The need to look up at the night sky has united people for centuries and rarely are we able to look down upon ourselves in the stark detail seen in Nasa's latest satellite imagery.
Called Black Marble, the interactive map combines composite shots from Nasa's satellites, showing points of nighttime illumination across the globe and tracking how they've changed in recent years.
The last major satellite composition of this kind was collected in 2012. Since then it's become clear certain areas of the globe have either grown, or dwindled drastically, in terms of light intensity. Using cloud-free images, collected throughout 2016, the strongest lights can be seen to centre around populous cities, as would be expected. London, Paris and Alexandria remain points of strong light focus, with the river Nile illuminated as it spreads down from the Mediterranean sea. These points haven't significantly changed since the 2012 data collection, but overall, European countries have seen a decrease in light intensity at night. This could be due to the signing of the Paris Agreement and overall efforts to conserve energy.
While there hasn't been a significant change to the light intensity of the United Kingdom, we have seen a slight increase in light usage at night – particularly centred around Birmingham, for reasons that are unclear.
Some areas of the map reflect political or economic changes. A struggling economy and an effort to reduce light pollution have dimmed Puerto Rico, for example, similar to how nationwide dimming has resulted from Venezuela's economic depression.
John Nelson's accompanying map 'Lights On / Lights Off' explains some of these changes. "Lights on" are represented in blue, whereas lights dimmed or altogether extinguished are seen in pink. An area of significant change can be seen in Syria where there has been a dramatic decrease in light at night, particularly in centres and around transport routes. Nelson describes it as a sign of "the collapse of population and infrastructure due to war and upheaval". The lack of light is, in this case, a symbol of destruction.
In contrast, India, which has experienced increased electrification throughout many of the northern regions, has lit up – marking a new stage in the country's energy usage. Nelson describes these nuanced differences in light intensity as an expression of larger changes: "The switching on or off of nighttime lights represents both optimism and newness as well as violence and loss," he says.
With the creation of the first Black Marble in 2012, Chris Elvidge, a National Oceanic and Atmospheric Administration scientist said: "Nothing tells us more about the spread of humans across the Earth than city lights." As such, the night lights collected in 2016 tell us about human journeys – of migration, loss and prosperity. It is a tale told in minutiae, one in which we are unable to see the people whose lives are reflected in these lights, but whose stories are written across the landscape.
This article was originally published by WIRED UK
