How to make your house dark-sky friendly

Dark skies are good for stargazing, for wildlife and for human health alike. The Royal Astronomical Society of Canada supports numerous community initiatives to reduce sky glow and to promote darker skies for astronomy, but also, we cannot forget the actions that we can take at home.

Below are a few starter tips for making your house (or apartment, which would apply to some of these tips) a dark sky friendly dwelling.

The lights from even a few buildings can have an effect on how dark the sky is nearby, as seen in a rural area outside of Athabasca, Alberta. (Allendria Brunjes)

Fix your window shades

While turning off all lights would be the easiest answer to stop light pollution leaking to the outside, it’s not always practical. So when it’s dark outside, turn on every light in your house and then step far enough away so you can see how much light your house emits.

If you see light coming through the window shades, it’s time for a change. Wooden shutters that can pull shut inside your house are ideal; otherwise, you can invest in blackout curtains. (Incidentally, blackout curtains may also help you sleep better at night, since no outside light will be coming into your bedroom.)

Fix your outdoor lighting direction

Again, the ideal is to turn off outdoor lighting completely, but that may not work in all situations.

The first step is to attempt not to have persistent outdoor lighting, which means wiring a motion sensor into your lamp so that the bulb only turns on when it is necessary to do so. The second step is, for any light that might be emitted, to block any rays that are pointing up uselessly into the sky. How to set that up will depend on your lighting situation, but find a way to put a light blocker or shade on the top so that all available light is directed towards the ground.

Fix your outdoor lighting type

Another practical thing to do is to invest in lighting that has been approved by The RASC or the International Dark-Sky Association, to make sure you are using equipment that will protect the sky.

The IDA’s product list is meant to “minimize glare while reducing light trespass and skyglow”, and also to reduce the amount of blue light that is being emitted into the environment (which can disrupt insect or animal day-night cycles.) The RASC links to several types of lighting that could be helpful, including Full Cut-Off Fixtures, and a Glare Buster that can help illuminate pedestrian walkways without creating undue sky glow.

Elizabeth Howell (Ph.D.) is a Canadian space journalist who has been obsessed with the topic ever since she, as a young teenager, saw the movie Apollo 13 in 1996. She grew up wanting to be an astronaut. While that hasn’t happened (yet), Elizabeth has seen five human spaceflight launches — including two from Kazakhstan — and she participated in a simulated Red Planet mission at the Mars Society’s Mars Desert Research Station in Utah.