Calendar According to Sighting

Explore a continuous experimental sighting chronology alongside standard Hebrew dates and local Moon observations.

Follow an experimental month sequence from a chosen calendar anchor and compare sighting-calendar dates with the standard Hebrew calendar. The observer panel shows the Moon against a local horizon with altitude, direction and illumination.

Review the month decisions and their consequences over time. A simulated crescent or a chosen month boundary is not a recorded witness observation. Atmospheric conditions, horizon geometry and the selected astronomical model affect the comparison.

Jewish Cosmology is an interactive research and educational web application connecting Hebrew dates, traditional Jewish calendar calculations and halachic concepts of time with the observable motions of the Sun, Moon and planets, astronomical seasons and eclipses.

JavaScript is required for the interactive explorers and calculations. The descriptions and navigation remain available without JavaScript.