Thursday, April 27, 2017

The Ever Changing World at Night

The lights are going on all over India. A lot of them. If you compare NASA's new nighttime map of the Earth with the 2012 map you can see where in the world electric lighting has grown and where it has fallen over the last four years. India stands out as a country that has seen a huge increase in night lights,

Two weeks ago NASA released a new composite map showing the Earth at night. 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. If you want you can view the new Black Marble map on NASA's Worldview interactive map.

John Nelson has compared NASA's 2012 and 2016 Black Marble maps to see where in the world lights have been going on and where they have been going off. He has even created his own map, Lights On & Lights Out, which 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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