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Dr
Nick White investigates.
Light
pollution results when an exterior light, such as a streetlight
or a security light, directs light upwards into the night sky. This
upward-bound light gets scattered in the atmosphere causing an orange
foggy glow to appear above a town.
For
an astronomer trying to peer out into space, this glow presents
itself as an almost impenetrable barrier that renders all but the
brightest stars invisible. Light pollution is a consequence of poor
or lazy engineering that is both unnecessary and, to a large extent,
avoidable.
A
waste of money and energy
Reducing light pollution does not mean reducing the level of lighting
required for usual outdoor night-time activities. Normal lighting
levels can be achieved with well designed astronomer-friendly lights
whose optics direct the light where it is needed - on the ground.
Lighting up and washing out the night sky serves no useful purpose
and in my opinion defines "poor" external lighting.
But
more is at stake than only saving the night-sky environment. Wasting
energy and money lighting up the night sky is surely to be avoided
if possible. Also, there are a growing number of issues concerning
light trespass, disability glare and the general eyesores that somehow
pass for "good" exterior lighting.
Light
trespass involves light shining onto a neighbouring property
where illumination is not wanted.
Disability glare occurs when light shining into the eyes of
a person causes that person to be inhibited from performing safely
a given task in the vicinity of the light source. For example, architectural
lights and security lights sometimes shine into the eyes of passing
motorists, causing a hazard to both motorists and pedestrians.
Whether
or not a light source is deemed an eyesore is generally much
more subjective although there are a few clear-cut cases. For example,
obtrusive lighting in the National Park goes against the spirit
of national parks and indeed there are fairly strict guidelines
that aim to limit light pollution in rural areas.
As
far as towns are concerned, there should be more debate about the
aesthetic feel that people want their towns to give them at night.
Personally, I feel that streets are over-lit at night and this usually
spoils the character of a town.
See
the light - or see the sky
In general, there are plenty examples of light pollution, light
trespass and disability glare to be found all over Cumbria.
The
problem is continuing to increase and so local amateur astronomers
are involved in the nationwide campaigns for dark skies.
They
also hope to encourage people to help bring about a reduction in
the levels of light pollution.
However,
if current outdoor lighting trends continue, particularly the indiscriminate
use of security and architectural lighting, it is likely that the
local night-sky environment will decay further and people of Cumbria
will join the majority of UK citizens who are no longer in a position
to enjoy the starry starry night.
Feature
by Dr Nick White
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