NOAA's National Geophysical Data Center

Here is the photo that gives an idea of how we conserve energy on the planet.
The NASA image showing all permanent sources of light in the world. - Mainly street lights in the world's cities.

The image was developed by NASA through the system Defense Meteorological Satellite Program (DMSP) and the Operational Line Scan System (OLS).
Actually, those systems were to investigate and identify clouds at night.
Earth's street lighting
But now NASA has found another use. These systems have mapped the entire world fixed street lights and the areas that use most energy.
The brightest areas are the most urban. But that does not mean they have the most inhabitants.

Western Europe, for example, is almost completely illuminated on the image, while large parts of China and Africa have only a few light bulbs.
The picture shows the American motorway system as a grid over the North American continent.
And in Russia runs the Trans-Siberian railway as a thin line from Moscow, through Asia to Vladivostok.
But even though the electric light has been in existence for over 100 years, a large region of the earth’s surface is still covered in darkness.

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