Night Lights: Ukraine (NASA Black Marble, monthly)

## What this measures

How brightly Ukraine's land shines at night each month, seen from space by the VIIRS instrument on the NASA/NOAA Suomi NPP satellite and processed by NASA's Black Marble team (product VNP46A3). The value is the average radiance of its land in nanowatts per square centimetre per steradian (nW/cm²/sr).

## Why it matters

Light at night follows electricity, settlement and economic activity, and it can be seen the same way everywhere. It falls within weeks when war, a disaster or a fuel shortage cuts power, and it rises with electrification and growth, so it is an independent check where official figures are late, revised or missing. In November 2022, a month after Russian strikes on Ukraine's power system began, the reading was 61.9% below November 2021.

## How to read it

Higher means more light. Compare a month with the same month in earlier years (nightlights.radiance.ukr.yoy does this): light moves with the seasons (snow, leaves, holidays) 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.

## What it does not say

Light is not output. LED street lighting, efficiency and curfews change it without any change in activity, and gas flares, wildfires and lit fishing fleets near the coast add light that is not the economy. The satellite passes at about 1:30 a.m. local time, so it sees what stays lit after midnight, not the evening peak. Faint light from moonlight and the atmosphere is corrected but not perfectly, and cloud cover changes which nights a month is built from.

## How it's built

Each month NASA composites every night's moonlight- and atmosphere-corrected radiance into one value per pixel (about 500 m across) from clear, snow-free nights (the "snow-free, all angles" composite). Where a pixel had no such night that month, NASA fills it with its latest good value (its "gap-filled" flag); Palanor keeps those pixels, so a snowy or cloudy month is not read from its brightest, clearest places alone. Only light at or above 2 nW/cm²/sr counts: from 2022 many monthly composites carry faint background light over unlit land, just above the 0.5 that NASA cuts to zero, and counting it would lift the readings of large, dim countries several times over. The value is that light summed over the land, each pixel weighted by its true area, divided by the land with a value. A month is published only when pixels observed that month cover at least 50% of the land and observed plus gap-filled pixels at least 80%; the shares observed, gap-filled and lit are stored with each reading. Pixels count when their centre lies inside Ukraine's Natural Earth 10m boundary (589,300 km² of land on NASA's land/water mask). Ukraine includes Crimea, as in ISO 3166-2:UA (Natural Earth's de facto line puts it in Russia). NASA posts each month about three weeks after it ends; history from January 2012.

## Source

NASA Black Marble VNP46A3, collection 2 (VIIRS/NPP Lunar BRDF-Adjusted Nighttime Lights Monthly L3 Global 15 arc-second, doi:10.5067/VIIRS/VNP46A3.002), from NASA's LAADS DAAC. NASA Earth science data have no restrictions on use or redistribution (CC0). Boundaries: Natural Earth 10m (public domain). Palanor calculation; NASA does not endorse it. Refreshed by /api/cron/nightlights-publish from a GitHub Actions job that reads only the radiance, quality and land layers and stores no imagery.