Take the 2-minute tour ×
Mi Yodeya is a question and answer site for those who base their lives on Jewish law and tradition and anyone interested in learning more. It's 100% free, no registration required.

What are all the halachic opinions for when to do havdalah? I'm writing a calendar and I want to provide all the options that people use.

The ones I've seen are:

  • 42 min after sunset ??
  • 72 min after sunset (Rabbeinu Tam)
  • 7.5 degrees below horizon ??
  • 8.5 degrees below horizon ??
  • 8.75 degrees below horizon ??

(Note that I calculate sunset as a zenith of 90 + 50/60 degrees.) I don't really need every single option possible, just the ones that people actually use.

http://kehillatisrael.net/hcal/zmanim.html

share|improve this question
    
According to everyone you can do havdalah from plag. –  Double AA May 15 '12 at 15:43
add comment

3 Answers

up vote 2 down vote accepted

http://www.kosherjava.com/zmanim-project/zmanim-calendar-generator/ will give you all the ones usually used. (Remember to select "Full" under Type.) Btw, Both R' Aharon Kotler and R' Joel Teitelbaum used 96 min for motzoei shabbes.

share|improve this answer
add comment

72 minutes after the sunset (Rabbeinu Tam) corresponds to the astronomical twilight, which occurs when the centre of the Sun reaches 18° bellow the horizon. At that time the smallest stars become visible to the naked eye.

share|improve this answer
    
I don't think this is accurate. Rabbeinu Tam's time is 16.1 degrees below the horizon not 18 degrees. –  Double AA Sep 17 '13 at 19:26
    
What I wrote holds true for the equator, where the Sun sets perpedicular to the horizon. However, the latitude and even the season play their parts, the magnitude of which becomes apparent from the charts one can visit: individual.utoronto.ca/kalendis/twilight/MST.pdf –  David Habart Sep 17 '13 at 22:07
1  
Your comment about 18 degrees being astronomical dusk is accurate. Your claim that Rabbeinu Tam's number equals that is questionable. –  Double AA Sep 18 '13 at 3:09
add comment

HaRav Moshe Feinstein writes in Igros Moshe that in NYC the Zeman is 50 minutes after sunset.

The Zeman most Chasidim hold (outside Eretz Yisroel) is Rabbeinu Tam which is 72 minutes after sunset.

The Brisker hold 90 minutes after sunset.

share|improve this answer
    
Did Rav Moshe say it is 50 minutes on every day of the year? –  Double AA Feb 16 '12 at 3:35
2  
@DoubleAA, Rav Moshe kept with a consistent 50. Similarly the old-school Agudas Harabonim position was a consistent 42. (Easy to follow, lichtzin+1hr). As I heard in a shiur from Rabbi Storch, angles of solar depression was too complicated a policy to tell most people pre-Internet, so often a rabbi would simply give a fixed X minutes. X will be the number of minutes that gets you the adequate solar depression on any day of the year. (Which means that yes if you convert RMF's 50 minutes to solar degrees, which Rabbi Storch describes, you'll keep 50 some days and a few less other days.) –  Shalom Feb 16 '12 at 9:13
1  
Rabbi Storch's mp3s -- part1, part2. –  Shalom Feb 16 '12 at 9:16
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.