Incidence angles of meteoroids

Question

I've been reading the book Planetary Geology. In chapter 7, section 7.6, the author states that

The angle of incidence at which asteroids or comets encounter the surface of
a planetary body follows a Gaussian probability distribution with vertical and
horizontal collisions being extremely unlikely and the highest probability existing
for 45°

Why is this the case? Why doesn't the angle of incidence for meteoroids follow a uniform law? Isn't there just as much chance for an asteroid or a comet to arrive from any direction?

Ioannes · Accepted Answer

Horizontal atmospheric entries are unlikely because the object would have to almost miss the Earth and brush against it rather than impact it (and probably would disintegrate in the atmosphere if it's a small one, due to the long flight through it in such case).
Vertical entries are unlikely for the opposite reason: the object would have to fly at precisely 90 degrees relative to the Earth, meaning the Earth is in the very center of the object's orbital path.
But if an asteroid or comet comes at another angle its path may be changed by the Earth's gravity towards about 45 degrees. This is an approximation, it is about 40-50 degrees, but 45 degrees is the most likely one out of specific angles.

Incidence angles of meteoroids

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