The Moon

by Oliver Morton

  Riccioli, like almost every observer after Galileo, interpreted the darker parts of the Moon as watery, distinguishing them with the terms mare (sea), oceanus (ocean), sinus (bay), lacus (lake) and palus (marsh), and added to them terms associated with either seas, the Moon or both. Thus, as well as an ocean of storms and a sea of tranquillity, there is a bay of dew (Sinus Roris) and a bay of rainbows (Sinus Iridum), a marsh of decay (Palus Putredinus) and a lake of dreams (Lacus Somniorum).* Bright regions, meanwhile, were named for landforms—but only those defined by their relation to the sea: terra (land), littus (shore), insula (island) and peninsula. This aspect of his nomenclature did not persist.

  Most striking, though, were the names he gave to craters. In effect he turned his book’s bibliography into his map’s gazetteer: a list of astronomers and philosophers, ancient and modern. Kepler, whose discovery that planetary orbits are elliptical, not circular, laid the ground for Newton’s theory of gravitation, got a fine bright-rayed crater. Tycho Brahe, the Danish astronomer whose meticulous observations allowed Kepler’s discovery, got an even brighter one.

  Tycho had come up with the astronomical system that Riccioli, and the church, favoured at that time—one in which the Moon, the Sun, Jupiter and Saturn revolve around a stationary and central Earth, while Mercury, Venus and Mars revolve around the Sun. This accommodated Galileo’s discovery that Venus, like the Moon, had crescent and gibbous phases and that they waned and waxed in a way that could only be explained if the planet was circling the Sun. Copernicans took this as evidence that planets in general orbited the Sun. Tycho’s system allowed the observation to fit into a world where, though some planets did so, the Earth remained central and stationary.

  Despite favouring Tycho, Riccioli still gave Copernicus a splendid crater of his own. Indeed, the astronomer Ewen Whitaker, whose work on the history of lunar mapping is invaluable, suggests that the prominence given to Kepler, Copernicus and, most notably, Aristarchus—the ancient Greek who first suggested that the Earth circled the Sun—in Riccioli’s scheme reflects a closet Copernicanism, one that he could not avow in the text but could at least hint at in his map.* This is, at best, a hunch. And even if taken at face value, with no hidden agenda, the map shows how revolutionary the times were. An astronomer had taken it upon himself to name the features of the Moon not after great nobles or churchmen but after scholars like him: a bold claim for the authority of knowledge, properly acquired. And that claim is particularly important in light of the fact that many of those scholars, and most of those who got the most spectacular namesakes, were moderns, not ancients. Riccioli’s Moon was a celebration of new learning by new people.

  WHILE RICCIOLI WAS PEOPLING MOON MAPS WITH ASTRONOMERS, others were filling the Moon itself with Moon people. A principle of divine economy—God would not be wasteful in his creation—led many to conclude that, if there were other Earths, there must be life on them. This is the burden of “The Discovery of a World in the Moon”, published in 1638 by John Wilkins, an attempt to prove the Moon both habitable and inhabited. If they were inhabited, they must have stories. Thus for Copernicans and their fellow travellers, fictions of the Moon became, like drawings of the Moon, a way to expand on its worldliness, while also demonstrating the planetary nature of the Earth, waxing and waning in the lunar sky.

  The wonder of earthlight, a rich signifier of the Earth being to the Moon what the Moon was to the Earth, was a frequent theme. Kepler talks about it in his “Somnium” (1634; “The Dream”), where earthlight mitigates, on the nearside, some of the climatic harshness resulting from 14-day days and nights. In Francis Godwin’s “The Man in the Moone”, published the same year as Wilkins’s book, the protagonist, Gonsales, finds that most lunar life takes place lit only by earthshine; when Earth and Sun are both in the sky, the world is too much for all but its largest and noblest inhabitants; the rest all sleep through the long days.

