Tuesday, May 02, 2017

Changes to the Black Marble

NASA's new composite satellite map of the Earth shows the distribution of artificial lights around the world. The so called 'Black Marble' map of the Earth is made up of the best cloud-free satellite images of each land mass captured during 2016.

The new Black Marble map can also be compared with the last major satellite map that was created to show the Earth at night, released by NASA in 2012. By comparing the two maps it is possible to see where lights have been going on and off around the globe in the last five years.

If you want you can view the new Black Marble map on NASA's Worldview interactive map. Alternatively you can compare the 2012 and 2016 Black Marble maps side-by-side on the Black Marble: 2012 vs 2016 interactive map. This map allows you to swipe between the two NASA maps and compare the changing scale of natural lighting around the world. For example, if you open the map using the link above you can clearly see the effect that the Syrian war has had on electricity supply in the country.

John Nelson has also compared NASA's 2012 and 2016 Black Marble maps to see where in the world lights have been going on and off. His Lights On & Lights Out map highlights the locations around the world where there have been significant changes in electric lighting since 2012.

Nelson points out in the text accompanying the map that there are many reasons why places might show an increase or decrease in electric lighting. The increase in India is due to the "massive electrification of northern India in recent years". Elsewhere reductions in night lighting may be due (among other reasons) to attempts to reduce light pollution.

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