Welcome to the World Factory (Kintsugi Space World Building Thread)

Welcome to the world factory! This is where we make worlds, with a specific focus on different planets, and space in general have fun, and enjoy your stay on Magrathea!

 

By the way, could this also work for a fantasy setting?
Like, asking people about climate, air pressure, etc in a fantasy world?

Would be interesting to see more worldtypes in fantasy, they all either seem to be Flat World or Earth With Different Continents.

 

@QuotableRaven You might want to change the tag from World Building to Worldbuilding. Other worldbuilding threads don't have the space in their tag.

ETA: What's Magrathea?

 

Its a Hitichhikers Guide to the Galaxy reference. warning, potential spoilers for the series if you ever plan to read/watch it.

 

oh, okay!

 

Does anybody want to hear about weird orbits? (Disclaimer: i am not good at math, it'll all be from google etc.)

 

yes please.

 

[camps out in here] hello yes my fav thing is that thing floating around about a donut shaped planet

 

You mean this?

 

All I know about it is that political maps would get much more inconvenient to make because you'd need a shitton more colors to avoid getting two same-color countries touching.

 

nah, just two colors per border

 

Turns out it's 4 colors on a sphere and 7 on a torus. I guess that one article I read that talked about over a dozen for a torus was bullshitting or using outdated information.

 

Okay!

So, starting with a typical orbit. In a typical orbit, something is falling towards something else, but is far enough from it and moving fast enough that it basically misses and goes around the thing instead.

Most orbits are elliptical, with the orbiting thing swinging close to its primary (thing it orbits) and speeding up, then slowing down again in the wider portion of its orbit.

When it comes to things orbiting Earth, there's very low orbits like the International Space Station, which is actually technically still in atmosphere, and has to use occasional 'station-keeping burns' to maintain position and counteract the very slight drag it gets.
Then there's higher orbits, in which the main forces that can disturb its orbit are the gravity of the sun/moon, the extremely slight differences in gravity over different parts of the Earth, and solar radiation pressure.

There's also very high orbits-geostationary orbits, geosynchronous orbits, and High Earth Orbit. A geosynchronous orbit is an orbit where the satellite is moving in step with the rotation of the Earth. This doesn't necessarily mean it stays over the exact same place in the sky-if it's not in line with the equator, it'll move a bit. This is used deliberately to increase coverage, as satellites that trace a figure-8 orbit can provide communications coverage to areas like northern Russia, where a geostationary satellite can't reach because there's planet in the way. Usually, geosynchronous but non-geostationary satellites use the Molniya orbit, which traces a figure-eight in the sky, with a narrow, small loop that the satellite spends most of its time in, and a wide, huge loop that the satellite spends little time in. Three Molniya-orbit satellites, with the same orbit but 120 degrees/eight hours away from each other, are used to cover two areas each. On the ascending loop of their orbit, the northern satellites cover northern Europe and Asia. On the descending loop, they have better visibility to North America and cover there.

There are also orbits where the objects orbit a common center of mass that is outside of either object. For example, Jupiter does not technically orbit the Sun, but rather a common center of mass that is slightly outside the Sun. (Yeah.) Pluto and Charon both orbit a common center of mass that is closer to Pluto than Charon.

And then there's horseshoe orbits and orbits involving donuts.
Horseshoe orbits are orbits that resemble the shape of a horseshoe-the outline of a horseshoe. These orbits involve a large object in between the two 'prongs' of the horseshoe. They always orbit the same way relative to their primary, but alternate between a slower, farther out orbit and a faster, closer in orbit, switching when they come close to the large object due to the large object's gravitational effects. From the PoV of the large object, the horseshoe orbiting thing would appear to rush up, slow down, and speed away-but from the PoV of its primary it merely changes distance a bit.

Things orbiting a donut are weirder. If they exactly orbit the equator, they might as well be orbiting a sphere, but if their orbit is tilted it becomes a rosette (kinda like the Homestuck spirograph). If it orbits closer to the poles, then it goes up and down in the sky as well as rosetting. It looks really weird.
You could stick a moon in the exact center, but then if anything hits it it'll move. However, if the moon is bobbing up and down through the hole, it's stable! Same if it goes in a curved, somewhat rectangular region of the inside sky. Or it could have an orbit that, when drawn out fully, looks like a vase-like the bobbing up and down orbit, except it moves in a longitudinal circle too. Or its orbit could be a complex 'figure-8' orbit, forming another torus/donut shape when fully drawn out. This link explains it better, as it has diagrams.

 

Although, that link does assume that the world will start with an amount of water proportional to Earth's. It might luck out and get less-water spreads out, and Earth's oceans are so deep, that without the Moon to cause increased tectonic activity, we might have had only occasional shield volcanoes above the waterline.
Also, large amounts of ocean are essentially biological deserts. There's hardly any life there-there's a huge depth range where there's no sunlight and no sea-floor nutrients.

 

Tiny correction: satellites in Molniya orbits aren't geosynchronous, their orbital period is half a day. From the ground's point of view, their orbit looks like this, with most of the time being spent in the two smaller loops:

 

Oh, whoops.

 

Does anybody here want to infodump about planetary composition, uses of the stuff in Venus's atmosphere, or asteroid mining?

What I know on that topic is "venus apparently has valuable stuff in its air", "bigger planets are usually less dense" and "gravity in an iron-cored world increases as you approach the core because the iron outpulls all the rock above your head", and that last one is learnt from Witch of the Iron Core.