Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

General Astronomy >> Light Pollution

Pages: 1
desertstars

*****

Reged: 11/05/03

Loc: Tucson, AZ
Historical Context
      #5910246 - 06/08/13 06:50 PM

This may be impossible, but before giving up I thought I'd give this group a crack at it.

I started star gazing in a serious way just as I became a teenager, in a small Illinois town named New Lenox. My home town was all of six miles east of Joliet, and roughly 30 miles southwest of the Chicago metro area as it existed in the early 70s. This early astronomy episode lasted from the summer of 1969 thought the autumn of 1975.

I clearly recall the summer Milky Way showing plenty of detail. The Andromeda Galaxy was easily visible, naked eye (once I learned where to look!) I can't remember ever looking for, or finding, M33 - so that benchmark is unavailable. I can remember the glow of Joliet and Chicago near their respective horizons, especially in cloudy weather. Clouds overhead are, in memory, not quite black, but did not have the brightness of clouds I see over me at night, here in Tucson.

I'm trying to get a handle on the conditions under which I started, for the sake of a book I plan to write. Memory alone allows for a rough estimate, but I'd like to do better if possible. So, I have two questions:

Are there historical records of what we now call light pollution from that time?

Failing that, what would you assess the conditions of a clear night described above to be? Use whatever scale of measurement suits you.

Thoughts and suggestions would be greatly appreciated. TIA


Post Extras: Print Post   Remind Me!   Notify Moderator  
BrooksObs
professor emeritus


Reged: 12/08/12

Re: Historical Context new [Re: desertstars]
      #5911990 - 06/09/13 08:34 PM

To my knowledge, no country-spanning assessment of light pollution around individual cities accurately documenting conditions from the early 1970's exists.

While your description of the skies you recall is not overly detailed, what you do provide seems to correspond most closely to class 3, or perhaps class 4, conditions on the Bortle Dark Sky Scale (see S&T website under the Resources topic and headed up Saving Dark Skies).

BrooksObs

Edited by BrooksObs (06/09/13 08:39 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
desertstars

*****

Reged: 11/05/03

Loc: Tucson, AZ
Re: Historical Context new [Re: BrooksObs]
      #5912226 - 06/09/13 10:52 PM

That's what I was afraid of. My own searches have turned up nothing of the sort.

I'm going back and forth between class 3 and class 4, as well, which is why I've played this long shot. Closer to 3 than 4, I think, but... So many of the items used on the Bortle Scale to assess condition are things that I can't remember trying to see, naked eye. And am I remembering clouds lit by moonlight? Or the city of Joliet?

I do remember having trouble finding my way to the telescope without a flashlight, which is why I'm currently leaning toward class 3.

Thanks for the response!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Tony Flanders
Postmaster
*****

Reged: 05/18/06

Loc: Cambridge, MA, USA
Re: Historical Context new [Re: desertstars]
      #5912462 - 06/10/13 06:10 AM

Quote:

I clearly recall the summer Milky Way showing plenty of detail. The Andromeda Galaxy was easily visible, naked eye (once I learned where to look!)




Unfortunately, that's not enough information to rate the skies with any degree of accuracy. I would say that the Andromeda Galaxy is easily visible naked-eye even in quite heavy light pollution -- but it all depends what you mean by "easy." Since you can't meanignfully calibrate the inexperienced but young-eyed you against your current self, there's really no way to tell.

Likewise, having the Milky Way "showing plenty of detail" certainly rules out the brightest skies (Bortle Class 6 or brighter) but leaves a huge amount of wiggle room.

Although I don't think there's any hope of retrieving detailed information on what sky conditions were like, it might be possible to find data on street lighting, which is by far the biggest source of light pollution.

A lesser question that I'm wondering about is "When did it change?" It seems that for many people there was a major shift in light pollution at some epoch -- likely at the time that the location in question changed from being primarily rural to primarily suburban, but perhaps a bit later than that.

For quite a few people, the big shift seems to have happened over the course of the 1970s.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Tony Flanders
Postmaster
*****

Reged: 05/18/06

Loc: Cambridge, MA, USA
Re: Historical Context new [Re: BrooksObs]
      #5912465 - 06/10/13 06:12 AM

Quote:

While your description of the skies you recall is not overly detailed, what you do provide seems to correspond most closely to class 3, or perhaps class 4, conditions on the Bortle Dark Sky Scale (see S&T website under the Resources topic and headed up Saving Dark Skies).




