magdes13

What the Moon actually is has interested people for
millennia, at least. In pre-Christian times the celestial
bodies were not just divine, but in some views the
divinities themselves. The Moon, being close, bright
and highly regular in its phases and position, was
thought to influence the Earth in many ways, and so
was thought to be a cosmic power with an identity and
being, in different aspects, of its own.
The ancient Greeks were interested in what the
heavens were actually made of and how they were
structured, and they propounded as many theories of
the Moon as any other planet. Parmenides himself
indicated our modern understanding of moonlight:

nightshining
round earth
a wanderer with borrowed light

Others thought the Moon was merely a stone. Some
thought it was a stone whose pores leaked light from
the heavenly world. Opinion differed on whether the
Moon was flat or spherical. Aetius reported that the
Pythagorean, Philolaos, had said the Moon was
Earthlike and supported plants and animals fifteen
times larger than terrestrial plants and animals.
Others explained that, like all the objects in the sky,
the Moon was made of the celestial fire, a pure,
ethereal fire as opposed to the material fire found on
Earth. This belief was held widely well into the
Renaissance, and provides one of the main metaphors
in Dante's celestial cosmology. On leaving Eden at the
top of Mount Purgatory to embark for heaven, Dante
and Beatrice pass through a final purifying wall of fire
into the sphere of the Moon.
In the fifteenth century, da Vinci thought the changes
he detected in the Moon's surface appearance were
caused by clouds rising from water. With inferences
like this, modern, inductive, observational science
begins. Galileo, looking through his telescope,
changed the world's lunar theories for good. He
thought the dark areas he saw were literally large
bodies of water, and he called them "seas." In 1651
Giambattista Riccioli followed Galileo's lead when he
mapped and named the dark areas as bodies of water,
for example, Lacus Somniorum, the Lake of Dreams,
and Mare Tranquillitatis, the Sea of Tranquillity

(site of Apollo 11's landing). He named craters after
philosophers and scientists, and his nomenclature
became generally accepted. But he thought the names
merely apt conventions. For religious reasons, he
believed neither water nor inhabitants existed on the
Moon. Riccioli's Christian conviction was a direct
descendant, coming down through Aristotle, St.
Augustine, Dante and other religious thinkers, of the
sense that the stars and planets are made of a divine,
immaterial substance.
As the methods of objective science gained authority,
the Moon's divinity dissolved. Reputable eighteenth
century astronomers conjectured that the Moon was
Earthlike and had an atmosphere and grew plants. An
early nineteenth century German astronomer
speculated that the rilles, long cracks in the Moon's
surface, were roads, and announced at one point that
he had discovered a lunar city. Soon afterward, the
astronomers Beer and Madler explained the Moon's
surface features in detailed geological terms, and the
modern view of a dead, rocky Moon settled into place.
To be sure, no one was unequivocally certain about
the Moon's deadness. Peculiar changes of light, for
example, that could not be objectively explained,
continued to occur on the Moon. A reddish light glows
in some craters from time to time, unpredictably.
Astronomers call these glows "Lunar Transient
Events," but have no idea what they are. They still
occur, unexplained, today. Astronomy textbooks give
the general feeling that the glows are illusions of some
kind that are either minor physical peculiarities or
more likely don't concern science at all.
We do know, now, that the Moon is a lifeless ball of
rock. Shortly before Apollo 11 landed on the Sea of
Tranquillity in July 1969, most scientists were
reasonably certain that the Moon was airless and
waterless, rocky rather than icy. Apollo 8 had flown
around it 10 times at Christmas of 1968 and said so.
The astronauts described pretty much exactly what the
scientists expected they would.
Only the fine details were still uncertain. For example,
there was concern that the Moon might be harboring
alien microbes with the potential to cause mass
infection on the Earth, so mission planners
quarantined the astronauts after the first few Apollo
landings. Some geologists were concerned that Moon
rocks suddenly exposed to oxygen in the spacecraft
might burst into flames. At least one reputable
scientist was convinced that the Moon was covered
with a very light powder, into which Neil Armstrong,
Buzz Aldrin and the Eagle would disappear forever.
But in general the most conventional theories were
borne out. Eagle landed on firm soil. The astronauts
found only rocks and dust. Gravity was low. Nothing
moved that the astronauts did not kick up themselves.
The Moon's mountains and plains looked different
from any Earth landscape, but this too was generally
predictable. Armstrong reported that the landscape
appeared amazingly sharp and clear because of the
lack of atmosphere, but he found it difficult to judge
sizes and distances because there was nothing familiar
for comparison. In brilliant sunlight the rolling land