  The people on Godwin’s Moon are large, wise and Godly, a great relief to him; when he cries out “Jesus Maria”, the natives fall to their knees, and he rejoices at their kinship in Christ. An Earth-like Moon in a Godly universe, as Adam Roberts points out in his “History of Science Fiction” (2016), raised pressing new questions: are its inhabitants saved? Can they be? What does Christ’s sacrifice mean in a universe far grander than that of the schoolmen? Must the people of the Moon take Communion?*

  It was possible that the pure souls involved might be human—that the Moon might be materially the same as the Earth, as the Copernicans writing about it believed, but on a higher spiritual plane. Wilkins suggested that the Moon might be a “Celestiall Earth, answerable, as I conceive, to the paradise of the Schoolmen… this place was not overflowed by the flood, since there were no sinners who might draw the curse upon it”. Cyrano de Bergerac, on visiting the Moon, found Eden to have been transported there, lock, stock and apple. He rather lowered the tone by making off-colour jokes about his trouser serpent to his local guide, the prophet Elijah.

  There are echoes of Plutarch and his Moon full of purified souls here, and echoes of the association with death, too. There is also, though, the added Christian complication that a world of, or for, pure souls is to be found in the prehistoric past as well as hoped for in one’s personal future. Thus, early in the history of stories about the Moon as new world, it becomes an old world, too. This dichotomy—ancient in itself, new to humanity—has remained a part of lunar fictions from then until now.

  These contradictions of ancient and modern draw the Moon into a set of Earthly writings. It is not the only “other Eden, demi paradise” of the era’s imaginings; European voyages of discovery regularly read strange islands as new Edens. To sail the oceans was to travel from the used-up and known to the new and unspoiled: to the “wooded island” of Madeira or the “fortunate islands” of the Canaries, green and garden-like. It is largely as a variation on such an island theme that the Moon enters the literature of the age, part of a more general literature of fantastic voyages and of unusual isolates of humanity—a literature that includes Thomas More’s “Utopia” (1516) and Shakespeare’s “The Tempest” (c. 1610)—places of perfection and strangeness of magic and malformed mooncalf natives. In “Somnium” the Moon is explicitly referred to as an island; Godwin’s Gonsales is an explorer who gets to the Moon from Saint Helena, at the time England’s byword for the Edenic. His book’s influence is seen in subsequent strange-islands-as-inquiries published by Defoe, Swift and others.

  It is worth noting that in all these stories it is people from the Earth who go to the Moon. For most of the planet, the 17th century was not an Age of Exploration but rather an Age of Being Explored by Europeans. But it was the Europeans who were writing Moon stories, and few imagined themselves on the receiving end of exploration. When they did, centuries later, it would be to Mars, not the Moon, that earthlings would look for invasion.

  The Moon thus became the farthest skerry of an archipelago of deep thought and high jinks, a place it held for centuries. These were not realistic fictions. Whether it was indeed habitable and what it might really be like, the questions which exercised Wilkins and Kepler, were, within a few decades, of relatively little interest. The Copernican revolution which Wilkins had been prosecuting in prose had by then been won by other means. By the end of the 17th century, the manner in which the Moon represented a new way of seeing the cosmos had changed from being a question of what it might be to live there, or how it looked, to a matter of the force that governed its movement.

  ISAAC NEWTON’S “PRINCIPIA” OF 1687 TIED THE MOON TO THE Earth not by similarity but by gravity. Kepler had discovered that the planets moved in ellipses round the Sun; in the decades which followed it was confirmed that moons did the same around the planets fortunate enough to have them. He also found that orbiting objects moved faster when closer to the object they were orbiting than they did when farther away in a mathematically well-defined way. Working from these empirical laws, Newton produced a theory of how mass was attr
acted to mass—Earth to Sun, Moon to Earth, apple to Earth—in a way which depended on the square of the distance between them, a universal gravitation which, like the sight of the Moon from a kitchen window, unites the cosmic and the domestic.

  This marriage of heavens and Earth was nowhere more visible than in the tides. To understand how gravity produces them, imagine an Earth completely covered by water. The water level directly under the Moon will be higher than average because the waters there, being closer to the Moon, are more strongly attracted to it than are the waters elsewhere: it is pulling them away from the Earth.

