Astronomy

Facts about the Moon



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It’s an odd thing, but established facts don’t last very long.  They always lead somewhere else, usually to more information and a new vantage point, from which things look entirely different and we are forced to rethink the entire matter, including where we stand in it.  This is called learning, and we have indeed learned many facts about the the Moon, humanity's constant companion and inspiration down through the millenia.

Measuring Time

The Moon is not only the most obvious feature in the night sky, it also has cycles that are simple enough to be understood without advanced technology and mathematics, and they happen frequently enough to meet humanity’s time-keeping needs in the short term, as compared to the long-term calendar provided by the Sun in its annual path around the Earth (as it looked to people back in the early days).

As human nomads settled down into the first agricultural communities and began building civilizations, it became enormously important to have some foreknowledge of the best times to plant crops and harvest them, when to expect animal migrations, the times when disaster might strike (bad weather, droughts, eclipses, floods), and so forth.  The possession of this knowledge would also give its owner a measure of power over other people.

Loremasters in individual communities scattered all over the planet must have launched humanity’s first versions of a moon program a thousand times over, documenting the phases of the moon,  breaking their repetition down into units that sometimes were named after the moon—“months,” in English.  Priests began to build things to measure, as accurately as possible, the time from new moon to new moon, roughly 29 days, and carefully gathered enough facts about the Moon to make the first religious calendars, a few of which are still used today and from which most modern calendars are derived.

Other Uses For Knowledge Of The Moon

Some people noticed that women had an internal cycle, vital to human survival, that was similar in length to that of the moon, and suddenly we recognized a Divinity up there (either male or female) who went by various names.  

Others, looking up at the Moon, saw the stars beyond it and started thinking about them for the very first time.  It made them wonder if there was more to Creation than just the Earth and if we were meant to find it. 

On a more mundane level, coastal dwellers began to notice a relationship between the phases of the moon and the ocean tides, and realized that heavenly bodies affected the Earth in subtle ways:  perhaps if these ways could be understood people could travel for a distance out over the wide waters, far enough to find new, wondrous, and rich lands!

Knowledge Grows

After the monthly and lunar eclipse cycles and details of the Moon’s path had been understood and documented, many new facts were claimed about the Moon, but only some them have held up to the present time:

•  The Moon is a spherical rock that reflects the light of the Sun (4th and 5th centuries BC).

•  The major ocean tides are caused by the attraction of the Moon, and their height depends on the Moon’s position with regard to the Sun (2nd century BC).

•  The correct size of the Moon and its distance to the Earth (1st and 2nd centuries AD).

•  The Moon has mountains and craters (Galileo, 1609).

•  Accurate mapping of lunar geography, using trigonometry (Beer and Mädler, 1834 through 1837)

•  Lunar craters were formed from collisions (1870s)

By the 20th century, the advent of astrophotography spurred mapping of the lunar surface.  Between 1960 and 1964, the United States Air Force mapped the whole of the Moon’s near side to a scale of 1:2,000,000.

The Flood Of data

We are afloat in a sea of facts about the Moon today because of a complex of earthly factors that began in the late 1950s, including politics, as in the “Space Race” that began between the United States and the Soviet Union, and advances in technology, chemistry, software engineering, and other scientific fields.

The Soviet Union’s Luna program proved that soft landings were possible on the Moon and brought back the first lunar rock and soil samples.  The Apollo program returned over 2000 such samples and deployed heat flow sensors, seismometers, magnetometers, and laser-ranging reflector arrays at different sites; some instruments, like the reflector arrays, are still in operation today.  Since the 1990s, Europe, China, Japan, India, and the United States have also sent multiple unmanned missions to the Moon to intensively map and study its surface.

We now know enough factual detail to agree that, long ago, the Moon's surface was entirely molten and then it cooled, with heavier, iron-rich minerals sinking down to form the lunar mantle, while lighter materials floated on top and formed its crust.  An intense asteroid bombardment was happening then, cratering the crust and churning it up.  Then, some 3 to 4 billion years ago, melting happened deep in the mantle, and dark basaltic magma was erupted on the surface, filling in many of the largest craters.  The last of these eruptions happened some 1 billion years ago.  In early times, observers on Earth thought these dark areas on the Moon were water, and gave them the Latin name for "seas," maria.  Now we have walked there and know their true nature is not water, but rather, frozen rock.

Controversies

We also have enough facts to disagree, sometimes vehemently.  Depending on who you talk to, there is no water up there; there is some water up there; or there is lots of water up there.  However, everybody agrees that whatever water there is, it will be very hard to extract.  Yet we must do exactly that, if we are to return there, for we can't bring water with us from Earth for lunar colonies

Perhaps that is the basic controversy:  What are we to do about the Moon, now that we know so much about it.  Should we return?  If so, how?  Having returned, should we use the Moon as a nearby resource field (it has much hydrogen and mineral resources) or just as a stepping stone to the stars?

John Marmie, the deputy project manager for NASA’s LCROSS mission (the one where they crashed into one the craters on the dark side of the moon, where there was suspected to be water ice, studied the debris cloud that came up, and indeed found water), put his argument for a return to the Moon to music, including these lyrics:

“Thirst for reason,
A dreamer's eyes we gaze into.
A sense of purpose known by few,
Like finding water on the Moon.

If Galileo had his way,
I'm sure he'd dance upon the stars.
What a wondrous sense of destiny
To be the first to set foot on Mars. “

There is no way humanity can possess all these facts about the Moon and not return to it some day.  That day will probably not come until our viewpoint has shifted once more, and not mere wonder, but also a need to rethink the whole thing drives us upwards, to the Moon and perhaps beyond it, as we seek to find out where we stand among the stars.

Sources:

Brown, Peter Lancaster. Megaliths, Myths and Men:  An Introduction to Astro-Archaelogy. (2000)

Science Buddies.  The Moon and Tides.

Wikipedia.  Moon.

Cadogan, Peter H.  The moon: our sister planet.

NASA.  Moon.

LCROSS. Water on the Moon.


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