A new family of signals reads activity from the light a country gives off at night, seen from space the same way everywhere.
What it is
The VIIRS instrument on the NASA/NOAA Suomi NPP satellite photographs the whole planet at night, around 1:30 a.m. local time. NASA's Black Marble team corrects each night for moonlight and the atmosphere and combines the clear nights of each month into one picture with pixels about 500 m across (product VNP46A3). Palanor averages that picture over each country's land.
- Night lights (nightlights.radiance.<country>, for example nightlights.radiance.ukr): the average night-time radiance over the country's land, in nW/cm²/sr.
- Change from a year earlier (nightlights.radiance.<country>.yoy): the same month a year before, in percent. This is the one to watch, because it removes the seasons.
- The Gaza Strip and the West Bank (nightlights.radiance.gaza, nightlights.radiance.west_bank) have their own series; Palestine (nightlights.radiance.pse) is both.
- Regions (nightlights.radiance.world, .eu, .sub_saharan_africa and the other Palanor regions): the land-weighted average of their countries with reliable coverage.
How to read it
Light follows electricity, settlement and economic activity. It falls within weeks when power is cut by war, a disaster or a fuel shortage, and it rises with electrification and growth. Compare a month with the same month in other years: snow, leaves and holidays change the light through the year, and single months move with cloud, fires and moonlight. A large country with a dark interior reads low because most of its land is unlit, not because its cities are dim.
It is not a measure of output. LED street lighting and efficiency change it without any change in activity, and gas flares, wildfires and lit fishing fleets add light that is not the economy.
Coverage
NASA builds each month from clear, snow-free nights. Where a pixel had none, NASA fills it with its latest good value; Palanor keeps those filled pixels so that a snowy or cloudy month is not read from its brightest, clearest places alone. A month is published only when pixels observed that month cover at least half of a country's land (and observed plus filled pixels at least 80%), and the share filled is stored with each reading. Only light at or above 2 nW/cm²/sr counts: from 2022 many monthly pictures carry a faint glow over empty land (likely airglow, which strengthens near the peak of the solar cycle), and counting it would make large, dim countries look several times brighter than they are. Countries whose coverage is unreliable all year are not published: high latitudes have no darkness in summer, and heavy winter snow hides others. Very small places are also left out, because a few bright sites swing them. Those series still exist, privately, and the coverage of each reading is stored with it.
Boundaries are Natural Earth's de facto lines, with Crimea counted in Ukraine as in ISO 3166.
Where to find it
Every published country has a night-lights line in its Country Dossier and a layer on the World view map. The Charts library has the world at night and the change from a year earlier (both play as a timelapse from Download → Video), Ukraine since the invasion, Gaza since October 2023, Puerto Rico after Hurricane Maria and the change by region. Search "night lights" in the Library.
Sources
NASA Black Marble VNP46A3 (doi:10.5067/VIIRS/VNP46A3.002), LAADS DAAC. NASA Earth science data have no restrictions on use (CC0); NASA does not endorse Palanor's calculation. Boundaries: Natural Earth (public domain). Each month arrives about three weeks after it ends.
Related: [Charts](/help/modules/charts)