[AZ-Observing] Re: Daily Star Story About Tucson Sky Brightness Change in Past 20 Years
- From: "William R Wood" <w.wood@xxxxxxx>
- To: <az-observing@xxxxxxxxxxxxx>
- Date: Fri, 17 Sep 2010 09:23:47 -0700
Not easy for me to be optimistic based on the idea that things could be much
worse. I'm with Stan on this one and would be much happier if the pollution
graph line was curving down, instead of running flat in a few places and
rising in many.
As to my comment about shielding not being all that effective.....
Obviously things would be worse with no/less shielding but shielding is not
the answer since there is still tons of light reflected up after it hits the
ground (and even the best shielding allows way too much sideways light).
And I think shielding is being used as a solution to the problem, when it
isn't a solution at all. To me the core problem is that most folks think
more light is automatically better. But we used to get by with little or no
lights. And we certainly could get by with fewer and dimmer lights (better,
smarter engineering).
I view optimism on this issue (nothing personal of course) as acceptance or
endorsement of the status quo, which is negative to the cause of eliminating
or at least significantly reducing light pollution and light tresspass. If
astronomers (amateurs and pros) don't complain about light pollution, who
will?
Regards
Bill Wood
----- Original Message -----
From: "Tom Polakis" <tpolakis@xxxxxxx>
To: <az-observing@xxxxxxxxxxxxx>
Sent: Thursday, September 16, 2010 6:05 PM
Subject: [AZ-Observing] Re: Daily Star Story About Tucson Sky Brightness
Change in Past 20 Years
It's a sorry state of affairs when I'm the optimist. Let's review what's
been written.
Lake Michigan is disappearing under light dome by 2025. That's quite an
extrapolation, especially when Detroit -- more than 150 miles away -- is
being considered. I have visited the east shore of Lake Michigan at least
yearly for each of the 25 years I have been living in Arizona. The
Milwaukee and Chicago light domes have grown perceptibly during that time,
but still require some attention to spot. They have nearly zero impact on
the sky overhead.
Shielding has little effect on overhead sky brightness. It's in the numbers
mentioned in the Daily Star article, and by the Lowell astronomers who
conducted the study. Of course it has a profound effect. It's even
well-characterized in light pollution models. Those of us who were treated
to Chris Luginbuhl's SAC talk earlier this year could take away that
message. Imagine what our sky would look like today if cities operated
under unshielded Mercury vapor lamps.
The Antennas site is going to be mediocre in ten years time. I have watched
the size of the light dome grow from Sentinel over a 25-year period. It has
not been negligible, but the extent has less than doubled during that
period. And that's during a period of unprecedented growth, which shows no
signs of recurring.
We may be the last generation to see a dark sky in the continental U.S.
Look at the area around the Grand Canyon, a mere four hour drive from
Phoenix, and tell me what development is going to blot out the night sky in
the next few decades. Yes, you can see Las Vegas, but again, you have to
look for it.
The story was about measured light pollution from a site that's not in the
city, but is affected by its presence. The good news is that it has barely
changed in 20 years. Have amateur astronomers become such an aged segment
of the population that they don't know how to handle good news?
Tom
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