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Earth at Night

  • Written by  Benjamin Hennig
  • Published in Mapping
Earth at Night Benjamin Hennig
08 Aug
Benjamin Hennig maps our illuminated earth by night

Some of the most iconic views of our planet have been made from space. Satellite images continue to amaze us with their unique perspectives that most of us will never experience by ourselves

The so-called Blue Marble, a photograph of Earth taken by astronauts in 1972, became a symbol for environmental activism showing ‘our planet’s frailty, vulnerability, and isolation amid the vast expanse of space’. 

The Earth at Night is a much more recent image, not taken by a human in space, but taken by satellites as a series of several separate post-processed images that provide a consistent clear sight of the night views of all human and natural matter that glows and can be sensed from space. The most recent composite image released by NASA in 2012 uses data acquired by a sensor on the Suomi NPP satellite which ‘detects light in a range of wavelengths from green to near-infrared […] to observe dim signals such as city lights […]’

Reminiscent of the famous Blue Marble 40 years earlier, the Black Marble of 2012 is an equally iconic display of human activity on our planet, which in many parts of the world does not even halt when night falls. What NASA’s image cannot show, however, are the stark differences between those who do have lights and those who that live without any lights at all at night.

The above gridded equal-population cartogram shows the satellite image resized according to how many people live in an area. Depopulated areas disappear, while the map gives the most densely populated areas the most space. The world’s largest city regions such as the Nile Delta in the north-east of Africa, or the Pearl River Delta in the south-east of China become visible in stunning detail. Even single cities, such as Moscow, clearly stand out as if a magnifying glass were being put over them.

More sobering are the differences between the illuminated – or light-polluted – night skies in much of the wealthy world (such as Europe and North America), while the poorer parts of the planet appear as dark areas (as on much of the African continent).

The so-called emerging economies, most prominently China and India with their large populations, are characterised by much more of a patchwork of bright and dark areas.

In 2007 nature conservation organisation WWF initiated the Earth Hour campaign ‘encouraging households and businesses to turn off their non-essential lights for one hour to raise awareness about the need to take action on climate change’. Earth Hour can be a reminder of what a unique planet we live on and that it should take more attention than switching off the lights one evening a year to remind ourselves of the fragility of the blue marble that is far from being a black one at night. Reflecting on our wasteful use of energy in the brightest spots shown in this map is only the start for living a more sustainable future.

This image is the real Earth at night, the world of people that can afford to waste light and shine up into space, and of those who are having no light at night, sometimes by choice, but much more often without. This Earth at Night is much more than just a gorgeous image of where humans are active. It is an iconic reminder of the unequal frailty, vulnerability, and isolation of the poor amid the vast expanse of over seven billion people that now populate this planet.

Benjamin Hennig (@geoviews) is a senior research fellow in the School of Geography and the Environment at the University of Oxford, is part of the Worldmapper project and runs the visualisation blog www.viewsoftheworld.net.

This article was published in the August 2015 edition of Geographical Magazine

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