One-third of the world cannot see the Milky Way – why that matters

Story highlights

Eighty-three percent of the world's population lives under a haze of artificial light

Extremely bright night skies can cause ecological problems, health issues and wasteful spending

CNN  — 

If you look up at the evening sky, there’s a good chance you will not be able to see what your grandmother saw when she was a little girl.

That’s because we’re enshrouded in an artificial haze of light that is blocking the night sky, a phenomenon scientists call light pollution.

Scientists believe one-third of humanity cannot view the Milky Way — this includes 80% of Americans and 60% of Europeans because city lights are creating fogs of light pollution, according to a new study that published Friday in the journal of Science Advances.

The Milky Way sparkles over the Grand Canyon in Arizona.

An international team of scientists created a world atlas of artificial sky luminance that details how light pollution is permeating our planet. This light is obscuring our vision of the stars, celestial events and the Milky Way — the galaxy that contains our solar system.

Although there are a few patches of pristine dark sky still left in the world, 83% of the world’s population and more than 99% of the U.S. and European populations live under the bright glow of light pollution.

“This is a huge cultural loss with unforeseeable consequences in the future generations,” scientist Fabio Falchi, one of the authors of the study, says. “Pristine night skies are a precious merchandise.”

The most light-polluted country in the world is Singapore, the study finds.

“The entire population lives under skies so bright that the eye cannot fully dark-adapt to night vision,” according to the study. This means people living in the country never have the chance to experience true darkness.

Here are other countries where more than half of their inhabitants are living under extremely bright skies, according to researchers. (The numbers denote the percentage of the population affected by light pollution.)

Kuwait (98%)

Qatar (97%)

United Arab Emirates (93%)

Saudi Arabia (83%)

South Korea (66%)

Israel (61%)

Argentina (58%)

Libya (53%)

Trinidad and Tobago (50%)

The countries with populations least affected by light pollution include Chad, Central African Republic, and Madagascar. More than three-quarters of people in these countries are living under pristine night sky conditions.

The dangers of too much light

The findings shows that light pollution is a global issue, and many countries are affected by a fog of artificial light. But light pollution doesn’t just obscure our view of space.

This over-saturation can impact our culture, cause global ecological problems, pose public health issues and create wasteful energy spending, the researchers warn.

For instance, artificial light has a direct effect on human physiology and behavior. For instance, it can alter our circadian rhythm and affect production of some of our hormones, a 2007 medical study found. It can also disrupt our sleep cycle by suppressing melatonin creation and increasing cortisol levels — a hormone that is linked to stress.

Researchers found that people living in urban environments were the most affected by light pollution, but what is troubling is that the glow of city lights is creeping into unpopulated areas too.

This is important because artificial lights can negatively affect wildlife. For example, streetlights near shorelines can cause baby turtles who have just hatched to become disoriented and wander inland instead of into the ocean, causing them to die because of dehydration or exposure to predators, according to research by the Sea Turtle Conservancy.

So why has our world been overtaken by light pollution?

“Light pollution is also a consequence of the belief that artificial light increases safety on roads and prevents crimes, but this belief is not based on scientific evidence,” the study states.

Saving the darkest skies

“It is always surprising to find out how in few decades of lighting growth we enveloped most of us in a light curtain that hide the view of the greatest wonder of nature, the universe itself,” Falchi says.

In less than a 100 years, artificial lights have transformed the sky. Millions of children will never experience the Milky Way, according to the International Dark-Sky Association (IDA), an organization combating light pollution.

Light pollution “robs us of the opportunity to experience the wonder of a natural night sky,” according to the organization’s site.

In order to persevere the world’s limited patches of pristine night sky, IDA launched the International Dark Sky Places conservation program in 2001, which encourages communities to protect dark sites.

Some of these International Dark Sky Sanctuaries, which are the most remote and darkest places in the world, include the Associated Universities for Research in Astronomy Observatory, which operates in the Elqui Valley of northern Chile and the Cosmic Campground, a site located in the Gila National Forest of western New Mexico.

The hazards of light pollution are slowly starting to be taken seriously by scientists, the study says.

There are ways to combat the haze of artificial light from overtaking our night skies. Researchers suggest communities experiment with new technology that limits the spread of light pollution, use minimum light for tasks, encourage the practice of shutting lights off when areas are not being used and limit the use of “blue” lights which can affect circadian rhythms and even vision.

The beauty of a pristine night sky can also influence people, Falchi says.

“I was pushed to study physics, ultimately, by the fact that I had the possibility 30 years ago to see a fairly good sky where I lived. Now, in the same place, the Milky Way is totally lost,” he says.