Quran 2:187:
The following is taken from “The Holy Quran in Today’s English” by Yahiya Emerick under the commentary of the above verse (note 165):
(You may) eat and drink until the white thread of dawn appears distinct from its black thread. Then fast until the night approaches again,
Commentary (Note 165):
People who live in the extreme north or south of the globe, where there are prolonged periods of dark and light, must observe the fast according to a regular timetable that reflects the rhythms of normal life elsewhere on the globe. Once a man asked the Prophet what people would do if they lived in a place where there was shortened day or night, and he responded, “Then go by normal days.” i.e., fix a schedule regardless of the movement of the sun. This principle can be applied to prayer during space travel, as well.
References:
Emerick, Yahiya. The Meaning of the Holy Qur’an in Today’s English (p. 827). Unknown. Kindle Edition.