Who Made the Moon?

Minds dulled, we watch the Moon eclipse the Sun, covering it like one silver dollar stacked on another, never thinking how really odd that is. Just what are the chances that the Moon would be exactly the right size and orbit to block the sun like that? The Moon could have been too large or too small or too close or too far to block the sun so perfectly. Given all the other possibilities, this arrangement is improbable, and given all the beneficial influences that the Moon has on the Earth, a superstitious mind could believe that this dollar on dollar aspect is a signal that says, “Look, I made this.”
Who Built the Moon?, a book by Christopher Knight and Alan Butler, discusses the eclipse phenomena as well as other important influences the Moon has on the Earth that make life more abundant and prosperous here.
For instance, the 23.5 degree tilt of the Earth’s axis to the sun is believed to have happened during the formation of the moon. This tilt buffers out climatic extremes: the equator is less hot than if it faced directly at the sun, the poles are less cold than if they were always perpendicular to the sun; in between, climatic conditions are moderated by seasons. In short, the tilt makes it possible for life to occur in more abundant and higher forms.
Furthermore, the moon, being large, about 1/80 of Earth’s mass, has a stabilizing effect on the tilt, preventing shifts of greater that 1.5 degrees. [Note: Because the Moon is so large, the Earth-Moon is called a binary planetary system.]
Mars, which doesn’t have a substantial moon, has a drift of its axial tilt from 15 to 35 degrees. Such changes in tilt could wipe out advanced life by making it too cold or too hot.
It’s theorized that the tide, largely caused by the Moon, has had a beneficial impact on life, stirring the primordial seas to lap the shores, encouraging life to move onto the land.
Given that the Moon has such importance to life on Earth, it’s interesting that science has struggled to explain its origin. Three imperfect theories have been suggested.
Co-accretion: The Earth and the Moon were formed at the same time from nebula dust.
Fission: The Moon was part of the Earth but spun off, like a stone from a sling, a scary concept—think of California flinging into space someday. Sinking into the ocean is suddenly benign.
Capture: The Moon came close and got sucked into orbit. Thank goodness it didn’t come too close and get sucked into the Pacific Ocean.
None of these explained the Earth-Moon very well. This issue was still unsettled at the time of the Moon landing and it was hoped that the Moon rocks would point the way to the correct theory.
They didn’t and in 1975, the scientists threw their hands up in frustration and accepted the “worlds in collision” theory. That idea suggests that something large hit the Earth obliquely, tearing off a chuck that became the Moon, and, I suppose, the impact also knocked Earth into its current, perfect for life orbit around the Sun.
This wonderful collision was a lucky circumstance for the biosphere: Moon, right size, right distance away; Earth tilt perfect, Earth orbit perfect, all just right for the biosphere to grow and prosper.
We’re just damned lucky to be here.
This, combined with the concept that a bunch of chemicals flashed together to form the first living cell, leads to the belief that life has arisen from a series of infinitesimally probable events (called outliers in statistics). You might just as well believe that we’ll find a functional space shuttle imbedded in the geological record. On the other hand, you might agree with my fictional character, Horace Haines, who says in A Far Traveler, “When multiple outliers intersect and the impossible happens, it is no accident.”
In either case, it seems that the Kepler telescope should search for other binary planetary systems. If one turns up in the habitable zone of a sun and has a moon about 1/80th of its mass, we might start asking: Who is putting these systems together—we might also thank them.