Cities in the Dark

“When we look up at night and view the stars, everything we see is shining because of distant nuclear fusion.”
– Carl Sagan in Cosmos: A Personal Voyage, 1980

It is Friday and soon weekend, so here is a post on a bit lighter touch than we usually publish on this blog, or maybe not so light?

Sun map

The Earth orbits the sun from an average distance of 149.6 million kilometres and the existence of nearly all life on Earth is fuelled by light from the sun. Most plants use the energy of sunlight, combined with carbon dioxide and water, to produce simple sugars, a process known as photosynthesis. These sugars are then used as building-blocks and in other synthetic pathways that allow the organism to grow.  Animals, such as humans, use light from the sun indirectly by consuming plants or by consuming other animals who live on plants. We also need light to see and find our way around, as most animals have developed eyes that require visible light to see our surroundings.

Many people find direct sunlight to be too bright for comfort. Indeed, looking directly at the sun can cause long-term vision damage. To compensate for the brightness of sunlight, many people in the modern age wear sunglasses. Cars, many helmets and caps are equipped with visors to block the sun from direct vision when the sun is at a low angle. Sunshine is often blocked from entering buildings through the use of walls, window blinds, awnings, shutters, curtains, or nearby shade trees.

noao_solar_eclipse_002-CREDIT-NSO-AURA-NSFBut let us consider how a world would be without sunlight? There would still be ambient light, as there are billions of other stars than the Sun in the Universe, although the light from them is weaker as they are at unimaginably far distances from us. During the night, we can see billions and billions of stars seen from here on Earth. But with every passing day, increasing light and air pollution from growing cities diminishes our ability to observe the cosmos.

The French artist Thierry Cohen draws attention to this creeping loss in his series Villes éteintes (Darkened Cities), which imagines the world’s largest cities under clear night skies. His photographs, which he started to make in 2010, are as impossible as they are beautiful. The dark urban landscapes and vibrant constellations are composites of two images, one of the city and one of the sky.

The images portray cities as they would look if there would be no sun and we had only the ambient light from the stars. He does this by capturing the image of a city, documenting the precise time, angle, and latitude and longitude of his exposure. by noting the precise latitude and angle of his cityscapes, he then tracks the earth’s rotation to places of atmospheric clarity like the Mojave, the Sahara, and the Atacama deserts, setting up his camera to record how the sky looks from there. He then combines the two images, creating a single new image full of resonance and nuance.

The work is both political and spiritual, questioning not only what we are doing to the planet but drawing unexpected connections between disparate locations. Equally importantly it asks: what do we miss by obscuring the visibility of stars by the air pollution and street lights?

As the world’s population becomes increasingly urban, there is a growing disconnect between the natural world  and the artificial world of our cities, where the urban landscapes that never sleep are made up of millions of individuals breaking natural cycles of work and rest. The photographic series attempts to restore our vision, hoping to re-connect users to the infinite energy of the stars. Cohen’s work is displayed in photo galleries across the world and if you have a chance, I recommend you to see them. The images in real life are even more powerful than online pictures.

Below are some of Cohen´s pictures of famous sceneries in well-known cities. Do you recognize where they are from? You can click on the images to see a larger version, and go to Cohen´s homepage in this link to see more.


Paris 48° 50’ 55’’ N 2012-08-13 lst 22:15

New York

New York 40° 44’ 39’’ N 2010-10-13 lst 0:04

San Francisco

San Francisco 37° 48’ 30’’ N 2010-10-09 lst 20:58


Shanghai 31° 14’ 39’’ N 2012-03-19 lst 14:42

Hong Kong

Hong Kong 22° 17’ 55’’ N 2012-03-23 lst 14:54

Los Angeles

Los Angeles 34° 03’ 20’’ N 2010-10-09 lst 21:50

Rio de Janeiro


Luckily, we can see the world without sunshine in artistic images like this and we do not have to endure it in real life. If the Sun would disappear, for us on Earth, the consequences would be pretty harsh. On the positive side, our planet retains heat rather well, so we would not freeze to death instantly. Also, as light from the Sun takes eight and a half minutes to reach us, we would have a final few moments of final sunshine before our planet was bathed in darkness.

Those currently on the night side of the Earth would not notice much difference until, a few seconds after day-dwellers were thrust into darkness, the Moon suddenly disappeared as it no longer had the Sun’s light to reflect. The other planets of our solar system would follow, disappearing one by one as the wave of darkness reached them.

Eventually, the lack of the Sun’s radiation would leave us freezing. Just think about how much colder it is at night time rather than the day, but imagine that same temperature drop constantly occurring. Within days the world would be a hundred or so degrees below the freezing point, and within weeks it would be just 50 or so degrees above absolute zero ((minus 273.15 degrees Celsius). The atmosphere itself would freeze and fall to Earth, leaving us exposed to the harsh radiation travelling through space and without air to breathe.

Life as we know it would have to adapt to survive to our new frozen Earth, and it’s likely only microorganisms beneath the surface could survive thanks to heat from the core. For humans, we would probably have to pool together and build a few nuclear fusion reactors in order to last a while, if we had the time to do so. Darkness would also block usage of The Moser Lamp, which we have written about here before.

These are thoughts worth considering, as we continue to pollute the earth on a daily basis. Sensible innovations, focus on sustainability and economic incentives through legislation and international agreements that steers the markets to environmentally friendly usage of resources can maybe turn the negative trends. Maybe.

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