Starting tonight and running through the week, there is a little-recognized, international event going on: International Dark Sky Week, which serves to raise awareness about astronomers' desires to preserve the night sky, the hazards of light pollution, and the vast amount of money wasted on wasted energy.
So, what about Dark Sky Week?
Any astronomer knows that there is nothing like artificial lighting, commonly termed “light pollution,” to ruin a good night's observing. As an extension, after one views at a true dark sky site, it may be hard to ever want to observe from home again as the situation will seem utterly depressing. For people who are not used to looking up at the night sky, there are still ways to notice all the light. Have you ever looked up in the sky to see reddish-pink clouds or gone out on a night with freshly fallen snow and found it nearly as bright as day? Well, that's further, non-astronomical proof of light pollution.
So why should non-astronomers care? There are many reasons.
First: money. Believe it or not, about 50% of all outdoor lighting is wasted. How is this done? Simple, lighting left unshielded emits light in all directions, not just to the ground where it is intended to go. So, for every dollar paid on an electric bill for lighting costs, 50 cents of that is spent on light that serves no purpose other than to light the night sky.
Second: wildlife. Unlike humans, animals don't have clocks with which to tell time. With the increase in artificial light, some species are getting their days and nights mixed up, which can throw off sleep patterns and thus, through the creation of tired animals, increase chances of predation. Also, it is thought that some birds use the Moon and stars for navigation. Obviously, without the starry signposts, the birds may be getting lost. Perhaps the best known problem of light pollution is with sea turtle babies. Which are increasingly finding their way away from the ocean to to lighting on coastal cities.
Third (and something everyone should care about): human health. Believe it or not research is starting to show that not even we human are immune from the effect of artificial lighting. With all the extra light, the production of melatonin, the hormone that regulates sleep, is impacted, thus leading to sleep disorders, which can then branch out to create other health problems. Some new research even suggests that the artificial lighting/the interruption of natural sleep patterns can create an increased risk for some cancers. However, it should be known that this research has just begun and the exact reason for the correlations is unknown.
In short, there are many reasons for caring about light pollution, even for non-astronomers. Between money, health, and the environment, light pollution does much more harm than just washing-out the beautiful night sky.