Gliese 581-G (Just for fun)

[Nexis]

HI.

I was reading this thread and had a thought. Depending, of course, on the planet having a small or large elliptical orbit. This may cause sun watchers to see the sun "Beat like a heart" in a year. This may have more theological implications than navigational.

The other idea comes from Eratosthenes. The scholar who measured the circumference of the world by measuring the path of the sun by studying the shadow of a stick. If you place a stick directly under the sun at 90 degrees from the ground it would cast no shadow. Moving away from that stick and place another, it would cast a shadow directly away from the center under the sun. Do this in a circle and farther away you can have a very accurate navigation instrument and mapping. Carrying a "Sun Compass" will tell you how far away you are from the "Sun-ward" center of the world and the direction of the shadow will always point in that direction. That will create a compass if you standardize the height of the stick you can measure the distance away you are from "Sun-ward" by measuring the length of the shadow. Say If you want to reach the city of Randar you must travel North- East of sun-ward for seven shadow lengths. North south east and west generally being directions away from the Sun Center of the world.

[Podcreature]

I actually was thinking of having an elliptical orbit for the sake of temperature flux basically seasons, but they'd be on a 2 month cycle, lol. May be worth it, but the "pulsing" sun would be really neat.

And that is the best example of navigation on a planet like this I've heard yet... or at least for a very specific navigation tool that incorporates the planet's tide-locked status. The length of the shadow would definitely be the key there. Would have to maek sure it's level though. Maybe you could wear it on your wrist like a watch, and it could be a little globe, or flattish orb, water filled, so the plate inside stays level, and in the center of the plate is a little needle or something. This wouldn't have to be very big at all. With the direction of the sun and the length of the shadow, you could know exactly where you are at any time! With this and a map you'd be set.

UPDATE: Well I did a little mooore research and apparently the orbit of our planet is eccentric, but slight flux in distance from our sun has very little to do with our seasons. I kindof already knew it had something to do with Axial tilt but didn't know which played more influence. (Wasn't as interested in this stuff when I was in school, lol) So... I'm thinking this planet will have some kind of axial tilt, because seasons will be very helpful for life, but it will cause the sun to change position notably. So to navigate with such a thing as a sun-dial, you'd need to know the season, too I guess. Currents and dynamic weather can actually increase the size of the green band considerably... I wonder if an eccentric or elliptical orbit really would cause noticeable change in sun's appearance.

In conclusion, this planet will probably have an equator, a minuscule elliptical orbit (since it was probably two planets orbiting each-other and one was lost, disrupting a perfect circle slightly) and most likely an axial tilt, since scientists think the collision that produced our moon was the cause of Earth's. There are magnetic poles but I wonder if the sun will still be useful in mapping too if it moved in the sky a bit. Might need a map for each of the 55 days in a year.

And here's the finished chart, I'm basically done with this for now... until I decide to update the planet's topology, and create a real map with political and climate information. (The moon isn't that small, it's not orthographic view, it's how big it actually looks from the planet.)