The article in question is at this location.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Tony Flanders
Postmaster
*****

Reged: 05/18/06

Loc: Cambridge, MA, USA
Re: Historical Context new [Re: desertstars]
      #5912556 - 06/10/13 08:18 AM

Organizations that do track light pollution systematically include professional observatories. The history of Mt. Wilson, directly adjacent to the L.A. metropolitan area, is instructive.

Light pollution was not considered to be an issue when the observatory was established in the 1900s and 1910s, but it had become a serious problem by the 1930s. Famously, wartime blackouts enabled Walter Baade to study the core of the Andromeda Galaxy from Mt. Wilson, something that became impossible after World War II.

The site for the Palomar Observatory was explicitly chosen to avoid light pollution.

A Google search for "Mount Wilson light pollution" yielded the following interesting results:

Roy Garstang, 2004

Mount Wilson website

Garstang, of course, is the dean of rigorous light-pollution studies; his paper bears careful reading.

It's interesting that the two sources cited above have opposite conclusions: the Mt. Wilson website claims that light pollution has decreased over the last 25 years due to better ordinances. I would love to see the supporting data!

My own offhand guess would be that light pollution should have remained more or less constant over the last 25 years, since the adjacent area saturated in terms of population density some time ago.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Illinois
Carpal Tunnel


Reged: 12/18/06

Loc: near Dixon, Illinois USA
Re: Historical Context new [Re: Tony Flanders]
      #5912568 - 06/10/13 08:31 AM

Large Pro. Telescope area know about light pollution in 1950's and we don't even think about light pollution in 1950's and 1960's! My late father and I drove to small town near St Louis and the sky is dark. I can see M31 in 1970's and today its orange zone. I remember when I was kid and saw Chicago replaced new streetlights and I said wow! Bright orange light!!!! It was in late 60's or early 70's so at that time the light pollution turn pretty bad!

Post Extras: Print Post   Remind Me!   Notify Moderator  
amicus sidera
Post Laureate
*****

Reged: 10/14/11

Loc: East of the Sun, West of the M...
Re: Historical Context new [Re: Tony Flanders]
      #5912615 - 06/10/13 09:01 AM

Quote:


A lesser question that I'm wondering about is "When did it change?" It seems that for many people there was a major shift in light pollution at some epoch -- likely at the time that the location in question changed from being primarily rural to primarily suburban, but perhaps a bit later than that.

For quite a few people, the big shift seems to have happened over the course of the 1970s.




Indeed, it appears that overall levels of light pollution increased, or at least became more palpable, around that time; from what I saw and heard, the change (at least here in the northeast U.S.) seemed most dramatic in the transition areas (Bortle 4, for example), with many such areas becoming two or even three classes brighter in the space of two years or less. By the mid-1980's the increase in LP seemed to have slowed considerably, at least in these areas.

For example, prior to approximately 1979, the skies above my home (located about 25 miles WNW of Manhattan) met the criteria for Bortle class 4, save for those directly facing NYC; by 1981, conditions had worsened to a Bortle class 6. It then took almost twenty years for them to enter class 7.

While the population in the surrounding area did increase, in my estimation the numbers weren't sufficient for the drastic increase in LP; however, what did increase substantially during this period was vehicular traffic... during this period the local 4-lane state highway went from being a place where one could conceivably take a five-minute evening nap in the fast lane with little chance of being run over, to a steady stream of traffic without letup, even in the wee hours of the morning - this situation has persisted and gradually worsened up to the present day. As Tony has pointed out in posts on other threads on this subject, automobile headlights acccount for a substantial percentage of LP, and I suspect that this increase nighttime traffic accounted for much of the relatively abrupt change in sky conditions during the 1979-1981 period here.

Fred


Post Extras: Print Post   Remind Me!   Notify Moderator  
BrooksObs
professor emeritus


Reged: 12/08/12

Re: Historical Context new [Re: amicus sidera]
      #5912789 - 06/10/13 10:55 AM

I would add to the discussion that most of today's observers were not yet in the hobby, or perhaps not even born yet, when the greatest impact on dark skies occurred. This would have been during the early 1960's with the transition from incandecent to Mercury vapor lighting outdoors. This transition must have marked the end of viable dark skies for fully half the nation's amateur astronomers. It moved the distance to where good skies were found outside moderate to larger cities by at least threefold and probably more. Thereafter, the situation became much more a matter of urban sprawl with its shopping plazas and associated highway illumination to get there. Incidentally, I've never found any noticeable impact from increasing vehicle traffic density, having had a major interstate built just miles south of me back in the 70's.

