Yom Teruah or Rosh Hashanah?

Yom Teruah or Rosh Hashanah? In the written Torah, the first day of the seventh month is to be commemorated as Yom Teruah (יוֹם תְּרוּעָה), sometimes translated as the "Feast of Trumpets" (Num. 29:1, Lev. 23:24). The word teruah means "shouting" or "raising a noise," and therefore this day was to be marked by making a joyful noise unto the LORD (Psalm 81:1-4). Of all the moedim (holidays or feasts), Yom Teruah is unique because 1) it's the only holiday that begins on a New Moon that is the first sighting of the moon as a sliver and 2) there is no explicit reason given in the Torah for its observance other than to "rest" and to offer sacrifice (Num. 29:1, Lev. 23:24). After the Second Temple was destroyed in 70 AD, however, the sages of the Mishnah redefined Judaism and associated Yom Teruah with the start of the Jewish civil year. Yom Teruah then became known as "Rosh Hashanah" (the head of the year).