Blinded by the light: how skyglow pollution is separating us from the stars
Light infrastructure has expanded alongside population growth but it’s not only star gazing in jeopardy – cultures, wildlife, science and human health are all threatened
On a clear dark Queensland night in 1997, Brendan Downs was staring up into the cosmos alongside a band of other amateur astronomers. He trained his telescope on a galaxy called NGC 6769, floating more than 169m light years away, and took a picture.
“I had a reference image that I had in a book at the time, and I visually compared the object on the screen to the object in the book,” he says. “I counted the number of stars I was looking at.”
One, two, three, four, five …
One, two, three, four, five, six …
“I should be able to count easily,” he says. “My heart rate goes up. I went to a couple of friends and, very quickly, everyone could see there was an extra star in the image I took.”
He had captured the explosion of a star, a supernova. The discovery – shared with a New Zealand astronomer who photographed the same blast of light that night – was registered with the International Astronomical Union under the name 1997de.
Downs went on to discover a second supernova, 2010dc, in his back yard Thunderchild Observatory in Ipswich, west of Brisbane, and has helped to confirm countless others.
In back yard observatories around the world, amateur astronomers’ discoveries are contributing valuable data to scientists. 1997de formed part of a dataset that helped Brian Schmidt’s team of scientists researching the origin of the universe, for which they went on to win a Nobel prize.
Yet one threat to astronomy is slowly curtaining the view beyond our atmosphere. It’s all over the world, it’s in your street and it glows from every bulb: light pollution.
It’s not only star gazing that’s in jeopardy. Culture, wildlife and other scientific advancements are being threatened by mass light infrastructure that is costing cities billions of dollars a year as it expands alongside exponential population growth.
Some researchers call light pollution cultural genocide. Generations of complex knowledge systems, built by Indigenous Australians and Torres Strait Islanders upon a once-clear view of the Milky Way, are being lost.
In the natural world, the mountain pygmy possum, a marsupial native to Australia, is critically endangered. Its main food source, the bogong moth, is being affected by artificial outdoor lighting messing with its migration patterns. Sea turtles are exhibiting erratic nesting and migration behaviours due to lights blasting from new coastal developments.
So how bright does our future look under a blanket of light?
“If you go to Mount Coot-tha, basically the highest point in Brisbane, every streetlight you can see from up there is a waste of energy,” Downs says. “Why is light going up and being wasted into the atmosphere? There’s no need for it.”
Around the world, one in three people can’t see the Milky Way at night because their skies are excessively illuminated. Four in five people live in towns and cities that emit enough light to limit their view of the stars. In Europe, that figure soars to 99%.
Blame skyglow – the unnecessary illumination of the sky above, and surrounding, an urban area. It’s easy to see it if you travel an hour from a city, turn around, then look back towards its centre.
James Barclay was forced to move his astro-tourism business Kingaroy Observatory to a new site near the airport after the Queensland town’s outdoor lighting grew with the population. “Light pollution is taking away one’s God-given right to see a dark, starry sky,” he says.
Artificial lights at night cause skyglow in two ways: spill and glare. Light spills from a bulb when it trespasses beyond the area intended to be lit, while glare is a visual sensation caused by excessive brightness.
Streetlights contribute hugely to this skyglow and have been causing astronomers anxiety for decades.
The switch to LED
But the solution isn’t a simple switch to more energy-efficient technologies.
Queensland now relies heavily on mercury-vapour lamps, known as HPMVs. Last year it had an estimated 176,000 HPMV streetlights – more than the total in Victoria, NSW, Tasmania, Northern Territory and the Australian Capital Territory combined.
HPMVs are expensive and inefficient compared with an alternative technology – LED (light emitting diodes) – and the mercury in them can harm the environment and human health. Australia plans to phase out all HPMV lamps as early as 2026 under the Minamata convention on mercury, opting for LED street lighting in its place.
But councils are choosing a type of LED that fails to meet standards designed by the Australasian Dark Sky Association (Adsa) to prevent harm to the environment and ourselves. They were drawn up in accordance with legislative requirements to protect ecosystems, wildlife, human health and comfort, and views of the night sky.
To satisfy the voluntary Adsa standards, local authorities would have to roll out lamps that eliminate upwards light waste and emit light at or less than 3,000 correlated colour temperature (CCT) – a measure of how yellow or blue the light appears.
The Queensland government-owned energy company that owns much of greater Brisbane’s street lighting, Energex, is switching to cheaper LEDs that emit a bluer 4,000CCT, excluding them from the Adsa standards.
Dr Ken Wishaw, an Adsa co-founder, says cheap technologies present a major threat to the environment.
“From the perspective of efficacy, health effects, effects on other species, and skyglow, LED lighting with a CCT of not greater than 3,000 should be used,” Wishaw says.
An Energex spokesperson said while it considered the impacts of skyglow and light pollution, the majority of councils opted for a 4,000CCT design “due to the better performance and efficiency”.
They said the company had “adopted zero-degree upcast luminaires with a full cut off lens to minimise skyglow and lighting pollution”.
Blue-wavelength light typically emitted by high CCT LEDs may not be damaging to road users given a short exposure time, but impacts for wildlife and long-term exposure for humans are far more problematic.
Studies show that blue light may disrupt sleep patterns, with some suggesting links to mental illness, cancer, cardiovascular disease and other medical disorders.
In the Sunshine Coast hinterland town of Maleny, 100km north of Brisbane, more than 1,000 local people signed a petition to protect the last location in coastal south-east Queensland not heavily polluted by light. The petition calls for streetlights that comply with Australian government national light pollution guidelines and the Adsa criteria.
Local activists and project leaders are in discussions with council and government departments to push for widespread changes.
And, while the Sunshine Coast council has been commended for its commitment to Adsa conventions in its urban lighting master plan – part of its vision of being the most sustainable region in Australia – the rest of the country is yet to catch up.
Campaigners say global united action on light sustainability guidelines is essential if humans are to manage our use of artificial light sources.
Into the dark
In deep space, Downs’ first discovery – 1997de – was completely obliterated when it exploded hundreds of millions of years ago. Though the actual supernova would have lasted a matter of seconds, it shone bright enough to be seen from Earth for about a month before it slipped back into the dark expanse of the cosmos.
Our vision of the stars is always dated. The further you look into space, the further back in time you see.
How many stars can you see?