*NOTICE* Although my article lacks the flair in it's opening paragraph as compared to other articles of the same title on this website, please bear in mind that this is the only existing article at the time of publication that presents what is currently accepted as scientific fact worldwide. *
There have been countless theories stretched over the endless millennia of human existence that have attempted to deal with what the moon was and where in God's name (or any other deity's name) the moon came from. Three theories stand out among them as the most widely-accepted hypotheses. These are the Fission Theory, the Capture Theory, and the Collision Theory. Below we'll take a look at these one by one.
== Fission Theory ==
The Fission Theory posits that our earth once spun much faster than it does today. So fast, in fact, that at one point it managed to throw a chunk of itself into orbit, thus forming the moon. This theory works on the basis that as an object rotates at increasing speeds, it begins to flatten out and bulge in the center, much the same concept as if I were to spin a $1.99 bouncy ball from a Wal-Mart bin at a fast rate. The faster the ball spins, the more it squishes into a disk shape or flying saucer shape.
When put on a large scale and given the fact that the earth is rather elastic in structure, it's easy to see how a chunk the size of the moon may be "thrown" into orbit. Think of a pizza. Pizzas are made into flat circles of crust from balls of dough by being spun. As the pizza baker throws the dough up into the air, he gives it a spin which "pulls" on the pizza in every direction causing it to flatten out. If the pizza is spun too quickly however, a chunk of the dough is liable to fly off and hit the kitchen wall. The exact same is true for a planet. If the planet is able to spin so fast that it starts to flatten out, one of the weakest portions of the planet might be completely ejected from the planet's crust and rocket out into space.
While it is physically possible for this to occur, it's simply improbable. The earth would have to spin so immensely fast for this to happen that, once it was actually able to throw a portion of itself into orbit, that piece would just keep on going. It would be moving far too fast for the earth's gravity to be able to hold onto it. Also, the composition of the moon is too far removed from the composition of the earth for it to have once been part of our planet.
== Capture Theory ==
This theory is far simpler. The capture theory basically states that the moon and the earth are two completely separate objects that crossed paths at some point billions of years ago. This would mean that the moon would have to be an asteroid or other similar body that passed so close to earth that Earth's gravity pulled it in. The problem with this theory is that the moon is far too large for the earth to capture. The moon would just keep on its merry wayor crash fantastically down to earth causing all life to end instantly.
== Collision Theory ==
This is by far the most accepted explanation of the birth of our moon. This one has been worked out to the minutest of details. The collision theory states that at some point, about 4.3 billion years ago, a planet the size of Mars had an orbit around the Sun that was almost identical to Earth's orbit, except it went the opposite direction. For several million years, Earth and this smaller planet (which is called "Orpheus" by many scientists) passed by each other without a problem. Over time, they began growing closer and closer to each other, until Orpheus eventually collided with Earth. Orpheus hit Earth at an angle that spun Earth around on itself, just allowing Orpheus to make a pass by Earth and coalesce into something of a sphere before being dragged back in to Earth in the opposite direction to hit the other side of Earth, spinning Earth even faster. By this point, Earth and Orpheus were nearly indistinguishable from each other, as they had both been reduced to enormous balls of molten iron, rock and vapor. The angle with which Orpheus collided with Earth was precisely the right angle to be able to slow Orpheus down enough for most of its mass to be able to stick around earth, without floating away.
Once the collision was more or less over, large amounts of Orpheus had become part of Earth, and pieces of both Earth and Orpheus had been ejected into space giving Earth rings. Yes, Earth used to have rings. For Earth, these rings were incredibly fleeting, though. Within 100 years, all of the chunks and particles encircling Earth had lumped together into what we now know as our moon.
This theory also explains several other phenomena, such as the Cambrian explosion when life seemed to pop into existence on Earth. It allows for life to have existed on proto-Earth, or Earth Mark I, before the moon was formed. This would explain why life appeared so quickly after the impact that formed our moonlife had already existed here! It also explains why the moon is similar to earth, yet dissimilar at the same time.
With no legitimate counter-proposals made and no variable not covered, it seems that the Collision Theory is here to stay.