17th-Century Extraterrestrials

At last spring’s Philadelphia Science Festival I talked about early 17th-century thoughts about extraterrestrial life. Here is a draft of that talk.

17th-Century Lunar Men

The news recently has been filled with stories about Kepler 186f. In case you missed it, Kepler 186f is an earth-sized planet orbiting near the outer limits of the habitable zone of a dull little star about 500 light years away. Its discovery has prompted speculation and celebration that astronomers have finally found earth’s twin, or maybe earth’s cousin, or perhaps earth 2.0.[1] Twitter exploded—to the extent that it Twitter ever “explodes” about scientific discoveries—with optimism about this untrammeled world as if it’s some postlapsarian paradise, or at least in the minds of many Twitters a pre-capitalist paradise.[2]

While news articles and tweets typically overstate the similarities between Kepler 186f and the earth, even astronomers get caught up in the excitement, describing their great progress finding habitable planets and their hopes of finding planets that show some form of alien life.

This is not the first time that people, astronomers and otherwise, have looked to the heavens in the hopes of finding habitable planets. Nor is it the first time people have imagined traveling to those planets and finding a paradise inhabited by beautiful human-like creatures. If we turn back the hands of time 300 years, we can watch as astronomers, natural philosophers, and authors wondered about the inhabitants of our nearest neighbor, the moon.

In the early 17th-century there was a flurry of scientific and popular speculation about habitable planets and extraterrestrial life. Philosophers, astronomers, theologians, lapsed Catholics and Protestants all chimed in. Certainly part of the motivation for contemplating other worlds was prompted by growing familiarity with the new astronomy. Following Copernicus and his heliocentric system, people wondered about the size of the universe. The comfortable, finite universe was expanding and seemed likely to lose its limits entirely. If the universe was infinite, how many of those little dots, those stars, were really suns like ours? And how many of those suns were home to planets like ours? And how many of those planets supported life, perhaps like us? These were real questions with real consequences for people in the late–16th and early–17th centuries.

Giordano Bruno is probably the most (in)famous person to think about the size of the universe and the number of other habitable planets. But in many ways his wild speculations were vague flights of fancy grounded in nothing but his own imagination. Much more interesting, I think, are the more restrained arguments of people like Johannes Kepler, the German astronomer/astrologer who is best remembered for his three laws of planetary motion, or John Wilkins, an English clergyman and member of the Royal Society, or Francis Godwin, an Anglican Bishop. They turned not to distant stars in their early-modern search for extraterrestrial life, but to the planet they knew best, the moon.

Join me as I glance first at Kepler’s dystopian lunar world and then at Godwin’s lunar utopia.


Kepler first speculated about the moon, its atmosphere, and its inhabitants in 1610, shortly after receiving a copy of Galileo’s Starry Messenger, in which Galileo reported his first telescopic observations of the moon and stars, and his discovery of the four moons of Jupiter. Kepler was giddy with excitement as he read Galileo’s descriptions of the moons of Jupiter. Imagine, Kepler wrote, the Jovians who look up from the surface of Jupiter and see not one but four moons, and imagine how much more light those moons must provide at night for Jovians as they wander about. For Kepler, the moons of Jupiter had to exist for a reason. And, just as our moon existed for us, the moons of Jupiter must exist for inhabitants of that planet. He wrote:

The conclusion is quite clear. Our moon exists for us on the earth, not the other globes. Those four little moons exist for Jupiter, not for us. Each planet in turn, together with its occupants, is served by its own satellites. From this line of reasoning we deduce with the highest degree of probability that Jupiter is inhabited.

Jupiter is fine and all, but Kepler became really excited when he read Galileo’s description of the surface of the moon.

The moon, with its mountains and valleys, turned out to be a lot like the earth. The large dark and light areas must, it seemed reasonable, be land masses and seas, just as on earth. Kepler agreed with Galileo that the dark areas were oceans while the light areas were continents. Kepler was sure an atmosphere of air and clouds encased the moon — he claimed that his teacher had even observed rainstorms on the moon. If the moon was like the earth with mountains, valleys, an atmosphere, and water, it must also support life. Indeed, when Kepler looked closely at the drawings of the moon in Galileo’s book, he thought he detected evidence of intelligent inhabitants. Caves. He saw evidence that the moon’s massive inhabitants, for Kepler was certain they would be much larger than humans, had dug out enormous caves to live in. Beyond evidence of their handiwork and his brief comment about their size, Kepler refrained from describing the lunar inhabitants. He was sure, however, that advances such as the telescope would soon reveal them to us.

Kepler never stopped thinking that the moon was inhabited. Over 30 year he collected his ideas together in a book published just after he died, his Dream. Here Kepler mused more concretely about the moon’s inhabitants and the conditions on the moon. He considered the length of the day and the night—each 14 time longer than our day or night. How and when lunar people slept. He also worried about how the lunar creatures survived the unbearably hot lunar day. And how they kept warm during the long, freezing lunar night. While their caves provided some shelter from the sun, he thought he had good evidence for thick layer of clouds that covered the moon and offered some relief from the sun during the lunar day. To help them survive the lunar night, Kepler pointed out that the light reflected from the earth would provide some warmth.

When Kepler turned to life on the moon, he realized it would have to be very different from life on earth—the lunar climate was too harsh to support creatures just like humans. He imagined a sort of antediluvian nightmare world populated by giant winged, reptilian and amphibian creatures that lived short, harsh, nomadic lives.

But why was Kepler so interested in who or what lived on the moon?

Kepler worried about our place in the universe:

Well, then someone may say, if there are globes in the heaven similar to our earth, do we vie with them over who occupies a better portion of the universe? For if their globes are nobler, we are not the noblest of rational creatures. Then how can all things be for man’s sake? How can we be the masters of God’s handiwork?

At the core of Kepler’s Dream are profound questions that animated thinkers in the early 17th century:

  • If other planets are inhabited, do humans live on them?
  • If humans live on those planets, did God create them and did each world have its own Adam and Eve, and Original Sin?
  • Had Christ died for their sins?
  • And if so, did Christ die once, on earth, for all the universe’s inhabitants, or was he some sort of planet-hopping savior, dying an infinite number of deaths on an infinite number of planets?

In short, were we alone and unique in the universe or were we just part of some cosmic hoi polloi?


Astronomers like Kepler weren’t the only people to ponder such questions. Popular writers too worried about these issues in numerous books and pamphlets in early 17th century. Francis Godwin, an Anglican bishop, wrote one of the most widely read texts on lunar society.

Godwin’s Man in the Moone appeared in 1638 and was an instant success. His book recounted the picaresque adventures of a young nobleman, Domingo Gonzales. Somewhere in his adventures, Domingo discovered a flock of amazing geese that when properly harnessed could transport him through the air. These geese saved him from harm a couple of times before one day, as they carried him to safety once again, his geese migrated to the moon. After twelve days they arrived at the moon. Godwin wasn’t alone in thinking there might be geese strong enough to carry a human—there were credible reports of giant birds carrying animals as big as elephants and Francis Bacon, that hero of experimental science, considered the possibility of harnessing birds for flight. That’s right, geese migrated to the moon where they wintered before returning in each spring.

Domingo Gonzales on his way to the moon.
Domingo Gonzales on his way to the moon.

When Domingo arrived on the moon, he found it inhabited by incredibly tall, peaceful, beautiful people. Their complexion was perfect, and they were an indescribably beautiful “lunar color.” They spoke a lilting, sing-song language. Domingo spent nearly two years amongst the lunar people before returning to earth.

Godwin’s Man in the Moone was not just a fanciful novel. He, like Kepler, based his description of the moon in the best contemporary knowledge. But unlike Kepler, Godwin envisioned a lunar paradise.

