I know that the title sounds like a sequel to a TV show (Lost in space). But based on a statement in this article :

The Rabbis therefore rule that a person should continue to follow the time from the place from which he departed. Based on this, it is possible that different people in a space station or on the moon who came from different places will be observing different times.

If a Jew was born in space (station), he has never "departed" from Earth. What times does he follow, or does he follow his Mom's minhag? Let's assume that Dad is still on Earth and Mom travelled to the space station while she was pregnant (If any of these factors would matter in answering the question?)

  • (What about if Mom & Dad departed from different locations?) My guess would be that baby is a mother-extension until they can recalibrate on some planet. Sep 24, 2015 at 8:53

1 Answer 1


This is a fun question. Thanks for asking @DanF. The issue of time in regard to Shabbat and Yom Tov is not an issue of minhag. It is a matter of Halacha. In regard to your question, while in transit it would be like traveling on a plane. You would follow by the time of your point of departure once you left earth orbit.

Once you landed at your new destination you would follow the sunrise and sunset of the place you are in, like for example the moon or Mars. This follows a general principle mentioned in Shulchan Aruch HaRav, Orach Chaim, Hilchot Birchot HaShachar, 46:1 and 5. Everything follows the order of the world in that particular location.

A space station would appear to leave open the possibility that individuals could be holding by different times if they came at different times and their point of departure was from different time zones like with an international space station. One Jew coming from Russia, one from the United States and one from Israel. But even then, the worst case would be a gap of only 24 hours.

In the case of Mom and Dad, it is most likely they normally reside with one another. Even if temporarily one departed from a different time zone, they would follow from where they reside.

Baby is considered in this question like the portable property of the parents. They would follow Mom and Dad.

  • Can you source "Once you landed at your new destination you would follow the sunrise and sunset of the place you are in, like for example the moon or Mars."? Similarly to locations within the polar circles, this may work for counting days, how about special days during the year? Also, PELs may be problematic.
    – Adám
    Dec 13, 2015 at 13:32
  • @NBZ per your request a source is added. Regarding locations like polar circles where single days, meaning actual sunrise and sunset, could be months long, the general idea is to follow the more normal time of the place you last left. There are comments by some poskim that places like this are not good locations for permanent residence. I don't understand what you mean by "PEL". Dec 13, 2015 at 17:18

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