International Dark-Sky Association

Non-Aggression, Floodlights, and the Aging Eye

In our ongoing journey back through the archives of the IDA Information Sheets, here are three more that are noteworthy and still relevant.

IDA Information Sheet 161 – April 2000
IDA’s Approach to People About Bad Lighting

Though this information sheet was produced in the year following my tenure as IDA Information Sheet Editor, I am sure this one was penned by David L. Crawford (1931-), co-founder of the International Dark-Sky Association.

In these hyper-polarized times, Crawford’s advice is even more important than it was in April 2000. Not only for how to talk to someone about their bad lighting, but for talking to anyone about any behavior born out of ignorance or the consumption of misinformation.

I have so many fond memories of hearing Dave Crawford, the good-lighting evangelist, speak. If I recall correctly, his father was a minister, so you can see where he began to hone his exquisite powers of persuasion and his always non-confrontational approach. He never talked down to you. Or over you. He was effective. “Avoid confrontation, even in a crisis mode. Be professional, and calm.” And, “It is critical to speak from knowledge and experience, not just emotion.” Words of wisdom. Even in the worst of circumstances.

IDA-Information-Sheet-161-April-2000 Download

IDA Information Sheet 158 – October 1999
Shielding Floodlights

Bob Crelin, inventor of the phenomenal GlareBuster (sadly, no longer available), and author of the children’s books There Once Was a Sky Full of Stars and Faces of the Moon, wrote this information sheet. What a pleasure it was working with Bob and I treasured our conversations at IDA meetings in Tucson back in the day. I wonder what he is up to these days?

IDA Information Sheet 158 – October 1999 DOWNLOAD

IDA Information Sheet 156 – August 1999
The Aging Eye – Some Basic Information

Dave Crawford wrote this information sheet, and it contains a wealth of information. Notice how he hits the major points multiple times and yet from a variety of angles. Repetition can help us to learn and internalize what we read.

From my own personal experience with “aging eyes”, I am finding it more difficult to drive at the posted speed limit at night. 5 mph less than the posted speed limit is more comfortable, and safer. I drive a low-profile vehicle with normal halogen headlights. But the many aggressive drivers now with high-profile vehicles (SUVs and pickup trucks—those with suspension lifts are the worst) and blindingly-bright headlights (the likes of which we have never seen before) are making night driving increasingly dangerous for the older driver. And there are many of us.

IDA-Information-Sheet-156-August-1999 Download

IDA Information Sheets

I recently received a membership renewal notice from the International Dark-Sky Association (IDA) quoting Christopher Kyba that if light pollution continues to grow at the rate it currently is, “Orion’s belt will disappear at some point.”

This made me remember that I had written an IDA Information Sheet back in March 1997 that also had addressed how light pollution could erase much of the Orion constellation. I wrote,

Orion, arguably the most prominent of the constellations, begins to look more like “Orion, the Hunted” under a magnitude +4.0 sky. Under a magnitude +3.0 sky, Orion is on his deathbed. When light pollution is so bad that we have a magnitude +2.0 sky, only blazing Betelgeuse, regal Rigel, and Bellatrix and Alnilam remain to regale us.

Speaking of the IDA Information Sheets, I was the IDA Information Sheet Editor from 1996-1999, during which time I revised and edited most of the existing information sheets, edited and added many new ones from a number of contributors, as well as contributed many new ones that I authored, though I never credited myself as the author. One of the ones that I wrote was IDA Information Sheet 120, referenced above (and shown below). I have a complete hard copy set of IDA Information Sheets 1 through 175, the last of which was published in June 2000. I also have WordPerfect Macintosh source files for IDA Information Sheets 1 through 158, the last of which was completed on October 27, 1999.

Here’s IDA Information Sheet 120:

IDA-Information-Sheet-120-March-1997 Download

It is a shame that these IDA Information Sheets are no longer available anywhere on the Internet. At the very least, they are of historical interest, and I would say that much of the content is still relevant. Presumably, the IDA still has all of these information sheets, but after the Dave Crawford era, they have decided to remove access to them.

Finally, I want to express my disappointment that the International Dark-Sky Association has recently decided to change their name to DarkSky International. They are still in the process of changing everything over, but once that transition is complete, the IDA will be no more. The break with the Dave Crawford era will be complete. I, for one, will never forget how much Dave Crawford was able to accomplish during those early years, and how proud I was to have been a part of it.

The IDA/DSI is still a great organization, and I strongly encourage you to generously support it, as I do. It remains the most effective organization in the world addressing light pollution and the loss of our night sky and the natural nighttime environment.

Dark-Sky Communities

Back in 2006, I started a Yahoo! Group called DarkSkyCommunities. My goal was to provide a forum for astronomy enthusiasts and other like-minded individuals to discuss living where you’d have a star-filled night sky and never have to worry about streetlights or neighbor’s lights. Everyone else in the community would value the night sky and a natural nighttime environment as you do.