  Somewhat counterintuitively, the water level on the side of the Earth directly opposite the Moon is similarly raised. This is because those waters, being farthest from the Moon, are the least strongly attracted to it—but the attraction they are feeling the least of is one that, in this geometry, pulls them towards the Earth. The strongest force pulling away from the Earth and the weakest force pulling towards it thus have much the same net effect. The result is something like a spherical volleyball Earth encased in a Moonwards-pointing rugby ball of water.

  The Sun, too, creates tides, in much the same way: there is a bulge to sunward and another to anti-sunward. They are, though, smaller bulges. Though the Sun is 30 million times more massive than the Moon, it is also 400 times farther away, and the way that Newton’s gravity works means that the distance counts against it more strongly than the mass counts in its favour.* The two bulges line up when the Earth, Sun and Moon do—that is, when the Moon is either very close to the Sun in the sky or directly opposite it. These are the spring tides associated with full Moons and new Moons; the way in which Newton’s theory explained both their existence and their amplitude was one of the most impressive ways in which it brought the universal down to Earth.

  The tides are in practice much more complicated than this. The Earth and its waters rotate every day; the point beneath the Moon makes a circuit only once a month; the point beneath the Sun only once a year. Thus the waters are endlessly trying to keep their tidally ordained shape while the solid Earth turns within it. This turning topography of shores and seabed means that the reach, frequency and precise timing of the tides vary from place to place. In the middle of the Pacific, with no local land to mess things up, the tidal reach is less than a metre. In the English Channel, where the bulge is trying to get from the Atlantic Ocean to the North Sea every 12 hours, the reach can be seven metres or so.

  To Newton’s irritation, his theory did not at first allow all these subtleties to be worked out from first principles; for a century or more, tide tables continued to be calculated empirically. But gravitation did mark a decisive shift to a worldview in which the universe had the characteristics of mechanism, in which Copernicanism was unavoidable and in which learning had new power. In so doing it also unburdened the Moon of the requirement to be Earth-like it had laboured under when it was part of the basic case for the Earth’s planetary nature. The Moon was free to be what it was, and what it was came to seem ever less hospitable.

  The changes to the Moon’s face that Gilbert had planned to record turned out to be, as he had suspected, slight changes in which parts of its surface were visible, changes that Kepler’s laws and Newton’s theory explained precisely. But there were no changes to be seen in what was on that surface. There were no weather patterns that altered with the seasons. There was no snow. The “seas”, on close inspection, turned out to be peppered with small marks, and not completely flat. Odd water, to say the least.

  Nor was there air. The idea that the Moon had an atmosphere its inhabitants could breathe had been crucial to Wilkins’s arguments for a “world in the moon”. Indeed, his book is the first to ever use the word atmosphere in its modern sense. There had been no atmosphere on the Earth before: just air, an element that sat above the land and sea. Only when it became a necessary condition for life on another planet did air develop a planetary mode of being as an envelope that could be wrapped around any body of sufficient size. Only after atmospheres became a way of understanding air elsewhere did they become a way of understanding it on Earth, too.

  Unfortunately, Wilkins’s evidence for the Moon’s atmosphere—the blurriness of features on the lunar surface—was in fact evidence of the Earth’s. By the late 17th century, studies of what happened when the Moon, moving across the sky, obscured a distant star seemed to prove this. The star would not fade or flicker as it approached the limb of the Moon, as it might have done were it being seen through ever more of the Moon’s obscuring atmosphere. It simply vanished.*

  The lack of an atmosphere confirmed what observation was already making clear about the maria: they were dry. One of the key discoveries of knowledge’s mechanistic turn was that though nature might, as Aristotle was held to have taught, abhor a vacuum, machines—“air pumps”—could create one. When they did so, liquids under the vacuum boiled away, whatever the temperature. An airless Moon must be a sea-less one, too. It thus seemed an ever more lifeless one, to boot.

  None of this devalued the Moon as a site for speculation and Swiftian satire. It did, though, provide a new object for that satire—the fanciful scientist attending to the high-flung matters of the Moon and ignoring the everyday. Thus in Samuel Butlers’s “The Elephant in the Moon” (c. 1670), astronomers mapping the lunar surface

  To make an inventory of all

  Her real estate, and personal;

  And make an accurate survey

  Of all her lands, and how they lay,

  As true as that of Ireland, where

  The sly surveyors stole a shire

  are amazed to discover on its face not merely armies of tiny beings but also a very big elephant:

  It is a large one, and appears more great

  Than ever was produc’d in Afric yet;

  From which we confidently may infer,

  The Moon appears to be the fruitfuller.

