The Torah is considered to be the blueprint of the entire creation. It is therefore not surprising that the great sages took an interest in the movement of the heavens, both from an astronomical and an astrological point of view.

The Talmudic sage Mar Shmuel (Nehardea, Babylon, c. 165 – 257 C.E.) was well versed in halacha (Jewish religious law), civil law (Persian) and medicine, but was especially known for his love of astronomy. He is quoted as saying: “Although I am as familiar with the courses of the stars as with the streets of Nehardea, I can not explain the nature or the movements of the comets” (Talmud Berachot 58b).

All that Mar Shmuel knew of the stars and the planets he discerned with his naked eye, for this was centuries before the first telescope was created (c. 1608 C.E.). In Talmud Shabbat 75a, Mar Shmuel quotes Rabbi Yochanan as saying: “From where do we know that it is a person’s duty to calculate the cycles of the seasons and the constellations? Because it says, ‘Since this is your wisdom and understanding in the eyes of the nations’” (Deuteronomy 4:6). And so he applied himself to study how the celestial bodies affected the calendar. For instance, by observing the revolutions of the moon he was able to predict the beginning of the new moon in Palestine, even though he was in the diaspora. Practically, this could have been used to remove the necessity of celebrating double festival days outside of Israel* (Rosh Hashana 20b). Because of his affinity for applying astronomy to set the calendar, Mar Shmuel was given the affectionate appellation Yarchinai (related to yareach, which means moon).

*For an explanation of double festival days, please click here.