Comparison showing the effects of light pollution on viewing the sky at night. The southern sky, featuring Sagittarius and Scorpius. Top image shows the sky from Leamington, Utah (population 217). Bottom image shows Orem, Utah (metropolitan area with a population of around 400,000).
Credit: Jeremy Stanley/Wikimedia
SYDNEY: Light pollution has caused one-fifth of the world's population – mostly in mainland Europe, Britain and the U.S. – to lose their ability to see the Milky Way in the night sky.
"The arc of the Milky Way seen from a truly dark location is part of our planet's natural heritage," said Connie Walker, and astronomer from the U.S. National Optical Astronomy Observatory in Tucson, Arizona.
Yet "more than one fifth of the world population, two thirds of the U.S. population and one half of the European Union population have already lost naked eye visibility of the Milky Way."
Star-free night
The phenomenon, caused by the reflection of manmade light by the Earth's atmosphere, impacts astronomical research and can even affect human health, warned Walker, who will present her research on Wednesday at a meeting of the American Astronomical Society in Pasadena, California.
The effects of light pollution on human health can be as mild as the disruption of the circadian rhythm leading to problems sleeping, but it can also be serious, she said.
One study of 147 Israeli communities, published in 2008 in the journal Chronobiology International, found some evidence for an increased risk of breast cancer for women living in areas with the most light pollution. This is thought to be due to unnatural light at night affecting levels of hormones such as melatonin and estrogen.
Light pollution comes in a variety of forms such as 'over illumination', 'light trespass' and 'sky glow' – the orange glow that hangs over cities and is produced by upwards directed light.
Walker's research has found that cities using light fixtures that direct just 3% of their light upwards can almost double the sky glow experienced by astronomical observatories 100 km away. "Allowing 10% direct uplight increases this figure to 570%," said Walker, who is chair of the U.S. Dark Skies Working Group, part of the Dark Skies Awareness program, a global citizen science effort to raise awareness of light pollution.
GLOBE at night
"The point of raising awareness of light pollution is that it touches many areas of people's lives, from simply not being able to see the natural heritage of a starry night sky to affecting... the habits of animals, energy consumption, economic resources, and astronomical research," she said.
One project called GLOBE at Night, teaches members of the public "to record the brightness of the night sky by matching its appearance toward the constellation Orion with star maps of progressively fainter stars," said Walker.
These measurements are then submitted online and are used to create global maps of levels of light pollution. Over the last four years, the annual, two-week long GLOBE at Night events have resulted in 35,000 measurements contributed from over 100 countries.
Data from this project and others allowed Walker to estimate how much of the world's population is still able to see the Milky Way on a clear night.
One fifth of us have lost sight of the Milky Way?
So we cannot see the Milky Way!
Perhaps it is time that we should be focusing attention on the harm done by the 24 hour day? We should be concerned about how sustainable is our collective future? Medical evidence for this harm, which is being caused to human health, by light at night, is mounting. We are seeing melatonin suppression, caused by too much light at night, reducing our ability to fight cancer.
Children, sleep deprived, are hypertensive, hyperactive and likely to succumb to obesity. Emergency workers, like doctors and nurses, working overly long shifts, risk making poor decisions. Danish women have already been awarded compensation for shift work “causing” breast cancer.
The harm to both flora and fauna in the 24 hour day is also increasing. It denies life its natural circadian rhythm, which apparently regulates ALL life forms on Earth. It is not just nocturnal creatures which are suffering a decline. So too are sparrows! Light at night sucks insects to their deaths. Sparrow chicks need insects – without them the chicks just die.
So then we have light at night, insect decline, potential widespread species decline - all of which go hand in hand with the 24 hour day! We have lived on Earth with many other species for millennia. We have only had the 24 hour day for a few decades.
Light pollution, making it impossible for anyone to see the Milky Way, will be the least of our problems.
light pollution might not be all that much to worry about
i don't think there's been too many cockroaches and other insects dying from light pollution, and last I checked, there weren't any dead birds in the yard either, although I did see a flattened squirrel. Perhaps if the street had more light reflected by the sky he'ld had a chance.
Light Pollution, making it impossible for anyone to see.....
I don't understand how you could say that light pollution is the least of our worries....
If we didn't have light pollution, it wouldn't be causing the death of birds, bats and helping to cause cancer in human beings period.
I weep...
Needless to say, I'm not too terribly old at a blistering age of 33, but at the same time I'm old enough to live next to (what is now) a major metropolis... and I miss the night sky. I can pick out Orion, the big dipper, Saturn, Jupiter and the Moon.
