A finely-tuned collision to form Earth’s vital moon is tantamount to a miracle.
As earthlings enjoy the rare “supermoon” tonight (see Space.com for explanation), it’s a good time to ask where the moon came from. It is very unusual. Mercury, Mars, and Venus – the other rocky planets – have nothing like our moon. Mars has two rocks proportionally much smaller than the planet. Only Earth has a large satellite within the inner solar system, but it does more than just provide romantic nights and opportunities for photographers. It generates tides that refresh the oceans. It stabilizes the Earth’s tilt. And it possesses a remarkable “coincidence” that allows for total solar eclipses (heads up Americans: there’s one coming on August 21, 2017 from Oregon to South Carolina). As shown in The Privileged Planet, this arrangement allowed astronomers to deduce facts about the distant cosmos, such as the discovery of helium and confirmation of Einstein’s theory of relativity.
Phys.org just posted the latest iteration on moon origin theories, “New theory explains how the moon got there.” Every new theory provides tacit admission that the previous theory was wrong in some way. That’s the case here, again. Sarah Stewart of UC Davis says, “Every other body in the solar system has different chemistry” as she explains what’s wrong with the current theory of a Mars-size impactor hitting the Earth, blasting off material that coalesced into the moon:
But there are a couple of problems with the textbook theory. One is the Moon’s surprisingly Earth-like composition. Another is that if the Moon condensed from a disk of material rotating around Earth’s equator, it should be in orbit over the equator. But the Moon’s current orbit is tilted off the equator, meaning some more energy must have been put in to move it.
Moon origin theories are concocted in computers, not by watching them happen. By adjusting the angle of impact, she and her team got the moon material to wobble around the ecliptic until it settled down over “a few tens of millions of years.” She thinks this explains all the observations in one blow. “The new theory elegantly explains the Moon’s orbit and composition based on a single, giant impact at the beginning, Stewart said. No extra intervening steps are required to nudge things along.”
If history repeats itself, another model will come along to explain blind spots in this model.
Consider all the assumptions here. You have to have the right-size impactor. It has to come at the right speed. It has to impact at the right angle. It has to mix the materials just right. It has to wobble for just the right amount of time. Pile on assumption after assumption, then twiddle the knobs in the model just so, and presto! A beautiful moon, perfect for life. Stuff Happens.
For those not willing to substitute miracles of chance for miracles of design, ignore the cow jumping over the moon in the new model. Just go out and enjoy the supermoon as it rises tonight. Use it as an occasion to thank God for all He has provided us for life on a very, very, very special planet.