In one of my universes, I have a binary planetary system comprised of two planets, one slightly smaller than the other, that touch each other, like let's say a basketball touching a football. Both planets are inhabited by life

This world ignores the laws of physics and many things rely on magic. On both planet a civilization develops.

Assuming both civilizations have the same level of technology and one day they meet for the first time in history. What can possibly happen if both civilization meet each other? (For better or for worse)

Edit: Removed the deity/heaven question, as me trying to follow Gryphon's advice. Simplified the question into one.

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    $\begingroup$ Hello Victorbrine Cassini, and welcome to Worldbuilding! Unfortunately, this question seems very broad, which we discourage on this site. Perhaps you could edit to focus on one specific point? Please visit our help center and take the tour to learn more about the site. Have a nice day! $\endgroup$
    – Gryphon
    May 30, 2018 at 15:16
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    $\begingroup$ Welcome to worldbuilding. You posted two unrelated question about your world. Please limit to 1 question per post. Also, try to avoid opinion based question, for which it's not possible to objectively measure the quality of an answer (yours are both OB) $\endgroup$
    – L.Dutch
    May 30, 2018 at 15:21
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    $\begingroup$ I'd love to put my two cents in here but Gryphon is quite right, this question is far too broad to give you a good answer, you need to focus it on a single specific issue you wish to explore. $\endgroup$
    – Ash
    May 30, 2018 at 15:22
  • $\begingroup$ On a related side note, what you are describing is called a contact binary. There is a continuum from what is basically a single planet spinning fast enough that it is peanut shaped, probably with two separate iron cores, to a more stretched peanut only being connected via a thin land bridge, to two deformed planets with an air gap in between, and finally to what is truly two separate twin planets, with separate atmospheres, just orbiting each other. $\endgroup$
    – AndyD273
    May 30, 2018 at 15:53
  • $\begingroup$ Just simply, if they have the same nature of humans, one would probably try to dominate the other and war would break out. $\endgroup$
    – Etanos24
    May 30, 2018 at 15:53

1 Answer 1


My take on the Touching Worlds concept:

This world is, in many respects, a terrifying world to live on!

Ignoring the Laws of Physics we know in the primary world is a good idea, because I don't think it would end up well. Even so, there would have to be some kinds of similar Laws in this other universe. For example:

  • In order to keep people from floating off either planet, both will have to have gravity of some kind. Perhaps the kind that weakens a bit near where the two planets touch. You know, to keep them from smashing into each other.

  • I would imagine that the twin planets share a single atmosphere.

  • Your vision of the touching worlds may differ, but in mine, they rotate independently, then they must rotate in opposite directions. Like meshing gears.

On to the terror!

I think the farther towards the poles you go, people on either world would see very little during the day. Possibly a dark smudge low on the horizon. The air itself will scatter light and (if oxygen) the sky will be blue. We'll see other reasons for the smudge below. Also, clouds and thickness of the atmosphere will interfere with any kind of viewing.

At night, early in their existence, they will see a darkish disk that eats and spits out stars! As the planets revolve, the motion will bring people gazing heavenward towards the darkened disk of the sister planet. This will move into the visible field of stars and as the other planet "rises" and "sets", it will cover and uncover stars behind it. They will also be able to see the discharges of lightning during storms on the other planet. I suspect that, if the timing is right, before sunrise, the people on Planet A might be able took low into the eastern sky and see the first radiant burst of sunrise breaking upon Planet B. Spectacular!

As time goes on and cities evolve and thaumology and technology advance, they may see the lights of cities at night and perhaps powerful discharges of magic. If the people of one world are sufficiently advanced over the other, the primitives might indeed wonder of the other planet is the home of strange and wonderful gods!

Closer towards the middle latitudes, the above effects are magnified. Also, as the dual planet itself revolves over the course of the day, there will be times when much of the planet is in day-dark: when the twin is between the planet and its star. Due to the rotational motions of each individual planet and the joint rotation of the twin planet system, there will be, quite possibly, predictable schedules of Day-dark and Day-light. And interesting almanac folks must have in those latitudes!

As we approach the equator itself, a whole new experience awaits the intrepid wanderer. In that direction, beyond the lands of the most marginalised nomads, I would suspect that there will be quite literally a dead zone. Darkness, except perhaps for a pale light reflected into the Gap Between the Worlds, reigns here. And the terrible lightning generated by the howling storms.

Worse, since the planets are touching and rotating, this whole zone is a realm of incomprehensibly loud sound, probably enough to deafen: the constant roar and groan of two worlds perpetually grinding past one another must be astounding indeed! The constant pulverisation of mighty boulders must kick up a constant upwelling of dust and stone and the hurricane force winds that must blow through and along the Gap must be simply irresistible! Nothing's going through that land! I might also expect two zones of lateral vortex storms, one septentrional and one austral, on either side of the Gap where the airs of the two atmospheres collide. When one planet rolls over an ocean, it must kick up a terrifying gale and perhaps also send tsunamis in all directions.

Since we've dispensed with Physics somewhat, I think the only way for two civilisations to meet is to fly! A powerful airship must be built that can fly high enough to get above the raging Vortex Storm. As the two gravity wells touch and intermingle above the raging clouds below, the airship captain must set a delicate, curving course that will bring her ship over the storm and into the calmer atmosphere of the other planet beyond. From there, she can set a course as she usually would and arrive at her destination on the other planet.

NOTE!! The grinding storms of the Gap will not allow easy travel between hemispheres of either planet! And the Gap itself will be far too wide for people to contemplate travel. Ground travel will be impossible: I suspect even if you set out on your fastest steed as soon as the great Vortex Storms subside for the day, you'll not get far enough across the Gap before you feel the tremors and see the pummeling breakers and incessant lightnings of the other world heading in your direction!

Maybe in a few centuries, we might hear tell a story of some crazed Northerner travelling through the lands of the Southern nomads with some kind of mechanical mole turtle in tow. At the last marches of their land, they watch with a certain sorrow as the madman's armoured machine whirs into life and burrows into the tormented earth of the Gap...

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    $\begingroup$ No. These two worlds are "tidally locked" to each other. Which means that the smaller planet or larger one doesn't "roll" on the other. Instead if you wear to observe at the other planet, it would stay "static". However this concept of a world "rolling" on the other is quite interesting, but that's not what I first envisioned. Also as I said the laws of physics are ignored. If you stood on one of the planet and went to the point they touch, you would still have your feet on the ground and you can "world jump" on the other and walk normally as well. $\endgroup$ May 30, 2018 at 16:47
  • $\begingroup$ Hm. Like I said, your vision of the concept may differ! Tidally locked is interesting too. Most of my conjectures will hold, I think. Their atmosphere will still be too thick and too blue to see much of the other, except close to the equator. Close to there, you'ld be able to look "up" for quite a distance and see the other planet clearly. I still wouldn't be surprised if the weather around the Touchpoint weren't horrid. $\endgroup$
    – elemtilas
    May 30, 2018 at 16:59

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