If you’ve ever read Isaac Asimov’s Nightfall or remember the Star Trek: Enterprise episode “Catwalk,” you might have an idea what it is like not to have a starry sky every night.
In Nightfall, the planet Lagash is in a system containing six stars; therefore, there is never night. Only once every two thousand years the alignment is such that only one sun is up, and an eclipse occurs due to another orbiting body which produces a brief night and a glimpse of the stars. In “Catwalk,” the planet in question is in a binary system such that it has only four days of night in any given month.
We here on Earth do not have such problems, or do we?
On one of my astronomical observing trips to Chile, I was able to see my own shadow on a moonless night from just the light of the stars from the Milky Way. I had never seen so many stars.
If you live in any of the urban or suburban areas of our planet, you probably have never seen the full splendor of the night sky, either. Why is that?
Go outside at night and look around. What do you see? I bet that most of the illumination you see will be from artificial light sources such as street lights, large advertising signs, and building lights from residences and businesses.
A century ago even in the cities people could look up and see the stars because there was much less artificial light. Do we really need all this light? You might argue that it would not be safe to walk the streets without proper illumination. You want a light in front of the door to your house and in front of the garage.
All of that is well and good, but as it turns out, most of the light given off by these “safety” lights is actually wasted. Look at the image below. The street light illuminates an area on the street, which is where you need the light. But it also lights the house whose inhabitants do not want it, it produces glare which can be distracting to drivers, it negatively influences nocturnal wild life, and it reflects light upwards and drowns out the light of the stars. The light goes where we don’t want it, making us spend more money on energy, and depriving us of a starry night sky.
Figure 1: description. Source: Anezka Gocova, in “The Night Issue,” Alternatives Journal 39:5 (2013).
Figure 2: The photo on the left shows the usual view of the house. The photo on the right shows the house during the 2003 Northeast blackout. Photo by Todd Carlson.
So, what can we do? Turn off the lights? As an example Figure 2 shows us what one place looked like during a major power outage.
Some countries have instituted measures to turn down outside lighting after certain hours. Growing up in Berlin, Germany, I remember well when the street lights went to half-light (two bulbs instead of all four) at 11pm. Other places, such as towns and cities near major astronomical observatories like Tucson, Arizona, and Hilo, Hawai`i, have switched to low-color-temperature LED lights that are much less bright. These are measures that have to be taken by local and regional governments. You can help by petitioning for such ways of lighting.
But what else can individual citizens do? Actually, you can do quite a lot regarding the lighting that you control.
1. Use light only where and when you need it. For example, use timed lights and motion-sensor lights on the outside of your house and in your driveway.
2. Shield your outdoor lights so that they illuminate only the ground they are supposed to light. That keeps you from bothering your neighbors, and it also prevents light reflection upwards.
3. Use low-color-temperature LED lights. They are bright enough for the purpose and produce much less glare.
4. Draw your blinds at night. It not only gives you privacy, but it also prevents light from leaking out and contributing to the excess outdoor light.
5. Get involved in the light pollution issue and petition your local government to install sensible shielded outdoor lights.
Let’s all take steps to help preserve our dark starry skies for future generations.
Here are a few links for you if you’d like to know more about this topic. The International Dark Sky Association can help you with information and contacts.
The International Dark Sky Association:
Information on outdoor lighting: