Posted: Mon May 14, 2018 5:04 pm Post subject: Moonrise/Moonset
I confess that a lot of discussion involving Oerth's solar system and the calendar goes over my head.
From what I can tell about the moons, their cycles are so regular that the same nights each year have full moons, half moons, or new moons, etc. That also suggests the times of moonrise and moonset are consistent from year to year.
I want to create an adventure that takes place on the night of Growfest 4th (spring equinox). I want the adventure to begin with one of the moons rising, and conclude when that same moon sets.
Does anyone have any information or learned guesswork on when moonrise and moonset would be that night?
I was amusing myself writing a VBA almanac for Greyhawk, at one point, and moon rise and moon set times were extremely complicated if I remember correctly. A lot depends upon latitude. I ran out of energy to pursue this in the detail desired, and did not consult Greyspace which might have proven helpful. Short version, I made a series of very crude guides for storytelling, but not particularly helpful for high detail.
During a full moon, the sun rises exactly 6 hours before midnight, and sets 6 hours after midnight. When the moon is waning, moonrise will occur less than 6 hours before midnight and moonset will occur more than 6 hours later, proportional to how far from a full moon the date is. The reverse occurs during a waxing moon, when it rises more than 6 hourse before midnight each night, and sets less than six hours after midnight. In all cases, I had the moons in the sky for 12 hours, shifting the rise and set times.
This rule could use some revision, and does not account for latitude. Given time, I may revisit the approach for Luna... Celene might be more troublesome, even suspending Newtonian Mechanics. I recall that calculating e (elongation) had me giving up as it brought back bad memories of geometry and I was not attempting to earn a masters in astronomy at the time. That, and without a heliocentric model, it becomes nightmarish to contemplate the sun's position.
In your second paragraph, where you say "sun" you mean "moon" right?
Why would Celene suspend Newtonian mechanics? Wouldn't it just have a longer orbit?
I just checked Weather Forecaster for Greyhawk's World, and saw that Luna will be at 1/4 on Growfest 4 and Celene will be full, so I'll use Celene's rise and set as the bookends of the adventure.
The latitude will be 27 degrees N (southwest Sterich) and sunrise at 5:34am and sunset 5:49pm. If your link holds true for Celene, then I think we can set moonrise and moonset around those times (or split the difference and say 5:41am & pm).
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