My approach with DarkSkyCommunities was not to be a heavy-handed moderator. I approved new members but after that, members were free to post (within reason) anything they wanted to. In that sense, it worked pretty well and there were very few postings I ever had to take down.

Unfortunately, astronomers know next to nothing about intentional community and intentional communitarians know next to nothing about astronomy, so the group drifted far from my original intent to a general discussion about light pollution, with “what’s wrong with the IDA” being a surprisingly popular topic for discussion. Eventually, though, a small number of individuals with a chip on their shoulder or an axe to grind became the most frequent posters, and that sort of poisoned the group.

So, I’d like to introduce to you DarkSkyCommunities 2.0: a Google group called Dark-Sky Communities. Here’s the description on the landing page:

Dark-Sky Communities is a discussion group for the development and nurturing of intentional communities where the night sky and the nighttime environment are valued and protected. The emphasis is on affordable, sustainable dark-sky communities where those of modest financial means can live, work, and retire. This group is moderated to keep the focus on intentional communities that are astronomy-friendly.

This time around I am going to approve (or disapprove) the messages posted to the group so that we stay on the topic of astronomy-friendly intentional communities. If you have an interest in this topic, please join!

Light pollution, despite our best efforts, is getting worse almost everywhere. LED lighting which had (and still has) so much promise is generally resulting in more lights, brighter lights, and bluer lights—not the direction we want to head.

Someday, I would like to live in a place where I can walk a few feet beyond my door, set down a lawn chair, and watch a meteor shower without being assaulted by streetlights, insecurity lights, glare, and skyglow. Is that too much to ask?

Would you like to live in a place like that, too? Let’s make it happen!

Illumination Levels: Then and Now

The following excerpts are from the 1911 and 1925 editions of A Text-Book of Physics by Louis Bevier Spinney, Professor of Physics and Illuminating Engineering at Iowa State College (now Iowa State University) in Ames, Iowa.

From the 1911 edition…

ILLUMINATION

516. The intensity of illumination of any surface is defined as the ratio of the light received by the surface to the area of the surface upon which the light falls. A unit of intensity which is oftentimes employed is known as the foot candle, and is defined as the intensity of illumination which would be present upon a screen placed at a distance of one foot from a standard candle. The meter candle is a unit of intensity which is employed to some extent.

The table below gives a number of values of illumination such as are commonly observed, the intensity of illumination being expressed in foot candles.

Suitable for drafting table . . . . . 5 to 10

Suitable for library table . . . . . . 3 to 4

Suitable for reading table . . . . . . 1 to 2

Required for street lighting . . . . . 0.05 to 0.60

Moonlight (full moon) . . . . . . . 0.025 to 0.03

And from the 1925 edition…

ILLUMINATION

532. The eye has a remarkable power of adaptation. In strong light the pupil contracts and in weak light expands, so that we are able to use our eyes throughout a range of illumination which is really quite astonishing. However, the continued use of the eyes under conditions of unfavorable illumination causes discomfort, fatigue, and even permanent injury. Experiment and experience show that eye comfort, efficiency, and health considerations demand for each kind of eye work a certain minimum illumination. Some of these illumination values taken from tables recently compiled are given below.

FOOT-CANDLES

Streets . . . . . . . . . . . . . . 1/20 to 1/4

Living rooms; Halls and passageways . . 1 to 2

Auditoriums; Stairways and exits;
Machine shops, rough work . . . . . . 2 to 5

Classrooms; Laboratories; Offices;
Libraries; Machine shops, close work . . 5 to 10

Engraving; Fine repairing work; Drafting;
Sewing and weaving, dark goods . . . . 10 to 20

By comparing the 1911 and 1925 data with the illumination levels recommended today by IESNA, we can see that recommended light levels for streetlighting have increased anywhere from 40% to 380% since 1925. A cynic might say that we need more light than our ancestors did to see well at night. As you may have noticed, light levels have been steadily creeping upward, everywhere, over the last few decades.

Recommended Illumination Levels for Streetlighting

Year Minimum Average Maximum

1911 0.05 ??? 0.60

1925 0.05 0.25 ???

1996 0.07 1.20 ???

Have you ever noticed how well you can see at night when the full moon is lighting the ground? The full moon provides surprisingly adequate non-glaring and uniform illumination at just 0.03 footcandles! For inspiration, take a look at the following text from an Ames, Iowa city ordinance, dated July 8, 1895:

“The said grantees shall keep said lamps in good condition and repair, and have the same lighted every night in the year from dark until midnight, and from 5:00 a.m. until daylight, except such moonlight nights or fractions of the same as are not obscured by clouds, and as afford sufficient natural light to light the streets of said city.”

This was originally published as IDA Information Sheet 114 in November 1996, and authored by David Oesper.