cellio: (mars)
[personal profile] cellio
I was recently asked about this, and I don't know what the current thinking is.

The question of when an astronaut observes Shabbat (while in space) is well-understood. [1] But what happens when we colonize other planets and your hometown is on Mars? Do you count six Mars-days and observe the seventh as Shabbat? How long is a month (and how do you decide which moon)? Is it still desirable to stay in sync with Earthly seasons, or will that go out the window? If you follow the sun as locally experienced, what happens when that causes hardship? (Does the lunar colony observe one ~29-day Shabbat every seven months?) There must be commentary on this by now from sources other than Wandering Stars, but I don't know what the popular opinion is.

[1] I know of three opinions for the astronaut in space: follow your hometown, follow the city from which you launched (your port of departure, like for ships), or follow Jerusalem. All of these involve a ~25-hour Shabbat every seven days, like on Earth, even though your orbit might cause you to see a 90-minute day. But the astronaut is, by definition, just visiting.

(no subject)

Date: 2007-05-03 06:20 am (UTC)
geekosaur: spiral galaxy (galaxy)
From: [personal profile] geekosaur
Actually, the phase of the moon has nothing to do with the moon's day vs. its orbital period; it's solely related to its angle relative to the Sun as seen from the Earth, so depends only on how long it takes the moon to orbit the Earth.

As seen from Mars, phases would behave rather differently, because they would be restricted by the Sun-Earth-Mars angles as well as the Sun-Moon-Earth angles. Also, the moon would usually be invisible: either behind the Earth, or in front of it and drowned out except when Earth and Mars are fairly close to each other (but then it would be a dark spot against a mostly dark spot, instead of a light spot against a very light spot).

(no subject)

Date: 2007-05-03 04:27 pm (UTC)
From: [identity profile] zevabe.livejournal.com
I think I was insufficiently clear. If I stood on Mars, what would the phases of the moons of Mars look like? How long would a full cycle (new moon to new moon) take?

(no subject)

Date: 2007-05-03 05:47 pm (UTC)
geekosaur: spiral galaxy (galaxy)
From: [personal profile] geekosaur
Wikipedia knows all....

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