A DARKERVEW Sounds Off on the Big Island Lights Question Posed

I wrote to Andrew Cooper earlier today about the Street Lights on the Big Island, and he responded with some interesting feedback that I hadn’t heard of before.

It’s a fairly long letter, and it still hasn’t gotten me convinced that the lighting on Big Island roads needs to be improved:

The streetlights do have an impact on the telescopes.  There is a reason
my website is called “A Darker View”, the impacts of light on
astronomical observation is significant.  Astronomers come to Hawai’i to
escape the massive lighting found around major metro areas, there are
few places in the mainland US unaffected by artificial light.  The
enormous amount of electric outdoor lighting has an impact on our lives,
our pocket books, on our health and on wildlife.  Many of these impacts
are quite negative.  We are in love with electric light and we use it
extravagantly.  I am not saying turn all the lights off, we need to
consider safety, but better design and better lights can reduce the need
for light and increase safety.  Use it where we need it and not


Astronomers prefer that the streetlights that are installed be low
pressure sodium (LPS), these are the yellow lights installed for all
civic lighting in Hawai’i.  These have two big advantages, they emit on
a single wavelength allowing astronomers to filter that wavelength out
of the data.  They are also far more power efficient to run, emitting
more light per watt than competing halide or mercury lights.  This saves
the County of Hawai’i and the taxpayers, who must pay the power bill for
all of these lights, an enormous amount of money.


A couple other advantages to LPS, the bulbs last longer and keep a good
light output until failure (competing technologies dim with age) and the
yellow light output (589nm) is nearer the peak photopic sensitivity of
the human eye, meaning we see better with less light and energy.  The
situation with respect to lighting type and effectiveness in safety is
complex and depends on a lot of factors.


It may be more a case of badly designed and poorly chosen lights.  Many
of the lights I do see on the island are older, inefficient designs.  A
modern light is much better at putting its light where needed, on the
ground and on the road and not all across the neighborhood around it.
The differences are primarily in the reflector and lens design, the
newer lights were designed on computer optical CAD software that takes
the guesswork out of the equation.  These lights give better
illumination on the road for the same amount of power and light.


Better lights for reducing glare and reducing light pollution are full
cutoff types.  I see a lot of the non-cutoff types where glare is a
problem, look for a big glass dome hanging below the light fixture, full
cutoff does not have this.  Without the full cutoff you see the light,
which is bright, but everything else, including the road below is dim in
comparison, this is a glare problem.  Full cutoff also has the advantage
of not shining in the windows of surrounding homes.


I have felt that many streets on the island, particularly in residential
neighborhoods are badly over-lit.  There is quite a bit of research that
shows that too much light at night messes with our hormonal cycles
needed for good sleep, particularly with melatonin, with a range of
health impacts.  Getting county lights out of the neighborhoods and onto
the streets and critical intersections would help without increasing the
power bills.  But considering the many people who do not understand the
issues, and are in love with light for all the wrong reasons, this is


Sorry about the long message, a bit of a pet peeve subject.  But much of
the astronomy community, amateur and professional is a little sensitive
on this subject.

Andrew Cooper

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