BrooksObs

Edited by BrooksObs (06/10/13 10:58 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
amicus sidera
Post Laureate
*****

Reged: 10/14/11

Loc: East of the Sun, West of the M...
Re: Historical Context new [Re: BrooksObs]
      #5912905 - 06/10/13 11:58 AM

Excellent points, BrooksObs... The changeover to mercury vapor street lighting, with its greatly increased illumination, certainly had an effect at the time it became generally extant.

My late father traveled extensively on business in the mid-1950's, usually out of Newark Airport, and on DC-6's and Constellations which flew under 20,000'.. he often mentioned that he was able to tell when he was over our small town (pop. <3000 at the time) by its mercury vapor street lights, of which our community was an early adopter... "A greenish glow in a sea of darkness", as he described it. While certainly not the best for astronomy, they were of relatively low wattage compared to the sodium vapor monstrosities which followed them years later; that said, they were certainly a change for the worse from incandescent lamps, as you stated.

As regards the automobile headlight issue, I believe that the addition of even an Interstate highway nearby would not be of too great import in terms of LP; however, in my area the network of roadways, both major and secondary, is truly staggering, and the increased volume of traffic which I mentioned previously extended to all these arteries.

Fred


Post Extras: Print Post   Remind Me!   Notify Moderator  
desertstars

*****

Reged: 11/05/03

Loc: Tucson, AZ
Re: Historical Context new [Re: Tony Flanders]
      #5914186 - 06/10/13 10:27 PM

Quote:


For quite a few people, the big shift seems to have happened over the course of the 1970s.




Which, as happens, is just when I left the area to live in Phoenix, AZ.

I definitely experienced a big increase in light pollution...


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mxplx2
sage


Reged: 09/12/12

Loc: NE PA USA
Re: Historical Context new [Re: desertstars]
      #5919370 - 06/13/13 07:15 PM

Perhaps the electric power company for the area you have in mind might have records of current power usage and usage for the time period you're interested in, and from the two you could infer the difference in LP between then and now. The percentage of power used for lighting vs. other uses like home appliances would have to be factored in, but they might have that info too. The above might give you a partial picture.

Post Extras: Print Post   Remind Me!   Notify Moderator  
George N
Carpal Tunnel
*****

Reged: 05/19/06

Loc: Binghamton & Indian Lake NY
Re: Historical Context new [Re: Mxplx2]
      #5920536 - 06/14/13 12:41 PM

I've lost the link now, but a few years ago I posted in this forum a link to a popular magazine article on astronomy from the early 1930's that had a paragraph or two about "light pollution", so it was something that at least some folks were thinking about even back then.

Post Extras: Print Post   Remind Me!   Notify Moderator  
BrooksObs
professor emeritus


Reged: 12/08/12

Re: Historical Context new [Re: George N]
      #5920974 - 06/14/13 05:29 PM

The recognition of light pollution extends a lot further back than that, George. Shortly after the turn of the last century the little town of Geneva, NY, began installing gas street lighting. Geneva was also the location of Smith Observatory, the facility used by the great comet hunter William R. Brooks. He wrote a letter to I believe it was Popular Astronomy magazine which they published in their letters to the editor pages. Therein Brooks laments the degradation of his formerly pristine skies as a result of illumination from the newly installed street lights. If only Brooks could see what we must put up with today!

BrooksObs


Post Extras: Print Post   Remind Me!   Notify Moderator  
Tony Flanders
Postmaster
*****

Reged: 05/18/06

Loc: Cambridge, MA, USA
Re: Historical Context new [Re: George N]
      #5921725 - 06/15/13 05:17 AM

One of the Springfield Telescope Makers members told my uncle that when James Hartness (the money behind the STM) ran successfully for governor of Vermont in 1921, one of his slogans was "keep Vermont dark."

Hard to imagine anybody using that slogan today!


Post Extras: Print Post   Remind Me!   Notify Moderator  
C_Moon
Pooh-Bah
*****

Reged: 10/23/09

Loc: Beneath the arms of Cassiopeia
Re: Historical Context new [Re: Tony Flanders]
      #5921945 - 06/15/13 10:15 AM

Quote:

One of the Springfield Telescope Makers members told my uncle that when James Hartness (the money behind the STM) ran successfully for governor of Vermont in 1921, one of his slogans was "keep Vermont dark."

Hard to imagine anybody using that slogan today!




Wow, nothing would make me more "bipartisan" than that. Raise my taxes, reduce my health care, I don't care, just so long as you keep the skies dark


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1


Extra information
0 registered and 2 anonymous users are browsing this forum.

Moderator:  LivingNDixie, richard7 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 754

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics