Picture a double planetary system, in which two bodies of approximately 0,5 and 0,7 times the mass of Earth orbit a common barycenter. Both bodies are also tidally locked to one another. Neither of them has got a considerably thick atmosphere if they've got one at all.

The fact they orbit and face each other has got me thinking... Would the sides facing each other suffer more meteoric impacts? Would the sides opposed to each other do? Does this even matter at all?

  • $\begingroup$ are they 1:1 tidally locked? and do they have the same masses. $\endgroup$
    – John
    Aug 24, 2021 at 12:55

1 Answer 1


The greatest number of impacts would be on the leading edge of each planet, in their mutual orbit.
Simply because they present a very similar gravitational environment to the outer surfaces, but have an additional relative speed as they sweep through their orbit.

The difference will be tiny.

The sides facing their companion planet will have the least, but most violent, impacts.
Because the other planet provides a bit of a physical shield, the number of impacts will be somewhat less.
And because the inward-facing sides are deeper into the joint gravitational well of the double system, any meteors that pass through there will have gained more velocity from falling further into, (and then past) the barycenter of the system.

Again, the difference will be tiny, unless the two planets are very, very, very close to each other.
(for example, the Moon shields the Earth from less than 1/160000 of incoming meteors. But its added mass makes the Earth-moon system 1/80th more attractive to wandering meteors.)


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