Lunar Eclipse Contacts and Durations
Learn how lunar eclipse penumbral, umbral, and totality contact times are reconstructed around peak and how each phase duration is interpreted.
Lunar eclipse calculation methods
A lunar eclipse calculation searches for the Moon passing through Earth's penumbral and umbral shadows. The finder brackets a selected UTC instant with global eclipse peaks, classifies each event, and reconstructs its available contact times from modeled phase semi-durations.
This method hub separates event timing from coverage measures. Contacts and durations describe when shadow phases begin and end. Obscuration describes covered disc area at peak, while umbral magnitude is a different diameter-based catalogue quantity and is not emitted by the current calculator.
How this calculation is divided
The engine enumerates lunar eclipses around the input and returns a strictly previous and strictly next peak. Events are penumbral, partial, or total. The nearest result is selected by elapsed time, without treating a larger or total eclipse as automatically nearer.
Penumbral, umbral, and totality contacts are derived by subtracting and adding the available semi-duration around peak. Phases that do not occur are represented as absent. The results are global geometry; no observer coordinates are accepted and no local visibility promise is made.
Two technical guides
Eclipse Obscuration vs Magnitude
Compare lunar eclipse umbral obscuration with umbral magnitude, understand area versus diameter measures, and see which value the finder reports.
Scope boundaries
- This section does not generate event-date, year, country, city, “Blood Moon,” or viewing-guide pages.
- The calculator does not decide whether an eclipse is above the horizon for a local observer.
- Obscuration is reported only where the engine supplies it; umbral magnitude is explained but not invented.
Use the working calculation
Open the Lunar Eclipse Finder to evaluate another exact instant with the production logic described here. For the shared time model, accuracy policy, and supported era, return to the methodology overview. The implementation and independent references are listed on the sources page.