Population density × median age for the whole planet — every inhabited square kilometre, brightness by density, color by the median age of its residents. Click anywhere for that cell's exact WorldPop age pyramid.
Caveats. WorldPop models age structure from each country's most recent census, disaggregated by satellite-mapped settlement — density is genuinely ~1 km, but age structure is typically uniform within census admin units, so effective age resolution is district-scale. Census vintage varies by country. For counted (not modeled) block-level truth, see the Japan map. Median within a cell is interpolated inside 5-year bands; 80+ treated as 80–100.