Astronomer Carl Sagan said that there are more stars in the universe than grains of sand on earth.
It is estimated that there are more than 100 billion stars in the Milky Way galaxy. Although the number of stars is the limit that we can see with the naked eye from Earth, this number decreases completely due to light contamination.
“We can see about 2,500 stars with the naked eye in one night, and we can see about 125 at best in Sydney,” says Kirsten Banks, astrophysicist, proud Wiradjuri woman, and PhD candidate at UNSW.
In fact, in a recent study published in Science, data collected by educated citizens around the world revealed that light pollution has increased to the equivalent of doubling the brightness of the sky every eight years.
This latest research continues to reveal just how much darkness is being lost to the night skies. Not being able to look up and see the stars will have a significant cultural impact, but we can all take steps to reduce the effect of light pollution.
What makes it shine?
Artificial lighting streaming into the sky causes what is known as “glowing,” a type of light pollution that makes it difficult for people to see the stars.
“The luminous glow is an extra light that is not useful to see when you are walking in the dark, for example. And it’s that light that’s diffused and sprinkled into the sky just like the fainter lights that stars usually are,” said Ms. Banks.
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This latest study involved more than 51,000 citizen scientists observing naked-eye star visibility, showing the change in global sky brightness over an 11-year period, from 2011 to 2012.
The data showed that the number of visible stars decreases by an amount that can be explained by the brightness of the sky by 7-10% per year.
This study was carried out on a global scale, but about 68% of the observations originated from North America and Europe, with one time in Australia in 2020 the campaign was collected in Asia, Africa and America del Sur.
Although most of the data is collected elsewhere, Ms Banks says light pollution is still a problem in Australia. “In Sydney we experience that the light is almost the same as the moon. And this means that if you are somewhere without a bright spot and a full moon, you have the same kind of visibility as the night sky. than in Sydney.
You don’t need any special devices or equipment to look at the stars.
“I think it’s important to be able to look at all the stars because it’s one of the most transparent sciences,” says Ms Banks. “All you have to do is look and you can see, by looking at astronomy you are able to go to the night sky. And when we remove that light pollution, we get all the knowledge about people.”
Many different cultures around the world have a rich history and connection with the stars and the night sky.
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In Australia alone there are more than 250 indigenous groups who have understood and used the stars for the last 65,000 years, and their knowledge is still practiced today, says Ms Banks.
Ms Banks talks about Gugurmin, the celestial emu, a star based in the hazy space around the Milky Way, in her 2019 TEDx Talk on the Great History of Australian Aboriginal Astronomy.
“The night sky is very important to indigenous peoples.
We are losing culture because of the stars we see in these bright cities. All these stars have cultural significance in stories and readings. And some of them we can no longer see. So through that and of course all the other effects of colonialism, we lost all those stories. »
Reverse Light Grow Impact
Unlike many other types of pollution, light pollution is reversible, and there are levels of deep-sky darkness to repair.
“There are many ways to reduce the amount of light pollution we emit into the sky,” says Ms Banks.
“A good example is the creation of very directional streetlights. So when you walk, you can see the street lights, which are just big lights shining in every direction. But in reality, we only need light to illuminate the way you walk in what is really available. So we can change the distribution of lights of ours to make more progress where we want the light to be.
As we use the direction and brightness of the lights, we can also change the color to a more amber/orange tone that reduces the glare of the light, says Banks.
While these have been taken into account, much remains to be done. In recent years, awareness of light pollution has led some policy makers to introduce control measures.
“These plans have already been discovered in the Coonabarabran area,” says Ms Banks. “There are very strict regulations for all types of lights and they have certain regulations to preserve the night sky in this area for close observation.”
As Ms. Banks explains, everyone can play a role. “One way to get people involved is to turn off only the lights that aren’t necessary, like bright bulbs in the hallway or yard.
“A simple solution to this that people can take every day.”