Losing the Night

In 1994, the Northridge Earthquake knocked power out in Los Angeles, California. Since that time, a regularly-repeated internet-based story is that residents called 9-1-1 in a panic in the pre-dawn hours when they went outside after the earthquake and, for the first time, saw the trail of the Milky Way in the sky — they freaked because they had no idea what the strange lights in the skies actually were. They had never seen stars like that before.

The story is slightly apocryphal. Residents weren't in a panic and they didn't call 9-1-1. However, several uncertain people did call the Griffith Observatory to check on what they were seeing due to the blackout after the earthquake.

The bigger picture remains true in both stories: the loss of artificial lighting during a power outage introduced many residents of Los Angeles to the wonder of the Milky Way, a phenomenon they had never seen before because of one simple but terrible explanation: light pollution.

For billions of years, life on this planet has relied on the predictable rhythm of day and night. It’s been encoded in the DNA of Earth's plants and animals. Humans have shattered this cycle by lighting up the night.

Plants and animals depend on Earth’s daily pattern of light and dark to govern life-sustaining behaviors such as reproduction, sustenance, rest, and defense against predators.

Scientific evidence suggests that artificial light at night has negative and indeed deadly effects on many creatures, including birds, amphibians, insects, mammals, and plants.

Humans — mammals ourselves — also evolved to the cycle of day and night. The proliferation of artificial light at night means most of us no longer experience the truly dark nights our bodies still need.

Many studies have shown that exposure to artificial light at night negatively affects human health, including increased risk for:

• Sleep disorders
• Depression
• Obesity
• Diabetes
• Heart disease
• Cancer

According to the  American Medical Association , “It is estimated that white LED lamps have five times greater impact on circadian sleep rhythms than conventional street lamps. Recent large surveys found that brighter residential nighttime lighting is associated with reduced sleep times, dissatisfaction with sleep quality, excessive sleepiness, impaired daytime functioning and obesity.”

According to  a 2023 paper by eight physicians and researchers published in GeroScience  (the journal of the American Aging Association) “there is an increasing number of research underlining the complexity of the correlation between light pollution and Alzheimer’s disease; however, additional studies to enhance the key tenets are required for a better understanding of this relationship.”

Until very recently in human history, our ancestors experienced a sky brimming with stars — a night sky that inspired science, religion, philosophy, art, and literature, including some of Shakespeare’s most famous sonnets.

The natural night sky is our common and universal heritage, yet it’s rapidly becoming unknown to the newest generations.

Van Gogh painted his famous “Starry Night” in Saint Rémy, France, in 1889. Now, the Milky Way can no longer be seen from there. If he were alive today, would he still be inspired to paint “Starry Night”?

Experiencing the night sky provides perspective and inspiration, and leads us to reflect on our humanity and place in the universe. The history of scientific discovery and even human curiosity itself is indebted to the natural night sky.

The New World Atlas of Artificial Night Sky Brightness,  presented in Science Advances in 2016 , shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans. Moreover, 23% of the world’s land surfaces between 75°N and 60°S, 88% of Europe, and almost half of the United States experience light-polluted nights.

Many municipalities around the world have begun replacing their old sodium vapor lights to LED (light-emitting diode) lights, because the LEDs light up the night while consuming less energy.

One major problem, it turns out, is that the vast majority of municipal LEDs in street lamps and other outdoor lights are bright white, or even slightly blue--which has a major disruption to night vision and circadian rhythms. The old sodium vapor were at least a warmer color.

The two images below are of the Italian city of Milan, taken from aboard the International Space Station in 2012 (left) and 2015 (right). The city center became noticeably more blue in the interim after the Milan converted much of its municipally-owned lighting from low-pressure sodium vapor lamps to white LED lamps.

Consider these facts:

• 80% of Americans can no longer see the Milky Way
• Astronomy and astrophotography blogs and discussion groups are regularly debating the apparent decline in those hobbies
• Writers have noted the decrease in numbers of youth who venture out (or who can venture out) at night to see the night sky
• Fewer people can name or navigate by stars
• People sleep surrounded by an ambient artificial light that harms their health

Seek out dark sky places! They do still exist.

The  International Dark Sky Places (IDSP)  program from  DarkSky International  certifies communities, parks, and protected areas around the world that preserve and protect dark sites through responsible lighting policies and public education.

The group has certified more than 200 Places since Flagstaff, Arizona, was named the first International Dark Sky City in 2001. There are now over 160,000 square kilometers of protected land and night skies in 22 countries on 6 continents, and the list grows every year as new places achieve certification.

In the U.S., 136 Places have received some sort of designation. See how close you are to one:

What about all the people who aren't within easy distance of a natural dark sky?

What actions can you take to improve lighting in your community?

What policies can you advocate for?

What art can you make?