[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[DSLF] Digest Number 1443
There are 4 messages in this issue.
Topics in this digest:
1. Lights Block Stars, Pollute Skies - ABQ Journal letter
From: "David Penasa" <dpenasa@unm...>
2. Fwd: 4th European Dark-Sky Symposium in Paris
From: ctstarwchr@aol...
3. Re: Lights Block Stars, Pollute Skies - ABQ Journal letter
From: "ctstarwchr" <ctstarwchr@aol...>
4. Re: Re: Lights Block Stars, Pollute Skies - ABQ Journal letter
From: Yvan Dutil <yvan.dutil@sympatico...>
________________________________________________________________________
________________________________________________________________________
Message: 1
Date: Tue, 7 Sep 2004 08:50:28 -0600
From: "David Penasa" <dpenasa@unm...>
Subject: Lights Block Stars, Pollute Skies - ABQ Journal letter
Sunday, September 5, 2004
Lights Block Stars, Pollute Skies By Dr. Vikram Alladi
Alladi lives in Las Vegas, N.M., and is promoting a dark-sky protection
ordinance for that city.
http://abqjournal.com/north/opinion/218561northoped09-05-04.htm
________________________________________________________________________
________________________________________________________________________
Message: 2
Date: Tue, 7 Sep 2004 13:33:51 EDT
From: ctstarwchr@aol...
Subject: Fwd: 4th European Dark-Sky Symposium in Paris
Presented for the courtesy of our colleagues in Europe...
----------- Forwarded Message ------------
Date: Sat, 28 Aug 2004 23:24:48 -0000
From: "Emmanuel Brochard" <brochard@club-internet...>
Dear friends,
Please find below the nearly final list of communications, abstracts
and schedule for oral presentations at the 4th Dark-Sky European
Symposium. (Paris, September 24-25, 2004)
http://www.astrosurf.com/anpcn/association/ag/2004/index.en.php
It is still possible to subscribe.
Sincerely,
Association Nationale pour la Protection du Ciel Nocturne (A.N.P.C.N)
http://www.astrosurf.com/anpcn/ --anpcn@astrosurf...--
A.N.P.C.N c/o S.A.F, 3 rue Beethoven, 75016 Paris, France
_____________________________________________________________________
Le trésorier : Emmanuel Brochard --brochard@club-internet...--
11 rue Tournefort, 75005 Paris, France 01 45 87 88 98
[Non-text portions of this message have been removed]
________________________________________________________________________
________________________________________________________________________
Message: 3
Date: Tue, 07 Sep 2004 23:09:00 -0000
From: "ctstarwchr" <ctstarwchr@aol...>
Subject: Re: Lights Block Stars, Pollute Skies - ABQ Journal letter
Thanks David. Overall this was a very good article
and I wish this fellow the best of luck with his
efforts because he is perhaps in one of the world's
most challenging environments.
The example of the 1994 earthquake in Los Angeles was
excellent because people who had never seen the night
sky were frightened by their first sight of the Milky Way.
The public believed the cloud mysteriously cutting the sky
in half was a product of the recent earthquake. There was
an account of this published by the Lonely Planet several
years ago during a discussion about the newly established
Torrance Barrens Dark Sky Preserve in Canada.
One thing mentioned in the article that concerns me is
when people striving for obtrusive lighting reform advocate
good fixtures by claiming that full shielding sends all of
the fixture's light downward rather than outward. That is
very misleading and cannot be any farther from the truth!
We need to think more carefully about the implications this
misinformation imposes on our quest because fully shielded
lighting and ALL of the IES cutoff classes send light outward
at angles up to 89 vertical degrees, which means OUTWARD.
This is technically in a downward direction if we examine
its geometry, however, downward to most reasonably intelligent
people usually means straight down below the fixture. This
gives the wrong impression that more lighting equipment will
be needed to provide even illumination required for safety
and reasonably good security demanded by current standards.