On his journey to the moon, Domingo had been able to observe the daily rotation of the earth. This observation, he claimed, convinced him that Copernicus was right, at least about the diurnal motion of the earth—Domingo remained unconvinced that the sun was at the center of the universe. Also during his trip to the moon, Domingo noticed that as they traveled farther from the earth the force attracting the geese and him to the earth weakened. He concluded that there was some secret, innate force in planets that attracted things to them, perhaps like the force that attracted iron to magnets.

Because the moon was roughly one third the size of the earth, the force of holding things to the moon was considerably weaker. Consequently, plants and animals were many times larger than on earth. An advantage of this weak attractive force, Domingo explained, was how lunar people traveled. They leapt into the air and flapped large feathers to guide their slow descent. In this way they could travel many miles in a single bound.

The lunar society was a utopia: The atmosphere itself was fertile and supported not only the inhabitants but also nourished vegetation, which never needed to be cultivated. Lunar people naturally despised all vice and ever committed any crime. There were no physicians because wounds healed naturally, even a severed head would reattach if placed by on the body in a timely manner. Perhaps most amazing (at least to any of us who have experience with kids these days), all children were wonderful and well behaved—Domingo did point out that the lunar people could tell a bad child at birth and would send these bad children down to “a certaine high hill in the North of America.” Finally, these lunar people seem to be Christians of some sort.

To be sure, Godwin’s Man in the Moone is an imaginative and optimistic description of lunar society—sort of a 17th-century Pandora filled with early-modern Na’vi. His Man in the Moone, like Kepler’s Dream and more recently James Cameron’s Avatar, uses extraterrestrial life to examine contemporary issues and to try to understand our place in the cosmos. In the 1630s they could only look as far as the moon for those aliens. Today, with our more powerful telescopes and CGI techniques, we can look 500 light years or more into the universe.

  1. NY Times article, “Scientists Find an ‘Earth Twin,’ or Perhaps a Cousin” or The Independent’s “Earth 2.0? Astronomers reveal Kepler–186f, the latest planet in a habitable ‘Goldilocks zone’.” NASA’s Kepler webpage on Kepler 186f is more reserved as is the scientific article linked from there.  ↩

  2. World Socialist Web Site has a nice article on Kepler–186f: “Earth-sized planet in a star’s habitable zone confirmed.” By contrast, Sara Seager is keen on exploiting the commercial and economic opportunities that other earths and mining asteroids promise. She suggests that she is already selling her expertise to private companies, Sara Seager’s Tenacious Drive to Discover Another Earth.  ↩

Geology, Fossils, and the Flood

In “The Fossil Record,” module seven of Jay Wile’s Exploring Creation with General Science, we learn that most fossils were hard-shelled animals and were incredibly similar to living animals, that “environmentalists” lie about current rates of extinction, and that catastrophism makes more sense than uniformitarianism. Or, in other words, the earth was covered by a massive flood, evolution does not occur, and “environmentalists” are hysterical, lying, alarmists.

After a brief survey of how fossils form, Wile highlights particular features of the fossil record and draws conclusions from them. First, the fossil record supports the idea of a universal flood since the vast majority of fossils are hard-shelled marine animals. Second, the fossil record shows that evolution does not occur. Wile explains that “many, many fossils” have living counterparts. The living animal and the fossil are incredibly similar. “Based on the fossil evidence,” Wile tells us, “we can conclude that organisms … experience little change,“ certainly not enough change to become a different species. Third, scientists are not to be trusted. They have wrongly concluded that some species were extinct simply because they have not found a living specimen. But we can’t know for sure that living individual isn’t hiding in some rainforest or dark, unexplored corner of the world.[1]

