“The Big Splat, or How Or Moon Came to Be” by Dana Mackenzie. Published by John Wiley & Sons, Inc. in 2003, it weighs in at 232 pages all-in. No errors noted.
Having looked at the origins of the Moon from a Christian creationist perspective, I figured it would be a good idea to take a look at what the scientific community thought about Lunar origins. So I turned to the Selenology (or Moon science) section of the Lunar Library and The Big Splat seemed to be a perfect choice.
In the Introduction, the author looks at Genesis Revisited, quickly summarizing the history of thought regarding Lunar origins, and the noting how the application of the tools of science changed the way we approach the idea of the source of our companion Moon. On our first visit to the neighborhood of the Moon, Apollo 8’s circumlunar swing on December 24th, 1968, the crew read from the text of Genesis, imparting a call to the spiritual nature of humanity’s endeavors, wherever they may occur.
In the first chapter, we look at how our companion Moon has waned from an integral part of timekeeping and spirituality in human culture to a marginalized object supplanted by the advent of science. Technological lighting methods diminished the Moon’s role as a nighttime guide. A better understanding of the Earth’s place in the Solar system led to the adoption of a Solar calendar, though there are still many cultures that abide by the Moon’s guidance. We learn of notable figures in history who helped divine her secrets, her characteristics and her cycles.
Chapter two continues the recounting of history, and we learn of Anaxagoras, Pythagoras, Aristarchus and Aristotle,as well as lesser known Lunar-associated figures such as Plutarch, Lamprias, and Pharnaces.
Chapter three moves the story to the early 17th Century, as science and reason were blossoming throughout Europe. Two gentlemen are the focus of the discourse – Kepler and Galileo, who did more to popularize space science amongst a broader audience than any other of their time. We end with Riccioli, whose basic nomenclature for Lunar features is the methodology we use to this day.
Later in the same century, science and mathematics took a big leap when Newton burst upon the scene, and in the next chapter we examine how his principles led to a leap in understanding the seemingly clockwork nature of our Solar system. By the next century the questions were moving away from how it works to where it came from. Folks like Buffon and Kant were postulating ideas on how the grand forces of physics could have led the Universe to today, but it was Laplace who became known for the ‘nebular hypothesis’, whereby the planets and their moons formed from a nebula surrounding and providing the feedstock for the nascent Sun. Also noted is the role of navigation in uncovering the fact that the Moon’s orbit is not as clockwork as one would assume it should be.
It was in the 19th Century that the next major hypothesis for the origin of the Moon was promulgated, by George Darwin, son of the more commonly known Charles. George worked on the science of tides, specifically tidal bulges, which occur when one massive body is in the vicinity of another. Everyone knows the Moon pulls on the water of the oceans to create the tides (in conjunction with the Sun), but it also pulls on the ground. He worked through the mathematics and realized that months were getting slightly longer, which begged the question of what happens when you run the time arrow backwards? This implies an intersection at some point in the past of the Earth and Moon, which implies that the Moon came from the Earth. What would be the physics that would make that happen, where the Moon would fission off from the Earth and escape to orbit. It was a tough slog to try to make the mathematics work, and the idea of a Daughter Moon never really found favor.
Another compelling theory is visited in the next chapter, that of the Captive Moon. This idea holds that the Moon formed elsewhere in the Solar system, went on an errant journey (perhaps nudged by Jupiter), and ended up captured in orbit by the Earth. In this chapter we learn of Thomas Jefferson Jackson See, who championed this explanation for the Moon’s origin. T.J.J. See may not have been the most pleasant of individuals to deal with, but his theory had a certain elegance of orbital mechanics to it, if only the numbers could be made to work, something that scores of scientists pursued over the next century. We’re introduced to the concept of the Roche limit, the distant from a large mass at which a smaller mass begins to feel gravitational differences between the point nearest the large mass and the point farthest from the large mass sufficiently large that it begins to tear the smaller mass apart. This is what is believed to have torn apart Comet Shoemaker-Levy-9 prior to its plunge into Jupiter. Ultimately, the mathematics of capture couldn’t be reconciled with reality, and it remained a plausible, but not proven theory.
