Moon

a heavenly body revolving about the earth. The moon is not a star, nor is it a planet; it is a satellite. The origin of the moon has been a mooted question. It is now considered that it is of solar, not terrestrial origin; that it was thrown off by the sun, and that after traveling for a time about the sun as a small planet, it came within the influence of our earth and was captured by the larger planet, since which time it has revolved about a new center. It is held that the earth never rotated with sufficient velocity to throw off the moon. Next to the sun, it is the heavenly body of most interest and importance.

The moon travels about the earth in an orbit about 338,840 miles distant. Its orbit is more elliptical than that of the earth, and its average distance from the earth is about 1/390 of the earth's mean distance from the sun. In its orbit the moon travels at an average rate of 2,287 miles an hour, and completes its circuit in a trifle over twenty-nine and one-half days. It turns on its axis once each sidereal month, and thus keeps the same side toward us all the time. The man in the moon is nearly the same that the children of Israel saw in their wanderings. The diameter of the moon is about one-fourth that of the earth; forty-nine moons would equal the earth in volume and eighty-one would weigh as much. The density of the moon is 3.4; of the earth 5.6.

The moon has no light of its own. It shines by the light of the sun. The half of the moon that is in the light of the sun is called its face. Twice a month the sun, earth, and moon are nearly in a line. At the moment when the moon crosses this line we cannot see any part of its bright face. Astronomers then say the moon is new. In a day or two we see a crescent rim and speak of the new moon. In a week the bright portion becomes a semicircle. In another week the moon is on the side opposite the sun, and we see it full in the face and speak of a full moon. As Tennyson puts it,

The visible portion then diminishes to a semicircle and finally to a new moon again. In the latitude of St. Louis the moon rises and sets later each day, by from twenty-three to seventy-seven minutes. Children living in northern Europe see the moon at certain seasons for an entire day at a time. The full moon that comes the month of the autumnal equinox seems to shine with a peculiarly soft, refulgent light. While nearly full it rises for several successive nights at about the same hour and is called the harvest moon. The following moon is called the hunter's moon for a similar reason.

Moonlight is not infrequently strong enough to read by, but it is not over one six hundred thousandth part as strong as sunlight. If the sky were paved with lights equal to that of the moon, they would not yield over one-eighth as much light as is derived from the sun.

The moon appears to be without an atmosphere. As its days and nights are fourteen of our days in length it is evident that the noon hour is intensely hot and midnight frightfully cold. Under a telescope the surface of the moon presents a pitted, small-pox appearance, due to the presence of the craters of extinct volcanoes. Many of these craters are from five to ten, twenty, fifty, sixty, or even one hundred miles in diameter. One of the largest has been named Copernicus in honor of the great astronomer. The weight of opinion is to the effect that the surface of the moon is of barren rock without water, snow, vegetation, seasons, or even storms. Present investigations are being carried on by means of telescopic photographs.

A foolish notion once prevailed that moonlight was a cause of madness, whence the Latin term of lunatic and the English term, moonstruck.

The moon has always been a favorite with children. The man in the moon with his round, good-natured visage seems to look down kindly on upturned faces. Jean Ingelow has a pretty conceit in her Seven Times One:

See Tides; Eclipse; Lunacy