Then, as a purely political aside, Wile discusses rates of extinction. Citing numbers that seem to have come from a World Conservation Monitoring Center report ca. 1992, Wile claims that since 1600 only 484 animals and 654 plants have become extinct.[2] Perhaps he misread the report (or perhaps his source misread the report), leading him to assert that some of these extinctions “were the result of the natural ebb and flow of creation“ and only some due to human activity. The report[3] seems, rather, to blame human action for causing these extinctions above and beyond the background extinction rates. Wile also ignores the tentative nature of these numbers, which by the early 1990s scientists were using them as a sort of minimum approximation. Instead, he boldly claims that in the last 400 years just over 1,100 species have gone extinct and accuses “environmentalists” of “outright lies” when they suggest larger numbers. His use of the slur, “environmentalist,” serves to deny climate change and indirect human responsibility for the extinction of species.[4]

As a sort of preview for the next module, Wile concludes “The Fossil Record” by contrasting once again uniformitarianism and catastrophism. Uniformitarianism with its modest assumptions—geological processes remain largely the same throughout history and the earth is really, really old—and tidy explanations of geological features is somehow deficient. Wile prefers a Rube Goldberg-esque catastrophism.[5] He denies the consistency and regularity of natural processes.[6] Instead, he adopts a framework divided by the Biblical Flood—he devotes an entire page making the case for the universal deluge, sprinkled with a few choice quotations from Genesis 7. The antediluvian period is entombed below John Wesley Powell’s Great Unconformity.[7] Here Wile sketches the basic contours of a flood geology. Slippery uses of terms like evidence, speculate, article of faith, relevant data, and scientific allow him to conclude: “In the end, then, both uniformitarians and catastrophists must speculate. … Neither framework is any more “scientific” than the other.” Despite Wile’s claim, his possibly coherent and certainly labyrinthine his exposition of catastrophism doesn’t make catastrophism scientific.

  1. Wile grants that mammoths are extinct, but that’s about it. I suppose even he had difficulty accepting that somewhere in the wilds of Siberia mammoth herds roam the permafrost just waiting for scientists to discover them. But mammoths are the exception that prove his rule.  ↩

  2. One wonders, or at least I wonder, if Wile thinks that somewhere individuals from this group of 484 animals might be hiding under leaves or lurking in the shadows, evading the searching eyes of scientists.  ↩

  3. Or rather, a preponderance of other quotations purporting to be from a report by the WCMC indicate that the original report highlighted the human causes of these extinctions.  ↩

  4. Wile does say humans caused the extinction of the Passenger Pigeon and the Robust White-eye, but these are unusual.  ↩

  5. The term “byzantine” might apply as well, if not for the farcical aspects of Wile‘s exposition. His ornate description of catastrophism seems better suited for a Monty Python sketch than a science textbook.  ↩

  6. If you are worried that Wile seems to departed from anything resembling “science,” I share that concern. How can a science of geology be constructed on a model that assumes most geological features were produced by singular, miraculous events. How can we know when a geological feature is the result of such miraculous interventions or merely the mundane result of natural processes? What criteria are there to keep “explanations” from becoming simply a matter of making up stories about interesting geological features? Wile’s touchstone is the creation story in Genesis. As a thought experiment, it might be interesting to think how Dr. Jay Wile, PhD in chemistry, would apply a similar approach to “nuclear chemistry,” his area of expertise. Suppose radioactive decay was inconsistent or catalysts randomly lowered activation energy (almost unbelievably, he does seem skeptical about rates of radioactive decay, calling them “wild extrapolation” (you will have to take my word on this since I cannot bring myself to link to his blog post)).  ↩

  7. Of the antediluvian period, Wile thinks only the first three days of the Creation week were geologically important. Despite the 1650 years between Creation and the Flood, “there probably wasn’t a lot of geologically important activity between the end of Creation week and the worldwide flood.” Wile’s position is, at the very least, internally consistent. The Biblical narrative doesn’t include any significant catastrophes between Creation and the Flood. So, accordingly, Wile doesn’t find evidence of any in the geological record. Sure, a few small, local catastrophes “contributed only a little to the geological features below the Great Unconformity,” but on the whole nothing worth noting.  ↩

