The Yom Tov of Rosh HaShanah is considered to be a Yoma Arichta, one single long day. This means that the two days of Rosh HaShanah are considered to be one 48-hour day. The obvious question is why? Why is Rosh HaShanah regarded as “one long day,” as opposed to other Yamim Tovim which are celebrated for two days outside of Israel? This question yields several answers.
The Aseret Yemei Teshuvah, the Ten Days of Repentance between Rosh HaShanah and Yom Kippur, correspond to the Ten Commandments. The first two commandments were said by Hashem Himself, making these two commandments extra holy. Therefore, the first two days of these ten days, the days of Rosh HaShanah, are like the first two commandments, making these two days extra-holy. Because of this intense holiness it is considered one long day.
The Gemara (Rosh HaShanah 16b) states that when the Shofar is sounded on Rosh HaShanah, the Satan becomes confused and is unable to harm or complain about the Jews. If Rosh HaShanah were to fall on Shabbat, there would be no Shofar blowing and the Satan would still be in power. However, Rosh HaShanah is considered “one long day,” so the final judgment of Rosh HaShanah would not happen until the second day, when we would be allowed to blow the Shofar and would be able to banish the Satan.
The Baal HaTanya presents a Gematriya (the letters of a Hebreof the special power of a 48-hour Rosh HaShanah. He cites the Pasuk (Tehilim 39:4) which states “Cham Libi BeKirbi.” “My heart grew hot within me.” The Gematriya of the word Cham, meaning hot, is 48. This 48 alludes to the 48 hours of Rosh HaShanah which should be spent with the heart becoming “hot” through our Tefilot.
This Rosh Hashanah, may we all have a Ketivah VaChatimah Tovah and merit the coming of Mashiach speedily in our days.