TRANSPARENCY & DATA
About this map and its data
How the light pollution map is built, what its numbers mean, and where the data comes from.
Current data status
ANNUAL SATELLITE LAYER
2024
The most recent complete NOAA VIIRS annual composite available via Google Earth Engine at the time this map was built. Updating to a newer year requires a source-code change — this map does not refresh on a schedule.
How the map is produced
01 · Satellite input
NOAA's VIIRS Day/Night Band annual composite provides the raw artificial-light radiance for every point on the map.
02 · Sky-brightness model
A simplified logarithmic formula converts that radiance into an SQM-like brightness value. This is a deliberately simplified approximation — not the real atmospheric radiative-transfer model that professional light-pollution atlases (e.g. Falchi & Cinzano's World Atlas) use.
03 · Public interpretation
SQM is the more precise comparison value. Bortle class is a simplified, commonly-cited reference derived from that modeled brightness — not a direct field observation.
Important limits
Actual observing conditions also depend on clouds, aerosols, snow, moonlight, temporary lighting, terrain, and local obstructions. A modeled value should not be treated as a live field measurement or a guarantee of visibility. For trip planning, combine this map with its built-in weather, moon-phase, and clear-nights tools and, where possible, an on-site check.
Other estimates on this map
The nighttime weather score, exposure calculator, clear-nights climate stat, and directional sky brightness chart are all clearly-labeled simplified estimates built from free public data (Open-Meteo, NOAA) — not precise forecasts or measurements. Each one explains its own approximation where it's shown.
Sources and references
- • NOAA VIIRS annual nighttime-light composite — primary light-pollution input.
- • The Bortle Dark-Sky Scale — public reference for the classification shown on the map.
- • Open-Meteo — free weather forecast and historical archive API, powers the nighttime weather and clear-nights features.
- • NOAA Space Weather Prediction Center — OVATION aurora model, powers the aurora probability layer.
- • HYG star database (Hipparcos/Yale/Gliese-Jahreiss, CC BY-SA 4.0) — position and magnitude data for the ~8,900 naked-eye stars on the star map page.
- • d3-celestial (Olaf Frohn, BSD-3-Clause) — constellation line figures and bilingual names on the star map page.
- • Astronomy Engine (MIT) — the library computing Sun/Moon/planet positions and sidereal time on the star map page.
Feedback and contact
Questions, corrections, or feedback are welcome by email.
Email: morning.seven.77.77.77@gmail.com