When does Shabbat start on the moon? NASA has decided that the moon needs its own timekeeping system, so how will the moon’s now-nonexistent Jewish residents pray, light Shabbat candles, and observe the festivals?

The question is interesting because the Jewish calendar is beholden to the sun, and the sun appears and disappears at unusual times when you’re not on Earth. An astronaut on the International Space Station will see the sun rise and set 16 times every day, while a moon resident will go two weeks before seeing either one.

Will an observant astronaut on the ISS need to pray three times every 90 minutes, keeping Shabbat once every 10 hours? Perhaps the lunar Shabbat lasts for an entire month. Tell a prospective astronaut that he or she must pray 48 times a day and, likely, no one will listen, or will elect not to become an astronaut.

However maintaining some links to Earth times holds the door open for some form of interstellar Judaism; after all, diaspora Jews use a liturgy that is deferential to Israel’s agricultural cycles, although most of them have never been there.

Space Judaism may be a weird slurry of adapted ideas, forged by the brave human beings preparing our faith for its next journey.

Adapted from an essay in The Forward

by David Zvi Kalman