08-06-2017, 11:57 AM | #1 |
Join Date: Nov 2008
Location: Pennsylvania
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Navigating Strange Worlds
Here on Earth, the concept of using the sun, stars, and various other objects in the sky to navigate is a common idea. On other similar planets and worlds, the same concepts and skills can still be used. The sky simply looks different on those worlds because you have a different point of reference. However, as I was doing some prep work for a campaign I will be running, it dawned on me that what I had in mind for the setting I was creating might make navigational skills and concepts, ones which I take for granted to be simple, might be more difficult.
What I had in mind was that the game's world would actually be a habitable moon which orbits a large planet. At first, I gave that little thought. I simply wanted the sky of my fantasy setting to look different, and I wanted to try something radically different than what I had used before. Upon further thought, I questioned whether or not night time navigation would be more difficult due to the proximity and/or size of the planet. I have seen pictures of what the Earth looks like from the moon, and I do not imagine any extra difficulty in that situation. But does having something larger, such as Jupiter or Saturn (or perhaps even bigger), dominating the sky upon which you're looking add any difficulty to navigating? My gut feeling is "not really," but I wanted to check my thoughts against a community which often has a better understanding of celestial mechanics and concepts than I do. |
08-06-2017, 12:05 PM | #2 |
Join Date: Nov 2004
Location: The plutonium rich regions of Washington State
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Re: Navigating Strange Worlds
A moon around a large planet will probably be tidally locked, meaning that the planet around which the moon orbits will always be in the same spot in the sky (ignoring minor wobbles from tidal libration forced by other moons around the planet). This makes navigation even easier - you can just reference your position compared to a huge big obvious planet hanging in the sky. Combined with a pole star (or group of stars near the pole, if no star is conveniently right on the pole like Polaris is for us) you get both latitude and longitude.
Obviously, this only works on one hemisphere of the moon. The hemisphere facing away from the planet doesn't let you see the planet, so you only get latitude from your sky observations, like on Earth. Luke |
08-06-2017, 12:24 PM | #3 | |
Join Date: Nov 2008
Location: Pennsylvania
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Re: Navigating Strange Worlds
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So, would that typically mean that (much like our own moon) that "night" and "day" would be measured in days instead of hours? |
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08-06-2017, 01:11 PM | #4 | |
Join Date: Dec 2007
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Re: Navigating Strange Worlds
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08-06-2017, 02:05 PM | #5 | |
Join Date: Nov 2004
Location: The plutonium rich regions of Washington State
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Re: Navigating Strange Worlds
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A couple of examples of worlds that are moons from my own setting, using physics to find their orbits: http://panoptesv.com/RPGs/Settings/V...s/Jiangluo.php http://panoptesv.com/RPGs/Settings/V...lds/Zemyna.php Luke |
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08-06-2017, 02:36 PM | #6 | |
Join Date: Nov 2004
Location: The plutonium rich regions of Washington State
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Re: Navigating Strange Worlds
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If the orbital plane of the planet-moon system is not particularly closely aligned with the plane of the ecliptic, eclipses will be much rarer. As long as you are not in eclipse, you will be able to see some sun reflecting off the planet somewhere from the moon, although it might only be a thin sliver. Luke |
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08-06-2017, 03:07 PM | #7 |
Join Date: Jun 2005
Location: Lawrence, KS
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Re: Navigating Strange Worlds
I was wondering if there's a possibility of the moon's axis of rotation pointing directly toward the planet, so the planet was its "pole star," in effect. . . ?
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Bill Stoddard I don't think we're in Oz any more. |
08-06-2017, 03:37 PM | #8 | |
Join Date: Nov 2004
Location: The plutonium rich regions of Washington State
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Re: Navigating Strange Worlds
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You would also need the moon far enough away from the planet that it wasn't tide locked. Luke |
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08-06-2017, 04:22 PM | #9 | |
Join Date: Jun 2005
Location: Lawrence, KS
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Re: Navigating Strange Worlds
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Bill Stoddard I don't think we're in Oz any more. |
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08-06-2017, 04:41 PM | #10 | |
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Join Date: Oct 2004
Location: Forest Grove, Beaverton, Oregon
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Re: Navigating Strange Worlds
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