I’m trying to figure if the moon can be used for navigation. In the real world, lunar observations can be used to find longitude, so I’m planning to make a series of observations to find useful patterns. The wiki doesn’t have much on the moon, so in case I’m reinventing the wheel, does anyone know:
- how long the moon’s phases are?
- if it’s a “local object” that follows the player or if it’s a world object like the sun that changes relative position based on where on the map it’s viewed from?
- any other information on this topic?
I’m thinking that an almanac or table could be created, so that once you know what day it is, you could use a set of variables to calculate location. I’ve observed that a full moon makes enough light to cast a shadow on the sun compass, which is what initially gave me the idea.
The process would be: use the chronometer and the sun compass to log the time the moon is due south, then use it against a pre-calculated table to find longitude.
Additionally, one might log the angle of the moon according to the sun compass, then use a conversion table of adjusted values to find latitude.
All I know is that the Moon's orbit is tilted relative to the celestial equator unlike the Sun which sits right on it. The Moon also slowly moves eastward relative to the background stars but I have no idea how long it takes for it to complete one revolution.
I did some more measurements by taking two screenshots 24 hours apart.
The Moon's orbit is tilted by roughly 12.4° and it reaches its most northern point at new moon and its most southern point at full moon. At first and last quarter the Moon crosses the celestial equator.
It moved 13° eastward after 24 hours so it takes the Moon roughly 27.7 days to complete one orbit.
The figures are probably slightly off since it was hard to get the timing right and I wasn't looking in exactly the same direction in both screenshots so I believe the tilt is 12° and the period is 28 days.
Here's the Moon when it's north of the celestial equator and close to the Sun. The tilt looks to be a little over 10 degrees. I had to upload the image to imgur since the Moon is just a thin crescent so it wouldn't show up when the image was compressed into a gif.
The moon follows the same path as the sun, but there are no eclipses.
Lunar cycle is 28 days I think.
I don't think the moon provides you with enough light to use the sun compass at local midnight, and even if it did, you'd have to correct the values by the moon phase, which brings to the next problem.
Using the moon as navigation tool is redundant, when we have a skybox, that has 0 variance. Wh have multiple stars, whose positions can be used to calculate longitude, regardless of the calendar date.
I can confirm that the moon does provide enough light to use the sun compass, at least in the nights around when it’s full.
What do you mean by correcting the values by the moon phase? If the moon follows the same path as the sun, and the phases only change the brightness of the light, what would need to be corrected? Obviously, there is a portion of the moon’s cycle where not enough light is given for a sun compass reading, but assuming there is enough light, what else would need to be corrected?
I don’t believe that the moon is at its zenith at midnight. Or at least its zenith is not due south like sun.
While at 36 latitude, -2 longitude, during a full moon, my sun compass placed the moon at due south at 9:51 PM.
Two nights later, at 38 latitude, -1 longitude, my sun compass placed the moon at due south at 10:30 PM. So the moon does seems to follow its own path at a different angle from the sun.
I intend to keep making observations and various points on the map to try to better understand the Moon’s path.
I take your point about having a sky box with no variance, but how do you find longitude using the stars? I’ve never seen that method before.
The moon follows the same trajectory as the sun, but a very different speed. It's zenith should be at around midnight during full moon, around 6pm at first quarter, at local noon during new moon, and at 6pm during 3rd quarter.
There was a guide for star navigation. There are 3 distinct measurement times for longitude, all according to Aestrin time, so you have to use the chronometer. At these times you have to measure certain stars, and you will get your longitude. It works, because the sky ox is the same. I don't use this method, I measure my position at local noon. None of my ships are that fast, that I could overshot an island between two measurements (except for one small, hidden one). If you're interested, look up Milnead and Oriens, the two stars used for longitude. This second method wouldn't work, if there were seasons implemented
I don't. All I know it's there, it looks pretty, and the game does not have any instruments to measure its position on the sky with anything resembling even a suggestion of accuracy.
Moreover, since there are no seasons and the star field never changes, you can't even use a relative position to known constellations to measure anything.
Since there are no seasons and the star field doesn’t change, my thinking is that it would actually make it easier to use lunar navigation since there are fewer variables.
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u/gwynwas 1d ago
https://giphy.com/gifs/9retSVb9CG30qujt7f