An Apologist’s Version of the Foundations of Geology

The next module in Dr. Jay Wile’s Exploring Creation with General Science confronts geology. Wile is a young earth creationist who has already accused scientists of loving “radiometric dating because they want to believe the earth is billions of years old.” Unsurprisingly he dismisses uniformitarian geology with its incessant and inexorable changes in favor of catastrophism, a sort of Flood geology:[1]

In my scientific opinion, the most important data support catastrophism, and the data in support of uniformitarianism are rather limited and can mostly be “explained away.”[2]

As appealing as this might be for Wile, even William Buckland might have been hard pressed to accept Wile’s catastrophism. Buckland at least tried to formulate an old earth creationist model that did not unduly privilege the Flood. For Buckland, the deluge could not have deposited all the strata in a single year. Wile doesn’t seem to see that as a problem (more on this in the next two posts).

This module focuses mostly on vocabulary, basic geology terms: types of rock, weathering and erosion, and the Grand Canyon’s Great Unconformity. The real payoff, for Wile, comes in the next two modules. There he presents his case for catastrophism.

This module along with the preceding one and especially the following two seem tangential to his main subject, which subject is basic biology. These four modules serve only to provide him with the space to undermine evidence for an ancient earth and to assert his young earth creationist ideas. Like the first couple modules, which served only to let him undermine well-established scientific findings.

  1. Melvyn Bragg and guests explored the history of catastrophism in a recent In Our Time – Catastrophism. It is worth a listen.

    Note, Wile’s catastrophism has nothing to do with comets or asteroids that might have caused the extinction of dinosaurs. As becomes clear in the next module, his singular catastrophe is the Flood.  ↩

  2. Although Dr. Jay L. Wile, PhD in chemistry, gets points for honesty, we might worry about his rhetorical stance here and its implicit argument from authority. Expertise is not fungible. A degree in chemistry doesn’t, by itself, give Dr. Wile expertise in geology. Nevertheless, in comments like this he asserts his superiority over his middle-school-aged student and their homeschooling parents (assuming the parents read their homeschooling texts carefully).  ↩

Wile on Archeology, Geology, and Paleontology

The first substantive modules in Wile’s Exploring Creation with General Science promises to introduce historical sciences, archeology, geology, and paleontology as a way of introducing “life science.”[1] Wile doesn’t deliver on that promise. Instead, he offers an idiosyncratic method for evaluating historical evidence, which he then applies to the Bible, a critique of methods of dating artifacts, and finally a wildly tendentious claim that the Bible is the best source for studying the history of human life.

Once again, Wile begins reasonably enough, pointing out that we can use archeology to supplement the historical record.[2] But then he goes a step further, characterizing archeology as scarcely more than a handmaiden to history:

archeology’s main strength lies in uncovering and clarifying the history of civilizations for which we do have historical records.

In Wile’s model, archeology confirms or contradict historical evidence, i.e., documents. But it is only one of the ways documents are evaluated. Wile here introduces three tests that “historical science” applies to any document: the internal test, the external test (the domain of archeology), and the bibliographic test. The internal test looks for internal contradictions. The external test evaluates a document against other historical facts, drawn from other historical documents and archeology. The bibliographic test tries to determine if the document is a faithful copy of an eye-witness account or of a reliable report of an eye-witness account. To illustrate these three tests, Wile applies them to the Bible and finds. He explains away contradictions to ensure that the Bible passes the internal test. He cherrypicks archeological evidence that confirms Biblical passages. Finally, he claims that the text of today’s Bible differs little (and only trivially) from the ancient Old and New Testaments and is, therefore, “faithful to the original eyewitness accounts.” All this leads him “to the scientific conclusion that the stories and account in the Bible are more trustworthy than any of the other accounts we have about the Roman Empire and other facets of ancient life!” We might wonder about Wile’s definition of “scientific” here—his three tests from the “historical sciences” come from an old introduction to English literary history and folklore.[3]

