ECLIPSE.
When the moon, during her motion from east to west, passes over any planet or fixed star, so as to hide it from the earth, the phenomenon is called an occultation of the star or planet. As all the planets, however great be the inclination of their orbits, must some time or other come near the ecliptic, and consequently near the moon's orbit, all of them may suffer an occultation by the moon ; but it is only those fixed stars which lie in the moon's path that can be eclipsed by this luminary. All those stars, whose latitudes, whether north or south, do not exceed 6° 36', may suffer an occultation somewhere on the earth ; and if their latitudes do not exceed 4° 32', they may undergo an occultation on any part of the earth. In order to know if an occultation will happen. we must find the time when the longitude of the moon is the same with the longitude of the stars ; and if the differ ence between the moon's latitude and that of the stars should exceed 1° 37', no occultation can take place. If the difference be less than 57', an occultation must take place to sonic parts of the earth. The most remarkable stars that can suffer an occultation by the moon, or to which the moon can make a near appulse, are.
. _ The longitudes, latitudes, and magnitudes, of these stars, will be found in the Catalogue of Stars at the end of this article. See OCCULTATION.
As the moon moves from west to east about 13 de grees every day, she rises generally about 50 minutes later every evening. In the autumnal season, however, the full moon seems to rise for several nights succes sively at the time of sunset, and is then called the harvest moon. If the moon moved in the plane of the equator, she would rise exactly 50 minutes later every night, as the equator makes equal angles with the horizon at all times of the day, and at every season of the year. But
as the moon revolves in an orbit considerably inclined to the equator, and nearly in the plane of the ecliptic, this orbit makes different angles with the horizon, as may be seen in a common globe. If the moon is in that part of her orbit which makes the greatest angle with the horizon, a smaller portion of her orbit will ascend above the horizon during a given time, than when she is in that part of her orbit which makes the least angle with the horizon. When the moon is in the 23d de gree of Leo, 13 degrees of her orbit, which she describes in a day, rises above the horizon in the space of 1 h 17'; and therefore, at that time the moon rises 1 h 17' later on the following evening : but when the moon is in the beginning of Aries, her orbit is so oblique to the hori zon, that 13 degrees of it rise in the short space of 17 minutes ; so that at that time the moon appears to rise for several successive nights at the same hour. Now, the moon is in the beginning of Aries once every month, and therefore she should appear to rise every month nearly at the same time for several nights. This is un doubtedly the case ; but as the moon is not full when this takes place, except in the harvest months, the phe nomenon passes unobserved. Since the moon is always opposite to the sun when she is full, and since it is only when she is in Pisces and Aries that the harvest moon can happen, the harvest moon can only take place when the sun is in the opposite signs, Virgo and Libra, that is in the autumnal months. Hence there can be only two full moons in the year which rise for almost a week to gether at the setting of the sun. The first of these moons is called the harvest, and the second the hunters'