Seasons

Compare Shmuel and Rav Adda tekufah calculations with astronomical equinoxes and solstices for a selected Hebrew year.

Compare traditional seasonal reckonings of Shmuel and Rav Adda with calculated solar-longitude crossings: the equinoxes and solstices.

Traditional clocks are anchored to Jerusalem standard time; civil clocks use the selected location’s timezone. Astronomical seasonal crossings are geocentric events, not local sunrise or sunset.

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.