The Night Sky and Light Pollution - What Happened to the Milky Way?
Have You Seen the Milky Way?
Do you remember going outdoors on a clear winter night and seeing the brilliant star-studded sky? Or lying on a blanket in the summer with your best friend and identifying the constellations? You could see the Milky Way leaving a creamy streak across the sky with twinkling stars everywhere. Have you looked up at the sky lately? Chances are, unless you live in a very unpopulated area, you won't see the Milky Way because light pollution in the U.S. has made it invisible in about two thirds of the country.
Do you remember the star-studded sky?
Growing up in the country in rural New Jersey, I remember coming home from the movies late at night and seeing the incredible night sky. When we came to our house, there was no porch light on, and chances were that you didn't really need a light because the moon and the stars provided enough light to find our way to the door. Although our neighbors weren't close, none of them had halogen lights in their yards or security spotlights lighting up every corner of their house and shining like beacons into the air. Now and then someone left a porch light on, but it was low light, just enough to light the steps and the front door.
Today, it's common for every house to have bright lights lighting up their driveways, porches and lawns all night long. Even without street lights, it would be easy to see your way through the average housing development by the light of the burning lights on each house.
When you drive out to the country where there are no houses, you'll likely see the glow from nearby towns, cities, football fields, malls and car dealerships lighting up the night sky. You may see a few of the brightest stars, but it's unlikely that you'll actually see the Milky Way.
It's sad to think of our children growing up and never actually seeing the beautiful night sky that we enjoyed from our back yards. Unless they are lucky enough to go camping in a National Park or in some remote region, the light pollution will obscure much of the beauty of the night sky.
Snow Geese Migrating
Light Pollution Disrupts Nature
Light pollution is not only annoying for those who love to enjoy the beauty of the night sky. Biologists and ecological groups say that the glow emanating from cities and suburbs disrupts the biological rhythms of wildlife and can interfere with the behavior of nocturnal animals.
Video of Baby Sea Turtles Hatching
Light Pollution as Seen From Space
Light pollution that occurs at unnatural times and places can have a dire effect on animals. In an article for the journal Frontiers in Ecology and the Environment, a collaboration of scientists, biologists and ecologists showed that false cues from polarized, or reflected light, can trigger animals to make mistakes that can cause injury and even death.
Light Pollution Harms Sea Turtles, Migrating Birds and Other Wildlife
In one example, baby sea turtles use reflected light from the ocean as a beacon to head to the sea. When there are bright street lights on the shore, the turtles can migrate the wrong way and die. Many birds, insects and animals can mistake urban lights reflecting off dark shiny horizontal surfaces for natural moon or starlight reflecting off water. This can cause them to make deadly mistakes in laying eggs, nesting or migration.
The U.S. Fish and Wildlife Service estimates that four to five million migrating birds die each year because the are disoriented by bright lights on tall buildings.
The term scotobiology describes the study of biology as directly and specifically affected by darkness. Scientists have found that many organisms require periods of darkness in order to function naturally. Even short periods of bright light interrupting the required dark period can prevent some plants and animals from behaving in the required manner. Light pollution can interfere with breeding, control flowering in plants and affect winter dormancy. In humans, it can effect the immune system.
Telescope for Viewing Night Sky
The Cost of Light Pollution
Cost of light pollution in the U.S.: $10 Billion annualy.
Cost to individual households of outdoor lights left on from dusk to dawn:
- One 150 watt incandescent bulbwill cost $66.99 if run from dusk to dawn.
- One quartz halogen 500 watt bulb will cost $209.54/year.
- One quartz halogen 1000 watt bulb will cost $$419/year.
- One Mercury Vapor light will cost $419 a year.
- One 100 watt incandescent bulb will cost 62.86 a year.
- One Compact Flurescent (CFL) will cost $17.60 a year.
*Note: Calculations were based on a national average of 10.5¢ per kilowatt hour.
Light Pollution Affects Humans
Recent studies in humans has found that light at night interferes with natural circadian rhythms. Light at night has even been found to interfere with natural circadian rhythms and the human body's internal clock claims an article published by the Journal of Neuroscience. In an article by Davis S, Mirick DK, Stevens RG. in the Journal of the National Cancer Institute entitled Night Shift Work, Light at Night, and Risk of Breast Cancer, researchers found that light at night suppressed the production of melatonin and increased the risk of breast cancer.
It has been shown that the absence of darkness at night contributes to insomnia and restless sleep. This can also cause increased stress levels and health problems that are associated with stress.
What You Can Do to Reduce Light Pollution
- Turn off lights when they’re not needed.
- Use outdoor lights only when they’re needed.
- Use lower wattage bulbs.
- Use solar powered walkway lights to light walkways and stairs.
- Outdoor light fixtures should direct light downward, at less than a 90° angle. Install only full cut-ff fixtures that direct light to the ground where it’s needed rather that upwards.
- Reduce light trespass by ensuring that your lights do not light up your neighbor's yard or shine on his house.
- Install motion detectors on security lights rather than have them on all the time.
Light Pollution Stealing Night Sky
Does your city or town have light pollution ordinances?
What Happened To The Milky Way?
We can blame light pollution on city lights and lights of shopping malls and car dealerships, but it isn't just that. Every light that we shine into the sky contributes to the light pollution of our planet.
Light Pollution is My Pet Peeve!
As an RVer and camper, light pollution is one of my biggest pet peeves. Just when you think you are leading a life that brings you closer to nature, you park next to someone who leaves spotlights on all night or pull into a campground with street lights as bright as day.
At our home base in a quiet little cul-de-sac off the beaten path, a few neighbors have installed halogen lights on every corner of their house that light up the whole street. Unshaded porch lights are commonly left on all night, and it's impossible to sit outside on our porch at night without being blinded by glare from someone's lights. It's little wonder that the environment is harmed by these lights - I know I hate them!
Proper Use of Lights Can Reduce Light Pollution
Of course, no one expects everyone to shut off all their lights, but there are simple things you can do to reduce light pollution. Use hooded light fixtures that point light down where it's needed rather that into the air or at the neighbor's house. Use lower wattage bulbs. Turn off lights when they're not needed. Be aware of what your lights are doing. See shaded box at right for more tips.
Because of light pollution two thirds of the U.S. population can't see the Milky Way. One porch light isn't going to mean that much, but millions of lights, porch lights and security lights, street lights, flood lights, parking lot lights, business sign lights - they all add up to light pollution that affects our environment and ruins our enjoyment of the night sky.
Is it worth it to you?
The Milky Way as Seen From Death Valley National Park
Light Pollution Poll
What Measures Do You Take To Reduce Light Pollution?
Important Light Pollution Links and Lighting Cost Calculator
The mission of the International Dark-Sky Association (IDA) is to preserve and protect the nighttime environment and our heritage of dark skies through environmentally responsible outdoor lighting.
- Lighting Cost Calculator
Find out what that light costs you to operate and find out if you could save by switching to another type of lighting.
- Night Shift Work, Light at Night, and Risk of Breast Cancer
By Scott Davis, Dana K. Mirick and Richard G. Stevens. Exposure to light at night may increase the risk of breast cancer by suppressing the normal nocturnal production of melatonin by the pineal gland, which, in turn, could increase the
- Light pollution - Wikipedia, the free encyclopedia
This article explores various aspects of light pollution world-wide.
- Light Pollution: Causes and Cures
Light pollution has caused a severe decrease in the visibility of the night sky. Check how much and find out what you can do about it.
© 2011 Stephanie Henkel