MOON (Luna, ]) ), in Astronomy, one of the heavenly bodies, usually ranked amongst the planets; but with more propriety accounted a satellite, or secondary planet. See Astronomy.

Amongst the ancients, the moon was an object of particular homage. By the Hebrews she was more regarded than the sun, and they were inclined to worship her as a deity. The new moons, or first days of every month, were kept as festivals amongst them, and were celebrated with the sound of trumpets, with entertainments and sacrifices. (See Numb, xviii. 11, x. 16; 1 Sam. xx. 5-18). People were not obliged to rest on these days. The feasts of new moons were a miniature representation of the feast of trumpets, held on the first of the month of Tisri, which was the beginning of the civil year. The Jews not being acquainted with the physical causes of eclipses, looked upon them as signs of the divine displeasure. The Grecians looked upon the moon as favourable to marriage; and the full moons, or the times of conjunction of sun and moon, were held the most lucky seasons for celebrating marriages, because they imagined that the moon had great influence over generation. The full moon was held favourable for many undertakings by the Spartans; and no motive could induce them to enter upon an expedition, march an army, or attack an enemy, until the moon was full. The moon was supposed, both by Greeks and Romans, to preside over child-birth. The patricians at Rome wore a crescent on their shoes, to distinguish them from the other orders of men. This crescent was called lunula. Some say it was of ivory, others that it was worked upon the shoe, and others that it was only a particular kind of fibula or buckle.

Harvest-M00N. It is remarkable that the moon, during the week in which she is full in harvest, rises sooner after sunset than she does in any other full moon week in the year; and by doing so, she affords an immediate supply of light after sunset, which is very beneficial to the farmers for reaping and gathering in the fruits of the earth. Hence they distinguish this full moon from all the others in the year, by calling it the harvest-moon. Infiuence of the Moon on the Human Body. Dr Mead was a believer in the influence of the sun and the moon on [7:15:442]the human body, and published a book entitled De Imperio Solis ac Lunae in Corpore humaìio ; but this opinion has been exploded by most philosophers, as equally unreasonable in itself, and contrary to fact. As the most accurate and sensible barometer is not affected by the various positions of the moon, it is not thought likely that the human body should be influenced by them. Several learned and ingenious men, however, still consider Dr Mead’s doctrine as far from being unfounded.

Moon, influence of, on the earth’s atmosphere. It has been the opinion of the vulgar in almost all ages and countries, that the changes which take place in the state of our atmosphere, or the changes of the weather, depend, in a great measure, on certain situations of the moon. It can scarcely be doubted that an opinion so generally received must be founded on something more than fancy or prejudice; and indeed the observations of meteorologists have contributed materially to favour this opinion.

From the observations of Signior Toaldo, made at Padua, during fifty years, on the state of the weather, which corresponded to certain changes of the moon, he found that these changes were always accompanied by good or bad weather; and he at length became enabled to foretell, with some degree of certainty, what would be the state of the atmosphere which should follow any situation of the moon. There are ten situations of the moon, which, according to Toaldo, are capable of producing a sensible effect upon the earth’s atmosphere. These are the syzigies, or new and full moon; the quadratures; the apsides, or apogee and perigee; the lunistices, or those points when the moon is nearest to our zenith and at the greatest distance from it; and the moon’s equinoxes.

He also calculated a series of probabilities that a change of weather will take place on the approach of any one of ten situations, and these he expressed in a tabular form, as follows:
[table]

The observations of Μ. Lamarck, though they confirm the opinion of the moon’s general influence on the atmosphere, do not agree with those of Toaldo, as to the situations of that luminary which correspond to the changes of the weather. He could not find that agreement between the syzigies and quadratures of the moon and a change of weather which has been so much dwelt on by Toaldo; but he is of opinion, that we are to consider the declination of the moon as the principal cause of her influence on the atmosphere.

Lalande had conceived the idea that when the moon entered the northern hemisphere, or had north declination, the weather was most likely to be cold and dry, and that when she passed to the south of the equator, it was likely to be rainy. The observations of Lamarck, however, tend to establish the contrary opinion.

Lamarck considers the two following principles as established by his observations, viz. “1. That it is in the elevation of the moon above, and her depression below, the equator, that we are to search for those regularly varied effects which she produces on our atmosphere. 2. That the determinable circumstances which conspire to increase or diminish the moon’s influence in her different declinations, are her apogees and perigees, her conjunctions with and oppositions to the sun; and, lastly, the solar solstices and equinoxes.”

Considering that every lunar month, or every revolution of the moon in the zodiac, may be divided into two distinct portions, each containing about fourteen days, and each giving occasion to a particular atmospheric constitution, we may assume these as two circumstances of importance in meteorology, and call the one the boreal or northern constitution, being that in which the moon passes through the six northern signs of the zodiac, and the other the austral or southern constitution, being that in which she traverses the six southern signs.

Lamarck was convinced by observation, that in these climates, during a boreal constitution, there chiefly prevailed southerly, south-westerly, and westerly winds, though sometimes, in the summer, the winds passed to the southeast. In general, during this constitution, the barometer exhibits only moderate elevations of the mercury; most commonly the season is rainy or moist, and the air is loaded with clouds. And, lastly, it is particularly during this constitution that we observe the effects of storms and tempests, when the causes which occasion them become active. On the contrary, during an austral constitution, the winds which chiefly predominate blow from the north and north-west, and in the summer north-east, and even easterly winds prevail. In general, during this constitution, the barometer exhibits considerable elevations in the column of mercury, at least if the wind be not very strong; the weather is then most usually clear, cold, and dry, and in the summer it is seldom, we might almost say never, during this constitution that storms are formed.

These atmospherical constitutions are not, however, so permanently characterized as to render it easy to distinguish them at all times by the state of the atmosphere. The atmospherical air is a moveable fluid, and so easily displaced, that it is not surprising that in the temperate zones, where, from various causes, which counteract the regular influence of the moon, and tend to alter its effects, the influence of the heavenly bodies acts less strongly than between the tropics.

The perturbations which these variable causes produce on the regular effects of the influence of the moon on the atmosphere, occasion many variations in the two atmospherical constitutions which we have been describing; and this is doubtless the reason why they have been hitherto disregarded. Lamarck positively asserts, that these perturbations, although frequent, and sometimes very considerable, do not prevent the character of each of these constitutions from being remarked in the greatest number of cases. The probability which he finds, according to his observations, is estimated at five out of eight; that is to say, out of forty-eight atmospherical constitutions comprehended in the lunar year, he estimates that there will be found at least thirty agreeing with the principles pointed out in his memoir; and he adds, that amongst the disturbing causes which modify the before-mentioned effects, several maybe foreseen, and perhaps even appreciated as to their quantity of effect. He considers what is here pointed out as a fact, that is, as an order of things which any one may prove by observation.^[1. See Journal de Physique, vol. iii.; and Nicholson’s Journal, 4to, vol. iv. ]

Μ. Cotte also bestowed much attention on the subject of the moon’s influence; but he appears to think that our observations are not sufficiently numerous nor accurate to deduce any thing like a correct theory, and he is not disposed to go as far as Μ. Lamarck. He agrees in general [7:15:443]with Mr Luke Howard’s observations on the moon’s influence. During the space of thirty-four years and five months (from the 1st of January 1768 to the 22d of May 1802), he noted the ascending and descending direction of the barometer in each of the syzigies and quarters of the moon which occurred during that period of time. He states the total sum of the elevations and depressions of the mercury at each of the phases as follows:
[table]

For some further account of opinions on this subject, see the article Weather.