Explore Jewish time through astronomy.
Tekufah: Traditional Seasons and Astronomical Seasons
Compare traditional tekufot with the calculated equinoxes and solstices used in the seasons and calendar tools.
The term
Tekufah can refer to a seasonal turning point. Jewish calendar discussions include traditional arithmetic models, notably the cycles attributed to Shmuel and Rav Adda. Their mean periods must be distinguished from individual astronomical events.
Astronomical meaning
Equinoxes and solstices describe seasonal positions of the Sun relative to the equator and ecliptic. A calculated event is an instant, whose civil date and clock display depend on timezone. A repeating mean interval does not reproduce every actual seasonal interval.
Use in Jewish Cosmology
The Seasons explorer compares traditional tekufot with calculated solar events. The experimental calendar also compares true Tekufas Nissan with dates in its adjusted year. This comparison exposes a model relationship; it does not by itself establish a binding rule for intercalation.
Explore related concepts
About Jewish Cosmology
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.
Models, terminology and limitationsHalachic times are unverified, have no rabbinic approval, and must not be relied upon for practical halachic decisions unless and until an appropriate authority approves them.