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constantly faces the sun, the horns are pointed toward the west. She is now seen as a bright crescent in the eastern sky just before sunrise. At last the illumined side is completely turned from us, and the moon herself, coming into conjunction with the sun, is lost in his rays. To accomplish this journey through her orbit from new moon to new moon, has required 29} days—a lunar month.
Moon runs high or low. All have, doubtless, noticed that, in the long nights of winter, the full moon is high in the heavens, and continues a long time above the horizon; while in midsummer it is low, and remains a much shorter time above the horizon. This is a wise plan of the Creator, which is seen yet more clearly in the arctic regions. There the moon, during the long summer day of six months, is above the horizon only for her first and fourth quarters, when her light is least; but during the tedious winter night of equal length, she is continually above the horizon for her second and third quarters. Thus in polar regions the moon is never full by day, but is always full every month in the night. We can easily understand these phenomena when we remem. ber that the new moon is in the same quarter and the full moon in the opposite quarter of the heavens from the sun. Consequently, the moon always becomes full in the other solstice from that in which the sun is. When, therefore, the sun sinks very low in the southern sky the full moon rises high, and when the sun rises high the full moon sinks low.
HARVEST MOON.—While the moon rises on the average 50 m. later each night, the exact time varies from less than half an hour to a full hour. Near the time of autumnal equinox the moon, at her full, rises about sunset a number of nights in succession. This gives rise to a series of brilliant moonlight evenings. It is the time of harvest in England, and hence has received the name of the Harvest Moon. Its return is celebrated as a festival among the peasantry. In the following month (October) the same occurrence takes place, and it is then termed the Hunter's Moon. The cause of this phenomenon lies in the fact that the moon's path is variously inclined to the horizon at different seasons of the year. When the equinoxes are in the hori. zon, it makes a very small angle with the horizon ; whereas, when the solstitial points are in the horizon, the angle is far greater. In the former case, the moon moving eastward each day about 13°, will descend but little below the horizon, and so for several successive evenings will rise at about the same hour. In the latter, she will descend mnch further each day and thus will rise much later each night. The least possible variation in the honr of rising is 17 minutes—the greatest is 1 hour, 16 minutes.
In the figure, 8 represents the sun, E the earth, M the moon; CF the moon's path around the earth when the solstitial points are in the horizon-ED when the equinoxes are in the horizon; A MBS the
horizon; Md = Mb = 13°, the distance the moon moves each day. When passing along the path CF, the moon sinks below the horizon the distance ab, and when mov
Fig. 44. ing along the path E D, only the distance cd. It is obvions that before the moon A can rise in the former case, the horizon must be depressed the distance a b, and in the latter only cd; and the moon will rise correspondingly later in the one and earlier in the other.
NODES.—The orbit of the moon is inclined to the ecliptic about 50, the points where her path crosses it being termed nodes. The ascending node (8) is the place where the moon crosses in coming above the ecliptic or toward the north star; the descending node (8) is where it passes below the ecliptic. The imaginary line connecting these two points is called the “line of the nodes.”
OCCULTATION.—The moon, in the course of her monthly journey round the earth, frequently passes in front of the stars or planets, which disappear on
one side of her disk and reappear on the other. This is termed an occultation, and is of practical use in determining the difference of longitude between various places on the earth.
LUNAR SEASONS; DAY AND NIGHT, ETC.—As the moon's axis is so nearly perpendicular to her orbit, she cannot properly be said to have any change of seasons. During nearly fifteen of our days, the sun pours down its rays unmitigated by any atmosphere to temper them. To this long, torrid day succeeds a night of equal length and polar cold. How strange the lunar appearance would be to us! The disk of the sun seems sharp and distinct. The sky is black and overspread with stars even at midday. There is no twilight, for the sun bursts instantly into day, and after a fortnight's glare, as suddenly gives place to night; no air to conduct sound, no, clouds, no winds, no rainbow, no blue sky, no gorgeous tinting of the heavens at sunrise and sunset, no delicate shading, no soft blending of colors, but only sharp outlines of sun and shade.
What a bleak waste! A barren, voiceless desert! The nights, however, of the visible hemisphere must be brilliantly illuminated by the earth, while its phases “serve well as a clock—a dial all but fixed in the same part of the heavens, like an immense lamp, behind which the stars slowly defile along the black sky.”
TELESCOPIC FEATURES.—The lunar landscape is yet more wonderful than its other physical features.