Some of these
data are from the International
Dark Sky Association. This is an excellent organization and
is strongly supported by Tamke-Allan
Observatory at Roane State Community College.
fixture shown at the left, especially with a Mercury Vapor Lamp
should NEVER be used. It wastes light that should be kept on the
ground. It causes glare that makes it more difficult to see nearby
objects and can actually reduce security because of the glare
that it produces. It causes light pollution over a wide area. Shields
can be added (make your own or buy one like those shown below) to
direct the light downward and save light.
Electric Utility currently supplies 175 watt mercury vapor fixtures
for home security lighting and 400 watt fixtures for street lighting.
We are asking them to choose to install well-designed light-saving
fixtures (that direct light downward) and to choose Sodium vapor
lighting instead of Mercury vapor. Many homes would welcome a smaller
fixture -- for example, 70 watt.
dark sky-friendly fixtures that may be useful for homes in east
Tennessee, two fixtures stand out, the GE SKYGARD 201AS and the
American Electric Lighting because they are avaliable with 70W HPS
(high-pressure sodium) lamps. Even 70W HPS can be excessive
for residential use.
(also see shields below): Shields
& Mods and Motion