Is it true that Rosh HaShanah is also called Yom HaKeseh, meaning “The Day of the Hiding” or “the Hidden Day.” I noticed that it’s called this way because of Tehillim 81. Is it true it’s also called this way because it’s concealed as to when it starts and that it can only start when the moon begins to reflect again?

I find this interesting because somewhat our own wrongdoings and sins are consealed, but during this period from Rosh HaShanah till Yom Kippur we’re quite reflective.

  • There are a handful of references to Rosh Hashana as "Keiseh" in the Selichot for Erev Rosh Hashana
    – Double AA
    Sep 9, 2018 at 14:38
  • We refer to it by that name in kidsush,...bakeseh yom chageinu
    – sam
    Sep 9, 2018 at 16:42

1 Answer 1


The Talmud (Rosh Hashana 8a, 34a) states:

תקעו בחדש שופר בכסה ליום חגנו איזהו חג שהחדש מתכסה בו הוי אומר זה ר"ה

Which is the Festival day on which the moon is covered, i.e., hidden? You must say that this is Rosh HaShana, which is the only Festival that occurs at the beginning of a month, when the moon cannot be seen. (Sefaria)

It refers to Rosh Hashana because it occurs before the moon begins to reflect.

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