Robert Peary’s attempts to reach the North Pole raised a curious question for Jewish scholars: How should Jewish law, which normally assumes a 24-hour day, be interpreted in the land of the midnight sun?

Writing in New Era in 1905, J.D. Eisenstein asked, “Which is the seventh day, or Sabbath? and when is Yom Kippur to be observed around the North Pole, where the day and night are of about six months’ duration?”

If one reckoned by daylight, “As to Yom Kippur, it would be obviously impossible to prolong the fast till the closing prayer of Neilah. Besides, one would have to wait for the following Yom Kippur, 354 to 384 years, figuring a year for a day, according to the Jewish calendar.”

According to Eisenstein, one rabbi advised that observing Jews should not settle in high latitudes at all, to avoid the question. The problem has not been entirely settled even today — indeed, it’s been compounded, as Jewish astronauts can now orbit the earth and may one day colonize other worlds.