In a Rocheworld scenario where two planets are tidally locked and share an atmosphere, but where both the planets are so small that their gravity is very little (as low as one of the dwarf planets in our solar system, such as Ceres, for example), is it possible for creatures that can fly to go back and forth between the planets via the shared atmosphere? Handwave the existence of a breathable, dense Earth like atmosphere of course.

Could a humanoid character fly from one of the planets to the other through that area of shared atmosphere if he/she had wings (again, handwave), or one of those flying squirrel suits with something like a Buck Rogers rocket jet pack?

The way I understand it is that: They’d need enough lift to get off the ground (this place has low gravity and they’d have their wings or jet pack), and they’d have to be able to push further than the Lagrange points because if not they'd be stuck in orbit (but again, wings/jetpack, right?).

So is it possible, or am I missing something else?

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    $\begingroup$ If the binary pair of planets are outside the la roche limit, then the first concern that comes to mind is endurance. It would take a lot of energy and time to fly between the two worlds. $\endgroup$ – Arvex Jan 24 '18 at 1:27
  • $\begingroup$ @Arvex, I'm imagining a livable environment in which a creature could stop, take a break, snack on another creature or some floating water and plant life (still working on that stuff). A person would bring along supplies and his/her jetpack could be nuclear powered. But yes, endurance and time are concerns. $\endgroup$ – Len Jan 24 '18 at 1:34
  • $\begingroup$ Uh... have I done something to make this question UN-answerable? lol $\endgroup$ – Len Jan 24 '18 at 16:05
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    $\begingroup$ "I'm imagining a livable environment in which [...]" It is essentially de rigueur to read Niven's The Integral Trees and Smoke Ring before proceeding. There's lots of room for further story telling in similar environments, but not knowing those books would be like writing about vampires without having read Dracula. $\endgroup$ – dmckee --- ex-moderator kitten Jan 24 '18 at 23:42
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    $\begingroup$ @Len There's still plenty of space to explore in the concept. :) (All puns intended). You can either read the existing books for inspiration or you can avoid reading them so you come at it fresh (but risk accidental overlap). Each approach is equally valid :) Ideas are cheap, it's how you implement the idea that matters. $\endgroup$ – Tim B Jan 25 '18 at 21:56

In a low gravity situation, with enough handwavium as it would take to put two planets, with atmospheres, that close together, without them colliding, there would be enough residual handwavium for flight-capable humanoids to traverse the gap. In fact, I believe that there would be a strong case for a species with leg-strength capable of jumping the gap, as the gravity at the point where the atmospheres are tangent, would be even lower due to the overlapping gravitational fields.

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  • $\begingroup$ So It would be at worst like sky diving? A survivable jump from one planet to the other? $\endgroup$ – Len Feb 2 '18 at 15:44
  • $\begingroup$ Anything with leg strength capable of jumping past the gravitational transition would probably be capable of catching itself on landing, and anything capable of flying that high(depending on how thin the atmosphere gets, but there would probably be an "air bridge") would just have to roll over. $\endgroup$ – Brian Lami Feb 10 '18 at 1:27

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