Q&A relating to changes in time zones
Shabbos is calculated based on 24 hours and not based on daylight or night. One thus counts six days of 24 hours and sanctifies the seventh day as Shabbos. However there requires further analysis regarding the times of prayer.
May one who owns a business in a later time zone have the business open at the conclusion of Shabbos of his time zone?
- Example: One lives in Israel and owns a business in the U.S.A.
No. the business may only open after Shabbos in its time zone has concluded.
In the above scenario may the business remain open on Erev Shabbos until Shabbos begins in its time zone, or must it close at the time the owner accepts Shabbos?
Some Poskim rule that the business must close by the time the owner accepts Shabbos in his earlier time zone. Others however rule that the business may remain open until Shabbos begins in its own time zone.
May one call or send a fax to an area of a later time zone if Shabbos has not yet ended there?
May one send an e-mail to a person of a later time zone if Shabbos has not yet ended there?
May one travel after Shabbos to a country that is in a later time zone?
- Example: May one travel from Australia to California or from Israel to the U.S.A. immediately after Shabbos ends.
It is forbidden to initially travel to an area with a later time zone if he will be arriving into the time zone when it is still Shabbos there. If one went ahead and traveled there he must keep the remaining hours of Shabbos in that country.
 This can occur by areas near the North and South pole. It is most common in cities in Northern Finland, Norway; Russia; Canada; and Alaska. A common tourist city in which this occurs is the city of Longyyearbyen, Norway. During the summer months the sun never sets, and one thus does not experience night. During the winter months the sun never rises, and one thus never experiences day during those months.
 Shaareiy Teshuvah 344 in name of Mur Uketzia; Shaareiy Halacha Uminhag 1/134
 Piskeiy Teshuvos 344/2
 Eretz Tzevi 44; Minchas Yitzchak 7/34; Betzeil Hachachma 3/125
 Chelkas Yaakov ???; Shraga Hameir 2/65
 Beir Moshe 6 Kuntrus Electricity 49; Chelkas Yaakov 3/106; Betzeil Hachachma 3/125
 See Piskeiy Teshuvos 344/2
 Piskeiy Teshuvos 344/2 in name of Betzeil Hachochmah 83
Such as traveling from New Zealand to Hawaii in which if one leaves right after Shabbos he will arrive on Shabbos in Hawaii.