The best performing fixtures, regardless of their cutoff type,
send their beam of maximum candlepower outward at vertical
angles between 66 and 72 degrees. Any fixture exhibiting
that level of performance is technically classified as having
a medium vertical distribution. This is the sole component of
luminaire performance that allows the greatest pole spacing
distance needed to reduce energy waste while also optimizing
the lighting uniformity. It is predominantly the uniformity
of the light distribution opposed to the density of the light
(footcandles or lux levels) on ground surfaces that helps us
to see better in a darkened outdoor environment.
Since we have no complementary surfaces like walls or ceilings
with light colored surfaces to bounce available light off of
like we have with indoor environments, it is the vertical
angle of distribution for the beam of maximum candlepower
that governs the limits of performance in most outdoor lighting
designs. If a fixture is meant for lighting a roadway or a
path do not consider a short vertical distribution or suffer
the consequences with hot spots and poor uniformity along with
needing a forest of poles that raise the costs and the light
levels sometimes to astronomical proportions.
Anyone who does not understand that should take a walk outdoors
on a clear night during a full moon not in the presence of manmade
light to see just how far and with how much detail objects around
you will appear. Although the illuminance level will very likely
be around 0.01 footcandles (1/100) its uniformity is 1:1, which
allows the eye to adapt successfully to that low level of
brightness. Yes, there have been some disputes in the past
regarding that light level the IES has published for illuminance
cast by an average full moon, but after two years of measuring
it on clear nights I have never once seen a reading higher than
0.01 footcandles at 105 feet above sea level at 41 degrees
latitude.
I recently spotted the Advanced Lighting Guidelines published
that the full moon delivered ground illuminance between 0.1 and
1 footcandle (1 to 10 lux), which is a significant error imposing
several magnitudes of exaggeration. It appears on page 20 of the
PDF and I hope this will be corrected in the next iteration.
Clear skies and good seeing,
Keep looking up!
Cliff Haas
http://members.aol.com/ctcadman
http://www.crlaction.org
--- In DarkSky-list@yahoogroups..., "David Penasa" <dpenasa@u.....>
wrote:
> Alladi lives in Las Vegas, N.M., and is promoting a dark-sky
> protection ordinance for that city.
>
> http://abqjournal.com/north/opinion/218561northoped09-05-04.htm
________________________________________________________________________
________________________________________________________________________
Message: 4
Date: Tue, 07 Sep 2004 20:49:26 -0400
From: Yvan Dutil <yvan.dutil@sympatico...>
Subject: Re: Re: Lights Block Stars, Pollute Skies - ABQ Journal letter
>
I had teh same problem recently in a discussion with an architect. She
was swering than the full moon was a few tens of lux, and a streelight a
few hundred. To its defense I must say she was first an lighting
interior architecte. This explain the bias. However, she change her mind
when I send her dozens of reference claiming that the Full moon is
between 0.1 and 0.2 Lux
Yvan Dutil
> I recently spotted the Advanced Lighting Guidelines published
> that the full moon delivered ground illuminance between 0.1 and
> 1 footcandle (1 to 10 lux), which is a significant error imposing
> several magnitudes of exaggeration. It appears on page 20 of the
> PDF and I hope this will be corrected in the next iteration.
>
> Clear skies and good seeing,
> Keep looking up!
>
> Cliff Haas
> http://members.aol.com/ctcadman
> http://www.crlaction.org
>
> --
________________________________________________________________________
________________________________________________________________________
_________________________________________________
To subscribe to the DarkSky List Forum send email to:
DarkSky-list-subscribe@yahoogroups... or visit:
http://groups.yahoo.com/group/DarkSky-list/join
Help save your town from obtrusive lighting --
Invite your Planning and Zoning department and
local officials to join us! Please visit the IDA & CRL
websites at http://www.darksky.org and
http://www.crlaction.org frequently, too!
------------------------------------------------------------------------
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/DarkSky-list/
<*> To unsubscribe from this group, send an email to:
DarkSky-list-unsubscribe@yahoogroups...
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
------------------------------------------------------------------------