Wednesday, July 2, 2014

Light Pollution Is Blotting Out the Stars

As I have written, our moderncentric point of view  makes it hard to understand some simple basic facts about the history of human development. 

For example, until several hundred years ago virtually all towns and cities, large and small, were dark at night -- quite dark. Nevertheless, even with the introduction of street lighting in Paris and London about 300 years ago, the candle lamps were dim and only on main roads. And although cities became better lit by the 19th century, these lights did not wash out the sky until recently -- about 50 years ago.

While doing research for my blogs, I realized that our ever present electric lighting has blinded us to the fact that for most of human history, we humans had a clear view of the stars at night -- no matter where we lived. Interest in the stars and constellations goes back tens of thousands of years -- possibly hundreds of thousands of years. This means that until the rise of the modern well lit world, the stars were familiar and important to the average person -- whether a cave dweller in Paleolithic times, a Roman in the Roman Empire or a Victorian in London. 

Even using conservative estimates, our modern lighted environment has been part of the human lifestyle for about 1/10 of 1% of the life of our species -- i.e., only 300 years of the last 200,000 years since we (homo sapiens sapiens) evolved.

As I have written I believe Paleolithic people would have been able to read the stars like a sacred book, a book they had seen since birth. However, modern scholars often dismiss this idea -- in part because they are unfamiliar with the night sky, blinded as they are by the bright lights of today.

This is important because it is my belief that the original clock and calendar were  based on the stars, the moon, the planets and the constellations. Yet many assume that once the great cities of Rome and Greece had risen, the streets were somewhat well lit and consequently people paid much less attention to the night sky. But this is totally false.

No less an authority than the British Museum had this to say about ancient Greek culture in their "Summary of the Greeks' relation to the stars:"
"The stars were used as gigantic clocks to measure the changes in the seasons."
My Point Is This 
For most of history people had a clear view of the stars and the moon which were a point of reference -- a nightly clock and a monthly, seasonal and yearly calendar. Also because the cities were not lighted, people's eyes were often well adjusted to seeing in the dark -- and so the night sky was an ever present background. NOTE: This fact is critical because eyes that have adjusted to darkness can see many more stars. 
Yet, our picture of ancient times is often quite different. 


Our moderncentric view has been shaped in part by paintings and Hollywood movies. We think historic cities were not dark because the movies have shown us well lit nighttime scenes. Yet the night images we saw in such movies as Ben Hur and Gladiator and the paintings beginning with the 16th century were not realistic.

In the fictional historic worlds created by Hollywood, light seemed to be everywhere. So in this screenshot from the trailer for the 1951 film Quo Vadis (left) Deborah Kerr was seen in light that illuminated the background and delicately highlighted her face -- all from Roman lamps! In reality the light was probably more like the picture on the right, where the background was dark and her face was lit in a much starker manner. ( NOTE: The picture on the right is my own reworking of the original trailer screenshot and my best guess about the actual lighting in ancient Rome.

Depictions of historic time periods often show bright lamps and candles that illuminate wide areas. Yet this is not accurate. While this may seem like a minor point, it is not. As a photographer, I know how light operates. Light diminishes according the to square of distance, which means that light falloff is quite rapid.

Quote from Wikipedia: "The intensity (or illuminance or irradiance) of light or other linear waves radiating from a point source (energy per unit of area perpendicular to the source) is inversely proportional to the square of the distance from the source; so an object (of the same size) twice as far away, receives only one-quarter the energy (in the same time period)." ( 

This is a completely unrealistic painting in terms of lighting. In this painting one candle is brightly shining on the man in the bed and the two women several more feet away. The intensity of the light does not change with the distance from the candle. It is images like these that have given us a false picture of how light operates. (

This is a much more realistic picture of how light works. The torch on the left illuminates the person it is closest to and then the light falls off rapidly as the distance increases. (

If we want a realistic understanding of people in the past, we need to know that they spent much of their time in near darkness -- a darkness they were accustomed to and that they understood. 

So just how dark were the cities? Let's take ancient Rome as one example.
This is in fact one of the characteristics which most markedly distinguishes Imperial Rome from contemporary cities: when there was no moon, its streets were plunged in impenetrable darkness. No oil lamps lighted them, no candles were affixed to the walls; no lanterns were hung over the lintel of the doors, save on festive occasions...Jerome Carcopino, Daily Life In Ancient Rome: The People And The City At The Height The Empire 

Roman bronze oil lamp. Oil was poured into the filler hole in the middle and the wick came out of the nozzle. (
But in addition, the illumination that did exist was from a variety of oils (olive, fish, sesame, whale and nut oils, for example) used in lamps, then later from candles and even later from kerosene. All of these created light in the red end of the spectrum. Candle light, for example, is 1,850 K putting it in the far red end. 

