This page lists where WhichPhase's weather, mapping, and astronomical data comes from, and how astronomical events are verified before they're published.
WhichPhase uses Open-Meteo weather systems to help provide:
Open-Meteo may incorporate multiple forecast models and globally respected weather systems, including major international forecasting sources such as European forecasting models, to help improve planning reliability.
Weather forecasting is highly useful, but weather can still change quickly due to storms, terrain, elevation, wildfire smoke, coastlines, and local microclimates. Forecasts are estimates, not promises.
WhichPhase uses SunCalc calculations to estimate:
Sun, moon, and light timing calculations are generally reliable for planning, but visible real-world conditions may still be affected by cloud cover, smoke, mountains, haze, or atmospheric conditions.
WhichPhase uses Nominatim and OpenStreetMap geographic systems to help identify:
These systems help tailor weather, moon, and light calculations to specific locations. Search precision may vary depending on rural areas, mapping conventions, and regional naming systems.
WhichPhase may use Open-Meteo elevation estimates to support:
Elevation can vary dramatically within broader areas, especially in mountainous or uneven terrain. Local conditions may differ significantly from generalized area estimates.
For supported U.S. regions, WhichPhase may surface severe weather alerts using NOAA public alert systems.
Users should always rely on official emergency management, NOAA, local authorities, aviation systems, marine alerts, wildfire systems, avalanche centers, and ranger guidance for safety-critical decisions.
WhichPhase includes Light Mode, Dark Mode, and Ultra Dark Mode to support different real-world visibility conditions.
These display modes do not change the underlying data, but they improve practical usability depending on environment, time of day, and planning conditions.
Snow likelihood tools are intended for convenience and planning context only. They are not avalanche forecasts, road safety guarantees, or backcountry safety certifications.
Even trusted systems cannot perfectly predict:
WhichPhase is best used to reduce guesswork and improve timing, not replace official safety judgment.
Unlike live weather forecasts, many astronomical events published in the WhichPhase Observatory are individually researched before being added to the calendar.
Whenever practical, WhichPhase compares multiple authoritative references to verify dates, observing conditions, visibility, and notable characteristics before publishing astronomical events.
Different authoritative organizations occasionally publish slightly different observing notes, calculated times, or presentation styles. When that happens, additional trusted references are compared before publishing.
This research-first approach helps improve consistency, while acknowledging that astronomy, like weather, continues to evolve as new observations become available.
The following organizations form the foundation of much of the astronomical information used throughout WhichPhase.
Professional astronomy publications provide observing guidance, practical viewing advice, and additional verification of noteworthy celestial events.
Additional astronomical references are used to verify dates, compare calculations, and provide additional observing context.
Whenever practical, WhichPhase independently verifies astronomical calculations using local ephemeris software, separate from any published source.
These calculations are used to cross-check lunar phases, Moon illumination, Earth-Moon distance, eclipse timing, solstices, equinoxes, and other astronomical events.
This process occasionally uncovers discrepancies between secondary sources. No single source is assumed to be infallible.
Astronomical events are often published by multiple respected organizations.
Although these sources generally agree, they occasionally differ in calculated times, observing recommendations, visibility descriptions, or editorial presentation.
Rather than relying on a single reference, WhichPhase compares multiple trusted sources before publishing astronomical events.
The result is more than a calendar. It is a curated observatory designed to help people understand not only what is happening in the sky, but why it matters and when it is most worth experiencing.
WhichPhase combines live weather data with astronomical information that's checked against multiple sources before it's published. No single source is treated as automatically correct.
Organizations referenced throughout WhichPhase's weather, mapping, and astronomy systems, grouped by category.
Live Data Providers
Astronomy Authorities
Professional Publications
Reference Libraries
Specialized References