My explanation is simple. The orbit of the cloud of rocks is well known to astronomers, as is the orbit of the earth. As these are both known quantities, it’s easy for an astronomer to calculate when we will pass through the cloud.
If it’s condensation on the underside of the firmament, please explain to me just what that is, how it causes the effect of shooting stars, and how it can be predicted so accurately by astronomers.
Oh, and none of your, isn’t it obvious answers as that just demonstrates you have no idea what you’re talking about.