Artificial skyglow: The dark sky is a natural resource, and too much light is polluting it

Source: The post is based on the article “The dark sky is a natural resource, and too much light is polluting it” published in The Hindu on 24th January 2023.

What is the News?

According to a study, light pollution is growing rapidly and in some places, the number of stars visible to the naked eye in the night sky is being reduced by more than half in less than 20 years.

About the study on the artificial skyglow

The human eye should be able to perceive several thousand stars on a clear, dark night. But the growing artificial brightness at night has robbed people of the night-time starry view.

This is because as the sky brightens up with artificial light, the fainter objects are not visible to the unaided human eye and disappear. 

According to the study, over the past ten years, the sky has brightened by 9.6%. This is much more than the around 2% per annual global increase measured by satellites.

Due to this, the stars are disappearing right in front of our eyes at a startling rate and a large number of stars that were once visible to us are no longer visible to us.

The change is so fast that a child who was born in a place that had 250 visible stars would only be able to see about 100 stars by the time they turn 18.

What is the situation in India on Artificial Skyglow?

A 2016 study reported that 19.5% of India’s population — the lowest fraction among G20 countries — experiences a level of skyglow that would at least keep the Milky Way galaxy out of sight and at most render dark adaptation for human eyes impossible. 

What are the consequences of this artificial glow?

Numerous studies have found that artificial light at night affects both people and wildlife in significant ways:

According to a 2003 report, lit beaches deter sea turtles from coming ashore to nest. A 2006 review found that skyglow keeps trees from sensing seasonal variations. 

A 2017 study found that young burrow-nesting seabirds don’t take flight unless the nesting site becomes dark. 

A 2019 study reported that clownfish eggs don’t hatch when exposed to artificial light at night, killing the offspring. 

A 2020 study noted that skyglow interferes with multiple aspects of insect life and allows insect predators to hunt for longer.

A 2020 study found that disrupting the circadian rhythm, artificial light at night can hamper the production of melatonin, an influential hormone in the human body which affects sleep, moods and cognition.