The Moon is linked with the oldest and most persistent superstitions

Now that we know what ignorance about the Moon exists in our day of supposed enlightenment, we can hardly be surprised at the fancies formed in the minds of our ancestors. The Moon is linked with the oldest and most persistent superstitions. "Plant sweet peas on Saint Patrick's day in the dark of the Moon." "Hog's meat will not keep if left hanging where the Moon will shine on it." "After a moonlit Christmas, expect a lean harvest and a fat graveyard."

Close investigation has revealed no effect from a full Moon upon pork, sweet peas and Christmas (lovers and poets always excluded). Nor does it seem to have any influence over the weather, though that seems a more credible superstition. Recent discoveries, however, have almost proved that the altitude of the Moon affects our radio reception. There may be something to the other ideas which we have laughed to scorn.

Whether any of the superstitions hold true or not, there can be no doubt that the Moon was indirectly responsible for a great many decisions of ancient and modern times. "Moonshine" is a disrespectful name for bad whisky, but the Persian and Hindu "soma" had the same origin and meaning. The ancient Hindus thought of the Moon as a vessel full of sacred wine, a kind of miraculous pitcher that waned as it was drunk, but always filled again. They seemed to consider it their duty to help by consuming as much of the liquid as possible. In the name of the Moon they drank on all state occasions. Herodotus tells us that the Persians deliberated upon weighty affairs when they were under the influence of wine and then reconsidered when they were sober. That was not such a bad custom. "But," continues Herodotus, "sometimes they deliberate when they are sober and decide when they are drunk."

So much for effects that the unsuspecting Moon has had upon mankind.

In spite of all the confusion, ancient and modern, the explanation of the phases of the Moon is really quite simple. The shadows of the Earth have absolutely nothing to do with the case. Terrestrial shadows cause lunar eclipses; and these eclipses occur only when the Moon is full. The Moon does not have any light of its own:

"The moon above, the Church below

A wondrous race they run,

But all their radiance, all their glow,

Each borrows from its sun."

This borrowed glory is the cause of the phases. They depend entirely upon the relative positions of the Sun, Moon and Earth.

The Sun is 93,000,000 miles away. It casts its light indiscriminately on everything in the solar system, on planets and their satellites alike; but it can only illuminate the surfaces turned directly to its rays. The Moon is only 240,000 miles away and it revolves around the Earth. Once every month it comes almost between the Earth and the Sun. At that time no part of the Moon can show its reflected light toward the Earth. It is invisible and dark. Echoing old calendars, we call it "new."

The first evening after a new Moon we can see a thin crescent of the light which the Sun continually throws over half the Moon's surface. The Moon is moving away from the direct line between Earth and Sun; it rises later than the Sun now, and sets later. As it moves farther eastward in its regular counterclockwise revolution, more and more of the shining surface comes into our view, and the Moon progresses through its phases, first quarter when the Earth is at right angles to the Moon-Sun line, full Moon when the Moon is opposite the Sun, last quarter with a right angle again, then the last crescent and the old Moon becomes new.

"You are two book-men: can you tell by

your wit

What was a month old at Cain's birth

that's not five weeks old as yet?"

That was a good riddle when it was first invented; but it was invented several thousand years before Shakespeare put it into Love's Labour's Lost.

Of course the rising and setting times of the Moon are directly related to its phases. Natural laws, rather than providence, give us a whole night of full Moon, and let the dark Moon hide its face with shame during the day. We see all the light on the Moon's surface when it is opposite the Sun; and when it is opposite the Sun, it must obviously rise about the time when the Sun sets, and set almost in accordance with the rising Sun.

The Sun's rays are falling impartially on everything within the solar system. They strike the Earth as well as the Moon, and we reflect back the light. Sometimes when the Moon is young, and its crescent thin, we can see the unlighted part of the Moon emitting a faint glow, hardly more than enough to outline it against the sky. The faint shine is caused by the sunlit Earth, reflecting its light on the Moon; and the Moon again is reflecting it back to us. We combine with our satellite to form two mirrors, each catching the Sun's light, tossing it back and forth.

This "Earthshine" occurs only at a crescent Moon for we must be able to see the Moon; it must not be shining too brightly to obscure the glow; and part of the daylit Earth must be turned toward the Moon. If these three conditions are fulfilled, we can see our own reflection in the face of our satellite.