The Great Light Switch Out

Humans are diurnal creatures; we like the light. Because of this desire for light, we spend millions every year to illuminate our front porches, back yards, and night sky. One of the easiest ways to reduce unwanted glare and light trespass is to use fully shielded fixtures. When you use a fully shielded fixture you not only reduce these side effects of light pollution, but you can also reduce the wattage of the lamp in the fixture. The Great Light Switch Out program encourages homeowners to remove and replace their residential light fixtures to ones that are energy efficient and dark sky friendly.

By providing a Homeowner’s Guide to Outdoor Lighting, fixture recommendations, and suggestions for retail outlets to purchase these fixtures, the Great Light Switch Out will promote the importance of quality outdoor lighting for your home, your neighborhood, and your environment.

Pineapple Juice Can Shield
Description: This simple demonstration of placing a can over a bare bulb (photo on right) shows the importance that shielding has. Not only is the ground more illuminated, but glare is reduced, and the wattage was reduced by 33%. Credit: Southern Arizona IDA Section

As part of the Homeowner’s Guide to Outdoor Lighting, the International Dark-Sky Association has prepared a document that can be found at For further information, visit, select “Quality Lighting” and then select “Homeowners Guide”.

Check out the 365 Days of Astronomy Podcast on October 24, 2009 to help to prepare you for daylight savings time, when more people begin using their outdoor lights for longer periods of time.