If you visit the National Museum of Natural History in Washington, D.C., one of the exhibits you’ll come across is a map of the Earth, which shows lights detected by satellites at night. With even a cursory look, it’s clear the lights pick out spatial patterns of urban and economic development. Look at the USA, and you see the coasts are brightly lit, whereas the country’s interior is much less so. Look at the Korea peninsula and you see that whilst South Korea is almost ablaze with light, the North is noteworthy for its almost complete absence of light.
The potential ability of night-time lights imagery to detect spatial patterns of urban and economic development has been known in the remote sensing community since the late 1970s. However, it has only recently been brought to the attention of economists following a paper by Vernon Henderson, Adam Storeygard and David Weil entitled “Measuring Economic Growth from Outer Space.” This paper alerted economists to the strong correlation between a country’s rate of GDP growth and the growth in intensity of its night-time lights, and the fact that the lights represent (for economists) a relatively untapped dataset with global coverage and a time-series dating back more than twenty years.