Unfortunately, I don't see a convincing theory among the three presented in the reading. Let me explain. Two problems cast doubt on the fission theory. When put to the test, models show that a force capable of breaking off a chunk of the Earth the size of the Moon would've destroyed the entire planet instead of sinking into the ocean. Also, an inspection of lunar rocks collected during the Apollo missions convinces us that the Moon was once hotter than the Earth. So you see, fission would've been pretty much impossible. And another issue-the rocks themselves have a different chemical composition from that of the Earth's crust.

Now let's look at co-accretion. Remember that this hypothesis assumes that the Moon and the Earth came into existence at the same time, but here's the problem with that-gravitational forces would probably have fused them together, or they would share more characteristics than they do. I mean, how do we explain the relatively small iron core of the Moon at only 25 percent compared to the much larger iron core of the Earth at 50 percent?

Which brings us to the impact hypothesis. Let's say for purposes of argument that the planet that crashed into Earth-the one about as big as Mars-let's say that happened, and the debris from both planets orbited the Earth and eventually created the Moon. But if there was debris, then why didn't it form a group of moons as would be predicted, instead of just one moon? And why didn't the moon rocks show evidence of the kind of biochemical processes we would expect, the kind that would accompany extreme evaporation from a massive collision?

So, from my point of view, and quite a few of my colleagues would agree with me, well, we just need to keep looking, because none of our current theories are adequate.