A Question of Jewish Law

May 5, 2017

35. Between Day and Night (Part 1)

Filed under: Festivals,Jewish Law,Prayers and Blessings — chaimweiner @ 8:20 am

Question: What is the earliest time for counting the Omer?

Answer: There is a commandment to count the days between the 2nd day of Passover and Shavuot. To fulfil the commandment, each day is counted on the appropriate day. Therefore, the earliest time for counting the Omer is the beginning of the day.

When does a day start? The Babylonian Talmud says that the day starts in the evening, based on the verse: “And there was evening, and there was morning, day one”. [Gen 1:5] Even so, determining when evening falls and the next day starts is not easy.

Day and night are astronomical phenomena. As the earth turns on its axis it appears to us that the sun moves across the sky. As the sun dips beneath the horizon it becomes dark. At some point between the light and darkness lies the border between day and night.

If we were sitting on a boat on still waters at sea level, near the equator, with clear skies, in a remote area with no light pollution – we would be able to discern several stages in the process of day becoming night. First, we would see the sun start to move down towards the horizon, its rays gradually weakening because of its angle in the sky. We would then see the moment that the ball of the sun first touches the horizon followed several minutes later by the moment that the last sliver disappears beneath the horizon. The sky would still be light, but as the sun continues to sink beneath the horizon it gradually darkens until the stars appear.

To further complicate matters many external factors can change our perception. If we are at a higher altitude the sun would appear to go down later. If we are in a valley surrounded by mountains, the sun would appear to have gone down earlier. The length of time it takes for the sun to go beneath the horizon changes according to our position on the globe. And if there are clouds or air pollution or artificial light in the background, we may not see the stars until much later, if at all.

This gradual transition from day to night provides several potential moments that could count as the beginning of the next day; the sun starting to go down, it reaching the horizon, it disappearing beneath the horizon, the appearance of the first stars. In fact, the Rabbis were unable to determine an exact moment for the beginning of the day. Instead, the period of time during the transition from day to night is called twilight [in Hebrew – Bein HaShmashot  בין השמשות – literally, “between the suns”]. Twilight is of doubtful status. The Sages taught: Twilight is a period of uncertainty, [both] day and night, uncertain it is completely day,  uncertain completely night. [Therefore] impose the stringencies of both days upon it. [BT Shabbat 34b]

What is the exact definition of twilight? The Talmud states:

And what is twilight? From when the sun sets, as long as the eastern face is reddened. If the lower has lost its colour, and the upper has not yet lost its colour, twilight. If the upper has lost its colour and equals the lower, it is night; the statement of Rabbi Yehuda. Rabbi Neḥemya says:  The time for a person to walk half a mil after the sun sets. Rabbi Yossi says: Twilight is like the blink of an eye: This enters and that leaves, and it is impossible to calculate it. [BT Shabbat 34b]

Following this, the evening can be divided it into 3 distinct periods. Up to sunset (defined as when the sun disappears beneath the horizon), it is day. After the stars appear (from a halachic point of view this means 3 medium-sized stars) it is night. Twilight falls during the time between sunset and the appearance of the stars. Exactly when it falls depends on the opinions of the various Rabbis.

Therefore, the ideal time to count the Omer is after 3 stars appear in the sky. Then you can be sure that you counted on the right day. If you count between sunset and nightfall you may have filled your obligation, and you can continue counting.

But is it possible to count any earlier? This is a serious question for those living in northern localities. As the counting of the Omer falls near the summer solstice, sunset can be very late – sometimes near midnight. For this reason, Rabbis have tried to stretch the time that counts as being night as much as possible. I will look at some of the ways this can be done in my next post.


Rabbi Chaim Weiner

Iyar 5777











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