As I mentioned in an earlier blog faint red light does little harm to night vision -- meaning that people would have been able to see the stars clearly on a nightly basis, with little or no adjustment needed. As a result the night sky was not just background or unimportant, but something people paid attention to. Like today's celebrity stars, I suspect Romans discussed the movement and changes in the heavenly stars and planets just about every day and educated citizens commented on anything unusual -- not unlike our news stories now. 

And how about the cities of Europe after ancient times?

Around 1590 probably in London, Shakespeare wrote the following, showing that he had a clear view of the night sky -- one that his theater audience would be familiar with:
The poet's eye, in a frenzy rolling,
Doth glance from heaven to earth, from earth to heaven;
And as imagination bodies forth
The forms of things unknown, the poet's pen
Turns them into shapes, and gives to airy nothing
A local habitation and a name. 
William Shakespeare, 
A Midsummer Night's Dream, circa 1590

Candles became widely available in Europe around the 13th century.  In the 17th century cities began to install candle street lights.
"In 1667, Paris became the first city in the world to light its streets, using wax candles in glass the end of the century, more than 50 of Europe's major towns and cities were lit at night." Quoted from the URL next.
While street lighting began in Paris in 1667, it was only from November to March and only on main streets. Yet by 1700 it had been extended to nine months of the year. The idea of street lighting with candles spread to other cities, yet many only lit their lamps on moonless nights. And although candles helped, the general lighting was still quite dim.
Information paraphrased from: 
Joan DeJean, How Paris Became Paris: The Invention of the Modern City

A painting of Frederick the Great of Prussia playing the flute. While the best quality approx. 50 candles -- pictured here in the mid-18th century -- were a lavish expense, the total light output was about as much as one 100 watt incandescent bulb of today. (

Although there were street lamps in major cities, they were quite faint. London was so dim in the early Victorian era that boys called link-boys (bottom left) made a living by carrying a candle or torch at night to guide people to their destination. The picture above is of a woman arriving home in her 'sedan chair' -- with a street lamp behind her, a footman with a candle and a link-boy with a torch. Picture of contemporary London life from Dicken's Pickwick Club 1837. (

Another unrealistic painting. The bright light for this well lit coffee house comes from only a couple of candles. (

Gas lighting in Paris in 1889. Gas lighting became common by the end of the 19th century. Yet although brighter than candles, it was relatively dim compared to today's electric lights and also burned in the red end of the spectrum. So the stars and the night sky were still visible in the 19th century and were an integral part of people's lives up until a few years ago. Countrywide electric lighting did not take over until after World War II. (


Today in just about any city of any size, electric lights blot out the sky. Even in the country area-lights have begun to take over. Light pollution is everywhere. As a result the stars of the night sky are lost to us. 
Google translation from the French Wikipedia entry about light pollution: With the emergence and rapid spread of the light bulb and the electric network, public lighting became widespread in the world, producing in the 1940s an early bright halo, reported by astronomers as being a hindrance to their work. The concept of "light pollution " was born (under that name) in the late 1980s.
Today few people know the constellations or keep track of the phases of the moon or are aware of the summer or winter solstice or the spring or fall equinox -- things that were essential to our ancestors for hundreds of thousands of years. The stars and moon were the original clock -- one that we have exchanged for an artificial man-made system of timekeeping that is virtually removed from the natural cycles of the Earth.

Here is a quote from a discussion group about why astronomy is not important:
Science & Mathematics > Astronomy & Space
I think that most people are focused on a few things that are critical to their own existence. For some, that means family; for others, a career. In those specific areas, they are generally articulate and knowledgeable...What this means is that astronomy is a backwater in the knowledge pool for most folks. They could understand it if it was a priority, but it's not. 
If we wonder why so many urban people today feel alienated, one reason could be that they are no longer in touch with the cycles of the Earth and the Sun and the natural sense of time told to us by the stars.

Coney Island's Luna Park, an amusement park in New York City at the beginning of the 20th century (1903), when electric light was still a novelty. (

 NYC around 1935 from the top of a construction site. (

 Times Square today in NYC. (

Satellite composite of lights at night on the Earth. (

Map showing light pollution in Europe: red is the most, yellow next. (

 The same region of sky near a town of about 200 people (top) and near a city of about 400,000 people (bottom) in Utah, USA. The light pollution near any urban area now blots out much of the sky. (

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