Experiencing the dark night sky produces positive emotions and a sense of awe in many people. But researchers say artificial light is a substantial, global threat to our natural dark skies, and we risk losing sight of the stars.
You don’t need to be a stargazer or astronomer to care about light pollution. As well as obscuring the night sky, excessive or inappropriate outdoor artificial light affects human health and wildlife.
Why is light pollution bad for stargazing?
In stargazing, the stellar magnitude scale measures the brightness of objects. The higher the magnitude number something has, be it a star, a nebula, or something else, the fainter it is. The Full Moon’s apparent magnitude is about −11, and if you spot the International Space Station, it might be around magnitude -3. The brightest stars in the night sky have a magnitude of about 1, the fainter ones around magnitude 6.
Under the truly dark skies, the kind you find in astrotourism towns or dark-sky preserves, you can see stars up to around magnitude six. The most significant negative impact of light pollution is most apparent in cities and towns, with the way sky glow washes out the night sky stars. In these conditions, the only objects visible in the night sky are the Moon, the planets, bright satellites, and the brightest stars.
As light pollution worsens and cities continue sprawling outwards, spreading their glow with them, astronomy becomes more difficult. The problem isn’t only from the sky glow of cities, towns, and mines, either.
Less than 70 years ago, when the USSR put Sputnik 1 into Earth’s orbit, it was our planet’s first artificial satellite. More than 3,000 active satellites are orbiting Earth today, and the newest satellite ‘mega-constellations’ are putting tens of thousands more into the night sky.
How does artificial light affect people?
A cultural connection between humanity and the night sky goes back thousands of years. Astronomers Duane Hamacher and Krystal de Napoli highlight that “erasure of the night sky acts to erase Indigenous connection to the stars, acting as a form of ongoing cultural and ecological genocide.”
Whitening the Sky: light pollution as a form of cultural genocide describes the impact of growing light pollution on this ancient knowledge. It demonstrates how important it is for the people of stars-based Indigenous traditions and knowledge systems worldwide to observe and interpret stellar positions for their daily life and cultural continuity.
Researchers Christopher Barnes and Holli-Anne Passmore say that individuals who feel more connected to the night sky report higher levels of overall well-being, with higher scores for positive mental health and happiness. Night sky connectedness is important, they say, because a connection to the night sky can help increase a person’s overall connection to nature, helping maintain a sustainable relationship with the environment.
Excess light at night lowers melatonin, the brain chemical that controls your sleep-wake cycle. Mess with that, and you could get sleep deprivation, tiredness, headaches, stress, anxiety, and more. Some studies suggest that artificial light at night could worsen conditions like dementia and Alzheimer’s.
How does light pollution hurt wildlife?
WA’s Department of Biodiversity, Conservation and Attractions (DBCA) ‘s National Light Pollution Guidelines for Wildlife explains that artificial light can stall the recovery of threatened species and interfere with a migratory species’ ability to undertake migrations integral to its life cycle.
Consider sea turtles. Collectively, they’re over 100 million years old and could become extinct in our lifetime, partly because of the effects of light pollution. CSIRO, Australia’s national research agency, says light pollution from coastal development, including ports and marinas or oil and gas infrastructure, poses risks to our native sea turtles. Turtle hatchlings can get disorientated by artificial light and light glow, mistakenly heading inland instead of towards the ocean.
The Australian Government’s Recovery Plan for Marine Turtles in Australia says turtles nesting on beaches in Western Australia are “at highest risk from the effects of light pollution.” Some migrate vast distances between where they feed and where they nest, favouring specific places in WA such as Barrow Island, Mundabullangana Station, Delambre Island, and Thevanard Island.
These nesting sites are already threatened by various things, and brightly lit beaches can put off adult turtles from nesting. When turtles don’t necessarily nest every year, the odds aren’t in their favour.
Will you help reduce light pollution?
Carol Redford, CEO of Astrotourism WA, is one of 2,000 Dark Sky Advocates worldwide, striving to protect the night sky using education, advocacy, and community science. Carol works with 18 regional local governments to develop dark sky tourism. Together, they’re changing light management practices across WA.
“Shielding light is a great way to reduce light going up into the night sky, so simply putting a shield around the light, you’ll notice a huge difference,” Carol says.
In WA, the state-owned Western Power is responsible for building, maintaining and operating our electricity network. This includes operating and maintaining around 280,000 streetlights on behalf of local governments across the South-West.
Since 2019, Western Power has been trialling new LED streetlights, which use up to 80% less energy and last longer. While the LED lights are brighter “and whiter” than previous street lighting, Western Power says that because the light diffuses and distributes more precisely, LEDs reduce glare and light only targeted areas.
However, not all LEDs are created equal. While LED lights are more energy-efficient, they can produce a higher level of blue light. This is the light that has a negative impact on wildlife, diminishes our view of the night sky, and affects human health. When selecting an LED, choose a warmer coloured light and this will greatly benefit the night time environment.
We can all do our part to reduce and limit light pollution. DarkSky International offers the above five principles for responsible outdoor lighting, and their Home Lighting Assessment will help you identify problem lighting and solutions at home that can reduce light pollution.
Although Australia has the lowest proportion of land area affected by light pollution among the G20 countries, we have one of the highest rates of light pollution per person,” Carol says.
“I’d like to challenge Western Australia to become world leaders in lighting management and the reduction of light pollution. Then one day, Perth could reinvent itself as the City of Starlight.”
Jay Chesters is a freelance journalist, feature writer, and award-winning author. With a particular passion for stargazing and astronomy, Jay enjoys any opportunity to share stories or pass on what they know.
Jay Chesters
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