems we have succeeded. The big question is what else we have lost along the way. The poetic ability to be amazed by the stars is just one of many that have disappeared, say the authors of the artificial light atlas.

The Observatory in Chile. Credit: AP

The first problem the new atlas solves is how to measure the amount of light pollution and to know how serious it is. Are we only crying wolf and demanding that the Western world – once again – stop its technological progress? A conversation with Prof. Boris Portnov of the Natural Resources and Environmental Management Department at the University of Haifa, one of the authors of the atlas (along with Nataliya Rybnikova from the University of Haifa and other scientists from Italy, Germany and the U.S.), clarifies that the authors’ call to pay attention to light pollution is only the beginning of a long and necessary process toward understanding the issue and dangers involved.

Prof. Boris Portnov.Credit: Moshe Gilad

“The atlas is the basis for future research,” says Portnov. “It will be possible to understand many phenomena in different fields: for example, in medicine – what are the implications of light pollution on the health of the population, or in economics – what does artificial illumination say about the different uses of land around the world.”

The atlas combines precise satellite imagery with innovative means for measuring sky light levels. The scientists present a series of colorful and beautiful maps that show how our night sky is brutally lit up. Europe looks like a bright yellow stain in the satellite photos, without any black holes any more. The U.S. is covered with a similar brightness. The country with the greatest exposure to artificial light in terms of area is Singapore. Densely populated Israel is seventh in this ranking, alongside such small and crowded countries as Qatar, Kuwait and South Korea. The search for black regions, where the residents do not yet suffer from light pollution, leads us to various remote places in South America, Africa and Australia.

Portnov says that the technology is based on repeated satellite imagery of the same spots over long periods of time. Every night the satellite photographs squares of land, 750 meters long on each side, from 8 P.M. to 3 A.M. – when it is possible to determine the level of light pollution. The huge amount of data in these photos are then processed by the scientists. Portnov describes the atlas as “an integration of geographic maps and enormous amounts of information on artificial illumination.”

Night lighting in Ayalon Highway outside Tel Aviv.Credit: Eyal Toueg

He summarizes the findings simply: “When you look at the maps we published, it is possible to understand that the night has ended. Only 120 years ago, total darkness prevailed in the areas we mapped. Now they are lit up all throughout the night with powerful lighting. Only an idiot would think that such an important change in the environment, such a gross distortion of nature, has no far-reaching influences. We simply don’t know to evaluate them completely.”

Spilt milk

A few months ago, when I visited San Pedro de Atacama, a small and very remote town in far northeastern Chile, I looked up at the night skies and was amazed. Only there, on the other side of the world, did I understand what we have lost over the past 30 years.

The comparison between Israel’s Dan region and San Pedro de Atacama is unfair. The night skies over the Chilean desert are considered to be the clearest in the world. They have an especially successful combination of a small population, minimal artificial lighting, dry climate, almost zero humidity in the atmosphere and an altitude of over 3,000 meters. All these enable visitors to see the Milky Way quite well. The feeling there is that it is possible to reach out and touch the stars. The sight is incredible. The artificial light atlas clearly shows that the Milky Way is hidden today from the eyes of almost a third of the planet’s population. Some 60 percent of Europeans and 80 percent of Americans cannot see it because of the light pollution.

This interest in light pollution in the context of star-gazing and seeing the Milky Way is based on historic reasons. Astronomers were the first to point out the problem of light pollution because they found it more and more difficult to observe the stars, says Portnov. This poetic and romantic call from astronomers moved quickly to much more practical and critical tracks.

Portnov says giving up the night in favor of economic profits has cost us dearly, even now. “Excess illumination has a direct and proven link to a dramatic rise in [the incidence of] breast cancer and prostate cancer, obesity, sleep disorders – and this is just the tip of the iceberg of the price humanity will pay for giving up on the night. When you look at the atlas of artificial illumination, you understand easily where the most serious problems are – in all industrialized nations. When we disconnect ourselves from nature, we pay a price for it.”

Prof. Abraham Haim.Credit: Moshe Gilad

Prof. Abraham Haim of the Natural Resources and Environmental Management Department at the University of Haifa has been studying light pollution for years. He is very outspoken about its health effects and especially about the influence of light-emitting diode, or LED lighting, which he views as causing major damage. “We don’t understand that as animals we developed in a world that has periodicity of light and darkness. For an animal this is the most important signal. Short and long days are the basis for seasonality. That is how birds know when to migrate, for example.”

For example, over-illumination depresses the production of melatonin, the “hormone of darkness,” whose levels in the bloodstream change with a daily periodicity and are a signal for the body about sleep times and the functioning of other biological systems, Haim explains. “The result will be a rise in morbidity from cancer and a steep rise in vision problems because of damage to retina. The damage stems from the powerful intensity of the illumination. The problem is that we prefer to take problematic technology and improve it, instead of using good technology and making it more efficient.”

Haim also speaks out strongly against a number of the accepted ideas about artificial lighting. “We think that road lights reduce traffic accidents. That is not true. There are no data that point to that,” he says.

“In many cases it is the opposite – you light up the road and then drivers drive faster and carelessly. It’s better for intercity roads to be darker. Another issue is personal security: Are we better protected in a lit place from attack than in a dark place? This, too, has no support from scientific data,” says Haim.

“In many cases the opposite has been proved: The attackers prefer a lit place in which they can see the victim, to decide if it is worth attacking him. All these are excuses for wasteful and superfluous excessive lighting that causes damage.”