Along with illuminating historical documents, archeology helps us learn about humans’ prehistory. But here, Wile cautions, we have to be careful because we have no good way of learning the age of an artifact. Spoiler alert: Wile is a young-earth creationist. The two methods archeologist use to date artifacts—dendrochronology and radiometric dating—are fraught with problems of accuracy and precision. Dendrochronology can be accurate only back to ca. 6600 B.C. Carbon–14 techniques are less reliable, and all but unreliable if the artifact is older than 3,000 years. Yet, Wile concludes:

many scientists love to use radiometric dating because they want to believe that the earth is billions of years old and that man has been living on earth for hundreds of thousands or even millions of years.

It’s fascinating to see Wile whose faith drives his analysis charge scientists of being dogmatic. At a minimum, Wile opens himself to the charge of being blind to his own prejudices. More severely, he reveals his own hypocrisy.[4]

Wile’s three tests, his “scientific” analysis of the Bible, and his rejection of radiometric dating all serve his broader point: the Bible is the best source for understanding all human history on the planet.

Module #5 is a fascinating example of selective logic, vague definitions, non-sequiturs, and unintentionally funny assertions—such as when Wile writes: “If you start deciding to reject parts of biblical history, you have really departed from the science of history and are more or less making up the rules as you go.” The module’s implicit goal reinforces that of the first two modules: distort uncertainties to undermine scientific techniques in an effort foster doubt in and suspicion of scientific results.[5]

  1. “Life science” is Wile’s term for basic human anatomy and physiology.  ↩

  2. Geology and paleontology receive a passing mention and potted definition at this point. The next two modules focus in turn on these two sciences.  ↩

  3. I had never heard of these tests before reading Wile’s book, or at least I had never heard of them labeled “internal,” “external,” and “bibliographic.” Wile does not cite any source for these tests. Some digging around reveals that sometime in the 1970s, an popular apologist extracted them from some obscure book published in 1952 by a scholar who worked for the U.S. Air Force. They have become a set piece in reformed Christian apologetics over the last 50 or so years.

    Wile is like so many other apologists who have used “science” to demonstrate the truth of the Biblical account. Its success depends on a bloated definition of science as well as a selective application of that “science” to the Bible.  ↩

  4. In his history of science survey he accused them of being swayed by arguments from authority. Here again, he perverts a perfectly reasonable warning into something absurd.  ↩

  5. For example, radiometric dating. Yes, radiometric dating is uncertain, sometimes millions of years off. But when it dates objects to billions of years old, the uncertainties are insignificant. Similarly, radiocarbon dating has a degree of uncertainty, but that uncertainty is small compared to the age of the object.  ↩

20-Sided Reviewer’s Die for History of Science

And now, for a little late summer levity.[1]

In an effort to make reviewing manuscripts easier and faster, I put together this little template for the 20-Sided Reviewer’s Die for History of Science.[2] Now, instead of having to read through the entire manuscript, trying to identify and evaluate the argument and sources, you just have to toss a die a few times (see instructions on template).

20-Sided Reviewer’s Die for History of Science, with instructions.
20-Sided Reviewer’s Die for History of Science, with instructions.

A pdf version is available as a download if you want to make your own.

  1. I should emphasize: this is a joke. One that arose during a recent conversation with a colleague about how much time and effort it takes to review a manuscript.  ↩

  2. This die was inspired by the 20-sided die at Pocket Art Director™. The template was clearly adapted (nearly copied—so if you are Pocket Art Director™ and are you upset, let me know so I can remove it) from Pocket Art Director™’s Print My Own template. The “Like” and “Dislike” icons I used were designed by Eugen Belyakoff from the Noun Project: Like and Dislike  ↩