It is believed that in prehistoric times,
an ice comet collided with the
earth with so much force at a
spot near the Yucatan Peninsula,
that a chunk was dislodged and hurled
into orbit. This collected and compacted
becoming the earth`s moon.

I think you will find that the Earth had two moons, and the one in a
decaying orbit hit the Earth - creating the (now burried) crater, as well as
leavin us with a somewhat thinner crust. The bit of green cheeze out there,
over our heads, is as old as the "inner Earth", but like the Earth, it is
steadily growing as more space debris arrives.

If a comet had struck the Earth, then just the sheer momentum would have
destroyed it, if it had been big enough to hurl something out of the Earths
gravity. Even the Manson comet was not that big, and look at the size of
that crater ;-)

But back to space dust - Fred Hoyle (a well-know scientist from Yorkshire,
England) pointed out that we all have noses with the holes underneath so
that our air-intake is sheltered from the debris and diseases that are
falling from space. Fred also invented the term "Big Bang", although he
meant it sarcastically, in true Yorkshire fashion. (Eeeeeeee bah gum! The's
nowt as odd as fowk!)