  As they rush off to right their papers, though, a servant learns the truth when he looks not through but into the telescope.

  He found a small field-mouse was gotten in

  The hollow telescope, and shut between

  The two glass-windows, closely in restraint,

  Was magnified into an Elephant.

  The armies were gnats, the mighty monster lowly vermin; instead of astronomers turning the cosmos upside down with their instruments, the social order is overturned by smart servants with foolish masters. A similar sentiment shapes Aphra Behn’s play “The Emperor of the Moon” (1687), in which Doctor Baliardo refuses to let his daughter and niece marry men from Earth because his vast telescope has revealed to him, he thinks, that the men of the Moon are more advanced, and thus preferable. He has clearly read Lucian, Wilkins, Godwin and more besides, but learning has not made him wise: “Lunatick we may call him without breaking the Decorum of good Manners,” says the servant Scaramouche, “for he is always travelling to the Moon.”

  The young women enrol Scaramouche and his fellow skivvy, Harlequin, in a subterfuge to convince Baliardo that their suitors, Don Cinthio and Don Charmante, are just the sort of Selenites, as Moonpeople are often referred to, that he wants them wooed by—indeed, that they are the Emperor of the Moon and his brother, the King of Thunderland. Kepler and Galileus are brought on as character witnesses, and much hilarity ensues—as does great spectacle, with stage machinery as advanced as any of the time.

  The possibility of taking the audience to the Moon has since often led to new excesses and subtleties of the spectacular. Georges Méliès’s “Le Voyage dans la Lune” (1902; “A Trip to the Moon”) used the new magic of cinema to show the Moon as a realm unlike any other; “A Trip to the Moon”, a literally sensational fairground ride that opened in 1903 on Coney Island, led to fun fairs and amusement arcades across the world becoming known as Luna Parks; Kubrick’s “2001: A Space Odyssey” (1968), with its anodyne airline elegance settling weightless into savage emptiness, set the style for later special effects extravaganzas while outdoi
ng them in substance.

  That “The Emperor of the Moon” led the way in uniting the mechanisms and spectacles of the stage and the mechanistic spectacle of nature was not a coincidence. Behn had recently translated into English a very popular French book on worlds beyond, Bernard le Bovier de Fontenelle’s “Entretiens sur la Pluralite des Mondes” (1686; “Conversations on the Plurality of Worlds”). In a series of dialogues between a philosopher and a noblewoman, held in a moonlit garden, Fontenelle lays out his ideas of a Copernican cosmos and its possible inhabitants. The idea that wonders of the world have hidden mechanisms, whether in the observatory or on the stage, and that few have the expertise necessary to see them—Doctor Baliardo certainly doesn’t—is a theme in both works. As Fontenelle’s philosopher puts it to his marquise:

  Nature is a great Scene, or Representation, much like one of our Operas; for, from the place where you sit to behold the Opera, you do not see the Stage, as it really is… the wheels and weights which move and counterpoise the Machines are all concealed from our view. [T]here is not above one Enginier in the whole Pit, that troubles himself with the consideration of how those nights are managed.… You cannot but guess, Madam, that this Enginier is not unlike a Philosopher.

  “MICROGRAPHIA” (1665), THE FIRST BOOK PUBLISHED BY THE Royal Society, is famous for its exploration of hidden worlds through its spectacularly rendered images of life as never magnified before: a grain of pollen, a fly’s wing, a louse reproduced at the size of a page. But its author Robert Hooke—an engineer not unlike a philosopher, enemy to Newton and friend to John Wilkins—was interested in magnifications of worlds larger and more distant, too. “Micrographia” contains an image of the crater Hipparchos and its surroundings, remarkable both for its extremely fine detail and for being one of the first images of a specific feature on the Moon rather than of the Moon as a whole.