A weekly feature of Torah Tidbits to help clarify practical and conceptual aspects of the Jewish Calendar, thereby better fulfilling the mitzva of HaChodesh HaZeh Lachem... Slight correction. More like a fine tuning. Last opportunity for Kiddush L'vana this month (in Israel) is THU Oct. 28, 8:00pm. Correct...except for someone who SAW the lunar eclipse in the wee hours of Thursday morning. AND knows its significance vis- a-vis K.L. It's a long story. Let's go for it. K.L. is said from the time of the month that the moon is MEI'IR LAARETZ, shines onto Earth (3 or 7 days after the molad - dispute - forget this part for now) until it is full (meaning, as long as it is waxing, i.e. growing - after full moon, the moon starts to wane, diminish). The halachic tradition is to use the "average" molad for the purpose of beginning and end of K.L. time (and for the announcement during Rosh Chodesh Benching) and not to use the actual (a.k.a. astronomical) molad and nigud (no moon & full moon). On average, the moon takes 29 days, 12 hours, 44 minutes and 1 cheilek to go through its cycle of phases. And the calculations we use for Rosh Chodesh Benching, for Kiddush L'vana, and for determining Rosh HaShana in our fixed calendar are based on this average. What it amounts to is starting with a given "molad of Creation" and adding 29d 12h 44m 1p (which is the same as 29d 12h 793p is one doesn't use minutes but rather divides an hour into 1080 parts - same thing) for every month that passes. Here's the wrinkle. The time it really
takes the moon to go through its cycle varies from month to month. This is
due to Kepler's second law of planetary motion (i.e. G-d's law of planetary
motion, discovered by Kepler), the masses of the Earth and Moon, and a few
other factors. Regardless of why it happens, it happens. Not so simple for the real, actual, astronomical molad. The actual molad of Tishrei was TUE 16:29 (Israel Standard Time). Cheshvan's was THU 04:48. That means a lunation of 29d 12h 19m. Close to average, but less. And with Kislev's new moon on a FRI 16:27, it will take the Moon only 29d 11h 39m to go through its phases. The difference between the actual time it takes the Moon to go through its cycle and 29d 12h 44m 1p can be several hours more or less. More to the point, the time of the molad (not just the duration from one until the next), varies between the average figure and the actual. At the moment, we are more interested in
the NIGUD, which is the midpoint between one molad and the next. Whatever
was said about MOLAD applies to NIGUD. The average NIGUD (deadline for K.L.)
is gotten by adding 14d 18h 22m (half of 29d 12h 44m) to the molad.
Cheshvan's molad (remember?) was THU 2h even. Adding 14 d 18h 22m brings us
to THU (Oct. 28) 20h 22m, which is just a little after 8:00pm on Thursday.
That was the time we listed as the last op for K.L. Some poskim hold that there is an exception to the above. And that brings us - after many words - to our point. A lunar eclipse occurs only at full moon. When one watches the eclipse AND knows that when the eclipse is over (even before) that full moon just took place, then he may NOT say K.L. after that time. Follow this. Knowledge that full moon actually took place (which a person can know easily every month) does not in and of itself preclude saying K.L. after the actual full moon time, but before the halachic deadline, of course. But EXPERIENCING the full moon does prevent one from saying K.L. afterwards, even though it is before the official halachic deadline. Miss the eclipse? See it and not know what it means? Your K.L. deadline is 8:00pm THU. See and understand? KL only until eclipse begins. [The
Parshat Vayeira Homepage]
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