Image Credit: Todd Carlson / Environmental Health Perspectives
Humans are primarily diurnal creatures. This means we like light. We wake up when the sun is up, we get tired and sleep when the sun has set. We feel groggy on gray days. We are afraid of the dark, often even when we know there is nothing to be worried about. We don't see as well in the dark as during the day.
Our preference for light is encoded in our genes. It's the result of millions of years of evolution. Our ancestors hunted and gathered by day. At night, they stayed huddled together, lest they be eaten by lions and tigers and bears (oh my!). So it is natural that, now that we have the power to make artificial light, we want to flood the places where we live with light. We feel safer. We can move about more freely and with less danger.
But now we are discovering that our proclivity to shine light into every dark corner is not necessarily a good thing. I don't have the space to illuminate (ha!) each of the following topics, but clicking on the links will give you further information:
- Much of our lighting (especially outdoor lighting) is wasteful.
- It uses a lot of energy.
- Half of the light goes out into space instead of down on the ground where we need it.
- Often the design is such that the lighting doesn't really help us see better.
- Excess lighting is bad for the environment
- Excess lighting is even bad for our health(!).
- Excess lighting prohibits us from seeing the wonders of the night sky
This is why excess lighting is often referred to as light pollution. It's wasteful, harmful, and it looks bad. Just look at the picture above, taken in Toronto during and after an electrical blackout.
The great thing is that we know how to fix all of these problems, and the cost isn't, umm, astronomical. Yes, we could just turn off all lights, but I realize that is a silly suggestion that will never happen. However, more reasonable solutions exist, including using more carefully-designed light fixtures, energy-efficient light bulbs, and turning lights off where they aren't needed. Most, if not all, costs of solving light pollution are recouped quickly through energy savings. The environmental benefits and renewed views of the sky from the cleaning up of light pollution are added bonuses.
As part of the International Year of Astronomy, we are sponsoring a Dark Skies Awareness campaign. We're not trying to get people to stop using lights; we're trying to get people to use lights more intelligently. It saves money, saves energy, helps the ecosystem, makes us healthier, and it re-opens the city skies to stargazing. Learn more here or from the International Dark Sky Association!