Last year I flew from Tel Aviv to Los Angeles. The flight leaves at night (1am) and, in the winter, lands when it is still night (630am). However during the flight, over Greenland, one sees the sun then it disappears somewhere over Canada and it is night again until the "real sunrise" on the West Coast.

In this case, when is the right time for shaharit?

Normally one prays at the time of one's current location. But in this case the sun over Greenland is not the "real morning" for that day. Or maybe there are two mornings?

This is important because if the time for prayer is over Greenland and one doesn't pray there - then one cannot eat during the next 8-9 hours until one prays on the West Coast.

And if the time for prayer is over the West Coast then one cannot pray over Greenland.

I could not find answers for this situation. Has anyone encountered this situation and asked a rav? Or do you have sources that would explicity address this?

PS. See here for the return question on not praying arvit if the sun never sets

  • I believe there may be a Siach Nachum that may address this. – Loewian Jan 11 '16 at 5:31
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    Possible dupe: judaism.stackexchange.com/q/55644/2091 – Lee Jan 11 '16 at 10:59
  • @Lee thanks, it is a great site which I had seen once. Key issue is that the route a plane uses can differ very much between season and day depending on the winds. A more Southern route wouldn't have the issue described above. So we need rules to decide based on seeing the sun/night not just based on the plans. The mystery remains for now :-> – mbloch Jan 11 '16 at 11:51
  • When the sun goes back down, it goes down in the east not the west, right? It's not setting. This is not that different from the sun rising and then me running fast westward a bit till it goes back down. Still an interesting question, but no need for the convoluted case. – Double AA Aug 7 '19 at 23:16

From http://ravbaruch.com/AskTheRabbi.asp?QID=92#_ftn2:

Reportedly, Rav S. Z. Auerbach z’’l and Rav Moshe Feinstein z’’l ruled that if one experiences two sunrises on the same day of the week, one is obligated in only one tefilloh. The time cycle for tefilloh is once a day, regardless of how many nightfall’s and sunrises there are on that day. Since they hold that tefilloh is day-sensitive and not sunrise-sunset–sensitive, it follows that someone who davens and then crosses the dateline westward (leading into the following day) has to daven again even though he did not experience a sunset or second sunrise. If it is the day that requires the tefilloh, then since he is now in a new day, he must fulfill that day’s tefilloh obligation.

Rav Elyashiv is reported to hold the opposite opinion and to consider tefilloh to be sunrise-sunset–sensitive. In that case, two sunrises in one day obligate the person in two tefillos, whereas crossing the dateline in a westward direction (effectively stepping into the next day without nightfall) does not require a new tefilloh. These two views regarding tefilloh are expounded upon in Rav Betzalel Stern’s Betzel Hachochmo, and Rav Yechezkel Roth’s Emek Hateshuva.

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    This has big implications for someone in low earth orbit. – Adám Jan 11 '16 at 13:18
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    @NBZ There is a joke about the Israeli astronaut who staggered out of the capsule exhausted saying "shacharis, mincha, ma'ariv - every ninety minutes" (:-) – sabbahillel Jan 11 '16 at 16:22
  • @NBZ I believe I've also seen a view cited (mis-cited?) that the zmanim follow the ground above which you're flying, i.e. if the sun isn't visible there, its visibilty to you is irrelevant. – Loewian Jan 11 '16 at 19:07
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    @Loewian : I accepted your answer with thanks (not that there was a lot of choice :->) I didn't want to write it initially to avoid framing answers, but I saw a number of people on the plane pray over Greenland, while a number of others waited. Now I know who they were holding from. I personally waited. Thinking back I think someone in doubt should probably pray twice with the stipulation that the second tfila is ndava if not required. But thanks to you we know both options are legitimate (eilu v'eilu ...) – mbloch Jan 12 '16 at 16:51
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    Since they hold that tefilloh is day-sensitive and not sunrise-sunset–sensitive, it follows that someone who davens and then crosses the dateline westward (leading into the following day) has to daven again... Relevant: judaism.stackexchange.com/q/322. – Fred Jan 12 '16 at 23:44

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