International Dark Sky Week & Lighting Inventories
NIGHT SKY OVER MOSIER
Written by Michael KcKeag, DarkSky Oregon Board Member
Milky Way arching over the Gorge. Lights of Mosier far right.
International Dark Sky Week is a world wide celebration of dark night skies, held every April during new moon week, this year 13-20 April. You will find suggestions for many ways you can participate on the International Dark Sky Week website. That week I will be providing visitors telescope views of the night sky at the PLAYA Outback Dark Sky Celebration at Summer Lake.
Addressing light pollution can start at home. Consider celebrating International Dark Sky Week by assessing your own outdoor lighting. Detailed instructions for conducting a home outdoor lighting assessment can be found on the DarkSky International website.
In evaluating your outdoor lighting you will be guided by five questions:
Is the light useful?
Is it targeted, illuminating only what is necessary to serve its intended purpose?
Is it low level, only bright enough to serve its intended purpose, and no brighter?
Is it suitably controlled, only on when needed, otherwise switched off, manually, or by timer or motion sensor?
Is it warm colored? Warm colored, longer wavelength light, scatters less through the atmosphere, produces less glare, and has less impact on human health and wildlife habitat.
The Home Outdoor Lighting Assessment provides background on the varieties of light pollution, the impacts of light pollution on human health and wildlife, an assessment checklist, and guidance on replacement blubs and fixtures. DarkSky International has a DarkSky Approved fixture certification program, with an extensive online catalog of certified fixtures.
At our home our outdoor lights are wall sconces that qualify as "fully shielded" (no light cast above horizontal), but our original bulbs were not warm-colored. A few years ago I visited Home Depot in The Dalles looking for warm-colored, LED bulbs. I only found one product that met my needs among the countless bulbs on display.
The other day I visited Home Depot and now found a significant selection of suitably warm-colored LED bulbs, in many styles. Avoid bulbs described as "white", "bright white", or "daylight." Look for bulbs described as "soft white", "yellow", etc. They will have a color temperature rating under 3000K, often 2700K. Brightness is described in lumens. Select bulbs with a brightness rating no higher than necessary for the application. 450 lumens will be sufficient for many situations. 1500 lumens may be deemed necessary in others.
I bought samples of four bulbs for testing: 1) Feit 40w 450lumens 2700K, 2) Feit 100w 1500lumens 2700K, 3) Ecosmart 60w yellow "bug light", 4) Ecosmart 60w soft white 2700K.
That night I set up a camera to photograph one of our exterior wall sconce fixtures, with the original, and each of the sample bulbs installed. I also measured color temperature, and illuminance at ground level directly below the fixture, with a spectrometer.
Here is a summary of the results:
Bulb evaluation results: photograph, spectrometer data, bulb package, measured illuminance at ground level in lux, and color temperature in degrees kelvin.
You will find very few DarkSky certified light fixtures at Home Depot. I found only three among the wall of fixtures on display. They are obvious by their design, which prevents light from being cast above horizontal, making them qualify as "fully shielded". They carry the IDA logo on their label (DarkSky International was originally branded as the International DarkSky Association).
The only three DarkSky certified fixtures I found on display at Home Depot, upper left, center, and lower right. Their labels carry the original "IDA certified" logo. They were the only fixtures I saw on display that would quality as fully shielded.
While you are out accessing your outdoor lighting, look up. Mosier still has relatively dark night skies. We can still see stars overhead on a clear night, and even a hint of the Milky Way. Many communities cannot make that claim. The night sky over Mosier can be even darker.