Hillel II

Hillel II (Hebrew: הלל נשיאה, Hillel the Nasi), also known simply as Hillel held the office of Nasi of the ancient Jewish Sanhedrin between 320 and 385 CE. He was the son and successor of Judah III. He was a Jewish communal and religious authority, circa 330 – 365 CE. He is sometimes confused with Hillel the Elder, as the Talmud sometimes simply uses the name "Hillel".

In two instances his name is quoted in connection with important decisions in Jewish law: in one, Jose ben Abin expounds to him a law; in the other, Hillel cites a mishnah to establish a law (Yer. Ber. ii. 5a; Yer. Ter. i. 41a).

He is traditionally regarded as the creator of the modern fixed Hebrew calendar. It first appears in a responsum of R. Hai Gaon (early eleventh century) cited by R. Abraham bar Hiyya in his Sefer Ha'ibbur, written in 1123. The topic of that responsum is the 19-year cycle for leap-year intercalations, so the most that can be inferred from that attribution is that Hillel was responsible for the adoption of that cycle for the regulation of the distribution of leap-years.

Actually there is in fact much more that can be inferred from this citation. The citation explicitly refers to the year that this event happened, 670 of the Seleucid era, which corresponds to 358/9 CE. The Molad of Tishrei for that year 4119 would be Sat 23 hours and 233 parts. Under the Gregorian calendar this would be Sat, Sept 20, 0358 17:12. Rosh Hashanah would have begun Friday evening but not before, according to lunar science, a very bright Old Moon will rise Friday morning at 4:11 AM, an hour and 34 minutes before sunrise. The significance of this can be found in the Talmud Rosh Hashanah 25a.

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