Our loss of the night sky

For billions of years, all life has evolved, survived and thrived through the steady rhythm of Earth’s day and night.

Humans have disrupted this cycle by lighting up the night during the past 200 years, altering the natural light levels. Most of us no longer experience truly dark nights.  

This disruption, called light pollution, is creating negative impacts on wildlife, ecosystems and human health. Light pollution wastes money and energy, contributing to climate change and the loss of our night sky heritage.  

Light pollution is the creation of excess and unnecessarily artificial light. 

Cities account for most of this, spilling wasted light up into the air instead of down at the ground. Sources include streetlights, lit up empty parking lots and sport fields, houses and apartments, landscaping and mood lighting, and advertising billboards that are 10 times brighter at night.

The international Dark-Sky Association is the globally recognised authority on light pollution issues and night sky conservancy. They estimate that at least 30 per cent of all outdoor lighting in the United States alone is wasted, costing up to $3.3 billion and releasing 21 million tons of carbon dioxide per year.

They further state that “there is no clear scientific evidence that increased outdoor lighting keeps you safe and deters crimes. Rather than making you safer, glare from floodlights increases shadows and doesn’t let the human eye adjust to see what’s there”.

Once the sun descends for the night and we are exposed to low light, our bodies naturally release melatonin. Light pollution curbs melatonin production in humans, disrupting our natural circadian rhythms.  

Many studies have shown that artificial light at night increases our risk of sleep disorders, depression, obesity, diabetes, heart disease and cancer.  

Plants and animals depend on Earth’s daily cycle of light and dark to govern life-sustaining behaviours such as reproduction, nourishment, sleep, and protection from predators.

Birds that migrate or hunt at night navigate by moonlight and starlight and due to artificial light, they can wander off course. Every year millions of birds die colliding with needlessly illuminated buildings and towers. 

Migratory birds depend on cues from properly timed seasonal schedules. Artificial lights can cause them to migrate too early or too late and miss ideal climate conditions for nesting, foraging, and other behaviours.

Declining insect populations, fatally drawn to artificial light, negatively impact all species that rely on insects for food or pollination.

Our ancestors experienced a sky brimming with stars – a sky that inspired exploration, story, science, religion, philosophy and art. The natural sky is our common universal heritage, yet it’s rapidly becoming unknown to the newest generations.

In Astronomy: Sky Country, the connections between Aboriginal practices and the behaviour of the stars are explored, along with how to sustain the dark skies and the information they hold into the future. 

To find out how to protect the night sky visit www.darksky.org •