Night Lights: South America, Change vs Year Earlier (%)

## What this measures

The percent change in South America's average night-time light (nightlights.radiance.south_america) from the same month a year earlier, from NASA's Black Marble satellite record.

## Why it matters

Comparing with the same month removes the seasons, so the change shows whether South America is brighter or darker at night than a year ago: electrification and growth on one side, war, blackouts and fuel shortages on the other.

## How to read it

Above zero means brighter than a year earlier. Read several months together: single months move with cloud cover and fires.

## 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

The month's value of nightlights.radiance.south_america divided by the same month a year earlier, minus one, in percent (12 countries with reliable coverage, holding 99% of the region's land). From January 2013.

## 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.