People who travel to remote places often do so for the chance to enjoy stargazing under dark skies. This experience requires the absence of artificial light shining into the sky or lighting up the horizon. This light pollution, as anyone who travels much knows, has invaded most of the US landscape, and must now be a factor when choosing a potential stargazing destination.
Measuring the Dark
Light invasion, or lack of it, can be measured with a photodiode light sensor such as The Sky Quality Meter, which accumulates photons (particles of light) and calculates a reading of from 17 to 23 magnitudes per acrsecond. That’s astronomer talk, but basically higher numbers mean more darkness. A sky measuring 17 is about 100 times brighter than one measuring 22. Anthony Tekatch of Unihedron, maker of the Sky Quality Meter, says readings higher than 22 are unlikely. His personal darkest is 21.80. The website allow users to post their measurements.
Some places in Texas remain significantly dark at night. For example, in November of 2006, skies above Guadalupe Mountains Pine Springs campground measured 21.95 on the Sky Quality Meter. Readings at Devils River State Natural Area in January of 2007 averaged 21.83, and at Big Bend’s Pine Canyon 4WD camp site, shortly after sunset and before the full moon burst over the mountains, 21.82. Also in January of 2007, around mile 20 in Padre Island National Seashore, readings were 21.56.
Many locations, while remote, are affected by sky glow from nearby towns and cities and isolated sources of light like towers. The International Dark Sky Association estimates that roughly half of our lighting is inefficient, shines up into the sky, or supplies more light than needed. Eliminating that half would help preserve dark skies, and views of the stars.
Darker Skies at Home
Neighborhoods can be made more dark-sky friendly if residents approach the municipality about shielding street lights or converting them to LED, which will reduce both energy and maintenance costs. Ann Arbor, Michigan, converted downtown street lights to LED. Individuals can be advocates for dark skies by pointing out lighting that shines into the sky, people’s faces, or anywhere else it isn’t needed, both at public facilities and local businesses. The International Dark-Sky Association provides information regarding lighting that is effective and safe and yet reduces light pollution.
Porch light fixtures that shine in all directions actually create glare and make it harder for people to see where they are walking. These can be replaced with IDA-approved, shielded fixtures that direct light downward, where it is needed. Residents, too, can use LED for outdoor lighting. The initial cost is greater, but can be recouped that through reduced electricity costs (some LEDs use as much as 85 percent less) and longer life. Cree LED Lighting Solutions predicts its LR6 light will last more than 20 years under normal use (50,000 hours). LED bulbs also have instant on-off capability, allowing for greater use of motion detector sensors and dimmers, helping further reduce light pollution. Other benefits to consider: LED lights produce a more natural look with fewer shadows, greater detail and true colors, and they do not contain lead or mercury.
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