Join the International Dark-Sky Association for seven days of celebration, learning and action!
Created in 2003 by high-school student Jennifer Barlow, International Dark Sky Week has grown to become a worldwide event and a key component of Global Astronomy Month. Each year it is held in April around Astronomy Day. This year celebrations begin Saturday, April 15, and run through Friday, April 21 (click here for resources to use during the week).
In explaining why she started the week, Barlow said, “I want people to be able to see the wonder of the night sky without the effects of light pollution. The universe is our view into our past and our vision into the future. … I want to help preserve its wonder.”
International Dark Sky Week draws attention to the problems associated with light pollution and promotes simple solutions available to mitigate it.
Also read “5 Ways to Celebrate Dark Sky Week“!
Light Pollution Matters
The nighttime environment is a crucial natural resource for all life on Earth, but the glow of uncontrolled outdoor lighting has hidden the stars, radically changing the nighttime environment.
Before the advent of electric light in the 20th century, our ancestors experienced a night sky brimming with stars that inspired science, religion, philosophy, art and literature including some of Shakespeare’s most famous sonnets.
The common heritage of a natural night sky is rapidly becoming unknown to the newest generations. In fact, millions of children across the globe will never see the Milky Way from their own homes.
We are only just beginning to understand the negative repercussions of losing this natural resource. A growing body of research suggests that the loss of the natural nighttime environment is causing serious harm to human health and the environment.
For nocturnal animals in particular, the introduction of artificial light at night could very well be the most devastating change humans have made to their environment. Light pollution also has deleterious effects on other organisms such as migrating birds, sea turtle hatchlings, and insects.
Humans are not immune to the negative effects of light in their nighttime spaces. Excessive exposure to artificial light at night, particularly blue light, has been linked to increased risks for obesity, depression, sleep disorders, diabetes and breast cancer.
Good Lighting Doesn’t Compromise Safety & Security
There is no clear scientific evidence that increased outdoor lighting deters crime. It may make us feel safer but it does not make us safer. The truth is bad outdoor lighting can decrease safety by making victims and property easier to see.
Glare from overly bright, unshielded lighting creates shadows in which criminals can hide. It also shines directly into our eyes, constricting our pupils. This diminishes the ability of our eyes to adapt to low-light conditions and leads to poorer nighttime vision, dangerous to motorists and pedestrians alike.
Another serious side effect of light pollution is wasted energy. Wasted energy costs money, contributes to greenhouse gas emissions and climate change, and compromises energy security.
What YOU Can Do
The good news is that light pollution is reversible and its solutions are immediate, simple and cost-effective. Here are a few simple things you can do to confront the problem and take back the night:
• Check around home. Shield outdoor lighting, or at least angle it downward, to minimize “light trespass” beyond your property lines. Use light only when and where needed. Motion detectors and timers can help. Use only the amount of light required for the task at hand.
• Attend or throw a star party. Many astronomy clubs and International Dark Sky Places are celebrating the week by holding public events under the stars. See our Events Calendar to find an event in your area (we update our calendar regularly, so be sure to keep checking back). If you have a dark sky related event, please let us know, so we can post it!
• Download, Watch, and Share “Losing the Dark,” a public service announcement about light pollution. It can be downloaded for free and is available in 13 languages.
• Talk to neighbors and your community. Explain that poorly shielded fixtures waste energy, produce glare and reduce visibility. Need inspiration? Check out our Get Involved page and our public outreach resources.
• Become a Citizen Scientist with GLOBE at Night or the Dark Sky Rangers and document light pollution in your neighborhood and share the results. Doing so, contributes to a global database of light pollution measurements.
• Photograph the sky and enter the 2018 International Earth and Sky Photo Contest, which aims to educate the public about light pollution (contest dates to be announced in early March).