Next up is the concept of a Sister Moon, where the Earth and Moon co-accreted near each other in space. We learn more about the work of Roche, as well as others that worked out the physics of accretion in early stellar systems including Safronov, who worked out many of the details of how accretion works.
So by the dawn of the space age there was still a lot unknown about our closest neighbor in space, let alone destinations beyond. It was widely held that the craters of the Moon were largely of volcanic origin, and that vast seas of ash and dust would swallow any spacecraft that presumed to pose upon the surface. It was during this popular wisdom that Baldwin published a book that threw a monkey-wrench into the works, alleging that the craters were actually the result of collisions. Being an outsider to the Ivory Tower of academic knowledge, his theories were controversial, but he had solid evidence on his side, as we had learned much about cratering from two worldwide wars. One scientist inspired by this book was Shoemaker, another Urey, both of whom would have a significant impact on Lunar science. On the eve of Apollo, the ideas were flying fast and furious as more and more bright people took the time to cogitate on the topic of our Moon.
Chapter nine covers the Apollo missions, and provides an overview of some of the bigger questions that seemed to be answered, like “How old is the Moon?” and “What is the Moon made of?” As the scientists worked over the samples, a general consensus began to arise as to the general steps the Moon took once formed to arrive at its present state. Left unanswered was the question of what caused the Moon to form.
In the next chapter the clues start to come together. A paper had been written in 1946 that called into question whether the Moon may have had some kind of glancing blow with the Earth. 1950 saw the publication of Velikovsky’s “Worlds in Collision”. Apollo proved definitively that most of the craters on the Moon were of impact origin, and as we looked around the Solar system we could see evidence of impact everywhere. Four scientists, Hartmann, Davis, Cameron & Ward, started homing in on the theory that reconciles so much of the evidence on hand that for many it is “the” way that the Moon formed.
It wasn’t until the mid-80s that all of the pieces started clicking into place, and the next chapter explores the Kona Consensus that developed out of a conference on selenogony, or the origin of the Moon. As paper after paper was presented, scientists realized that a cogent and rational explanation for the Moon’s origin was coming together. A report card prepared about the different theories shows why it was so compelling. The mathematics of the event had been well worked out in computer modeling. The chemistry was favorable, and readers get an introduction into the chemistry and mechanics of rock dating techniques.
The last chapter introduces us to Theia, the alleged impactor and mythical mother of Selene. Since no one was around to observe it (yet, time travel may not be beyond the realm of possibility, although I believe it is), there are many unknowns. One obvious question is ‘Where is the hole?’, to which George Darwin would probably answer ‘The Pacific’, but in reality the impact totally rearranged the Earth, incorporating both original bodies (proto-Earth and Theia) into both subsequent bodies (Earth and Moon). The author lays out the timeline of events, from impact to about 3.2 billion years (gigayears, or Gy) ago, when the Moon finally became somewhat quiescent, and then the present.
In the appendix, the question of ‘Did We Really Go to the Moon?’ is addressed. I am so over this particular topic, but like a parasite it seems it will evermore be rediscovered by new generations and need refuting time and time again, which is a complete waste of resources. The Lunar Library has a number of the Moon-hoax titles, which are bunk, and management would rather not waste acquisition budget on any more of them. The author presents several compelling examples, including the fact that it’s possible to actually contact the scientists with questions. Not mentioned is the fact that we found five (5) new minerals on the Moon which had not been seen previously (though Tranquillityite was later found in South Africa).
Rounding out the book are a nice glossary, some references, acknowledgements and an index.
What’s nice about this book is that it is written for a general audience. The author is completely frank about the fact that the science sometimes went over his head, and he is careful to frame things as ‘scientists explain-this is how it’s done’. It makes a nice counterpoint to the Moon origin books previously reviewed, as the explanations are laid out at the end of a chain of logical steps. Objective evidence is offered in support of assertions, evidence that exists in physics irrespective of the presence of humans. The flow of the writing is easygoing and engaging, making for a pleasurable read. The author prefers the term Big Splat to the more commonly known Big Whack, and he has good reasons why.
This one gets a Full Moon rating.