Fontes e licenças

Name: Céu estrelado: probabilidades
License: https://creativecommons.org/licenses/by/4.0/

Quando o céu está limpo, sem Lua e escuro nos parques de céu escuro e nacionais da Europa: horas limpas por mês (ERA5), poluição luminosa, meteoros.

Fontes e licenças

Fonte	Editor	Data dos dados	Licença
ERA5 hourly data on single levels (total cloud cover), via the Open-Meteo mirror on AWS 0.25° grid (≈ 25 km), hourly total cloud cover 2006–2025 in the grid cell of the darkest spot. Neither Copernicus nor ECMWF is responsible for any use of this information.	Copernicus Climate Change Service (C3S) / ECMWF; mirror: Open-Meteo	31 de dezembro de 2025	CC BY 4.0 Cloud climatology: Hersbach et al. (2023), ERA5 hourly data on single levels, Copernicus Climate Change Service (C3S) Climate Data Store; contains modified Copernicus Climate Change Service information 2026; data via Open-Meteo (open-meteo.com, CC BY 4.0).
Open-Meteo open data (ERA5 mirror on AWS, s3://openmeteo) and Historical Weather API Data access to ERA5; the Historical Weather API was used only to check our readings.	Open-Meteo.com	2 de novembro de 2026	CC BY 4.0 Weather data by Open-Meteo.com (CC BY 4.0).
NASA Black Marble VNP46A4 v002 — VIIRS/NPP yearly night-time lights (snow-free composite), 15″ Yearly composite of the latest available year. The sky-glow index is our own (sum of radiance × distance^−2.5 within 100 km); it is not a measurement of sky brightness in magnitudes.	NASA Goddard Space Flight Center / LAADS DAAC	31 de dezembro de 2025	NASA open data, no restrictions Night-time lights: NASA Black Marble VNP46A4 (Román, M.O. et al. 2018, Remote Sensing of Environment 210, 113–143), doi:10.5067/VIIRS/VNP46A4.002, distributed by NASA LAADS DAAC; light-pollution index computed by us.
Wikidata — national parks and dark-sky places (coordinates, area, OSM link, names)	Wikimedia Foundation	2 de novembro de 2026	CC0 1.0 Place names and coordinates: Wikidata (CC0).
OpenStreetMap — boundaries of parks and reserves (via Overpass API)	OpenStreetMap contributors	2 de novembro de 2026	ODbL 1.0 Park boundaries © OpenStreetMap contributors, ODbL.
DarkSky International — list of International Dark Sky Places Only the fact of designation, its type and country are used; coordinates come from Wikidata or OpenStreetMap.	DarkSky International	2 de novembro de 2026	Facts (names and designation types only) International Dark Sky Place designations: DarkSky International (darksky.org).
International Meteor Organization — Meteor Shower Calendar and Working List (solar longitude of maxima, radiants, ZHR)	International Meteor Organization (IMO)	2 de novembro de 2026	Facts (peak solar longitudes and radiant positions) Meteor shower maxima and radiants: International Meteor Organization (imo.net); peak times computed by us from the IMO solar longitudes.
JPL planetary and lunar ephemeris DE440s, computed with Skyfield	NASA Jet Propulsion Laboratory; Skyfield (Brandon Rhodes)	1 de fevereiro de 2021	Public domain (JPL); Skyfield MIT Sun and Moon positions: JPL DE440s ephemeris (NASA JPL) computed with Skyfield.
Cerema — national map of night-time public lighting practices (municipality level, VIIRS 2014–2025) Classes and break months per municipality, mean VIIRS radiance per month 2014–2025. Overpass times measured by us (144 Suomi NPP / NOAA-20 passes in 2025).	Cerema, with DarkSkyLab and OFB	15 de junho de 2026	Licence Ouverte 2.0 Street-lighting practices: Cerema, national map of night-time lighting practices (method developed with DarkSkyLab and OFB), data.gouv.fr, Licence Ouverte 2.0.
NASA Black Marble VNP46A3 (monthly) and VNP46A1 / VJ146A1 (daily) — overseas departments, read by us Overseas departments (971–976): UTC_Time layer of daily VNP46A1 (Suomi NPP) and VJ146A1 (NOAA-20) on the 15th of each month of 2025, two towns per territory → local overpass time; monthly VNP46A3 2014–2025, AllAngle_Composite_Snow_Free and its _Num layer (number of cloud-free night observations) over the lit pixels of each municipality (VNP46A4 2025 ≥ 5 nW/cm²/sr).	NASA Goddard Space Flight Center / LAADS DAAC	31 de dezembro de 2025	NASA open data, no restrictions Overseas overpass times and cloud-free nights: NASA Black Marble VNP46A3 / VNP46A1 / VJ146A1 (Román, M.O. et al. 2018), NASA LAADS DAAC; read by us.