I can only imagine what this light pollution is doing to the natural rythm's that helped to sustaind our species and our planet for so long :(
I don't know the statiscal research on what it does to the Danish women or how it affects the tree frogs in Brazil, but I know it puts a hole in my heart every time I can't look up and see the universe as it is instead of a few twinkling stars. Generations are being deprived and are turning to all things terra rather than looking up and being fascinated by the heavens.
That's my opinion atleast... for what it's worth.
- Robert
Phoenix, AZ, USA
Agreed.
Amen to that Robert.
I can remember some decade plus ago, when I was barely a teen, my family spent a great deal of time at lake Ouachita in central Arkansas. Camping on the islands there, you could see a brilliant night sky. Today, going to the Vista that overlooks the lake, at least a quarter of that sky is blurred away and I have to unfocus my eyes in order to see the shape of the Milky Way. There is still much to see it that sky, but you can clearly see what the nearby city's progress has done to it in such a short period of time.
Honestly, it's damned near heart breaking.
I'm determined to take my next vacation to one of those Dark Sky parks though!
-Arkansan
No vermin?! OH NO!
My goodness! Now we won't have disease spreading creatures or useless animals taking up our space! Perhaps if we just undo all of mankind's creations we could allow the already massive reproduction of vermin to multiply more effectively!
Oh let's also allow more night time criminal activity while we're at it! The police can't catch what they can't see in the night!
Criminality
Light pollution reduces biodiversity by killing insects and starving out the higher order consumers such as bats that depend on them. Reduce the numbers of bats and other insectivores and your mosquito population will increase substantially; and along with it the increased risk of insect transmitted diseases.
The linkage between lighting and criminality is a fallacy encouraged by the lighting industry and municipal lighting departments to promote their products and safeguard their own jobs. Lighting does not reduce crime. In fact most crime occurs in daylight, ergo criminals need light. Lighting encourages people to behave more at night as they would during the day, so it comes as no surprise that our most crime infested areas are also the most intensively lit. In addition, it has been documented that criminality drops almost to zero during power failures. Exterior lighting should only be applied on a needs must basis, when needed, where needed, and in the correct amounts.
1/5 of the world population
1/5 of the world population can't see the Milky Way, but 1/5 of the work population (not) coincidentally has access to adequate, refined water, plentiful food, abundant forms of transportation, 24/7 access to resources, seemingly unlimited amounts of electricity/heat, and basically anything we could possibly want at our fingertips.
While in theory you can have all these things and still see the Milky Way, the way things worked out in practice (with oil, pollution etc), it was either one (clear skies) or the other (everything else).
There's a price to pay for everything. This is one many of us are willing to pay.
Chloé Simon, from Tendances de mode
Sic transit
One of the best presents I was given as a child was a build it yourself 4 inch reflecting telescope. In those far off days (circa 1955)one could see a good night sky even from a housing estate outside a medium sized town in Surrey. Much later in my 40s I joined the local astronomy group here, which was called ASH (Astronomical Society of Haringey in London UK). Following a childhood wish I bought an 8 inch reflecting telescope. At first I could see a reasonable number of stars, although not the milky way on a good night and I worked through some of the more obvious Messier objects as well as learning the constellations of the Northern Sky. Gradually the night sky became more and more orange until you could read a newspaper by it even in the middle of Hampstead Heath. By the time I could only barely make out the plough I gave up and my telescope sits in the garden, its mirror in need of resilvering, a more or less uneless memento of a former hobby. The last time I pointed it at an object was the sun for the transit of venus, when cutting down the light was the main requirement. Sic transit venus!
Astronomers were talking about light pollution in the 1980s and it is a lost cause in the UK. Amateurs will have to turn to radio astronomy if they live on this crowded island. Actually those computer programmes that show you the night sky as it would be if you could see it are about as close as we get now.
A charming creature that has been almost lost due to light pollution in the UK is the glow worm. The males are confused by street lighting and cannot find the famales who used to attract them with their glowing tails on June nights.
Sports lighting does worse than just blotting out the stars
Sports lighting typically uses metal halide lamps to give white light. Exposure to this blue-rich light at night can interfere with circadian rhythms and reduce the amount of melatonin that is produced by the pineal gland. Both of these effects have been proposed as explanations of why the rates of breast cancer and prostate cancer are reliably greater in towns and countries with brighter outdoor lighting. Most people will go through their life without getting such cancers even when they have repeated exposures to sports lighting and other sources of bright blue-rich light at night. But for those who take this kind of Russian Roulette risk and lose, the consequences are horrible. You can access a report with full details at the light pollution page of www.asv.org.au/.