A few fundamental rules can be easily acquired, however, and these will enable us to locate the moon in the right quarter of the heavens at any time of the day or night when we know its phase and the approximate position of the sun at the same instant, and thus we may avoid some of the most obvious blunders that are made in dealing with the general aspect of the moon at any given time. As can be verified by direct observation, the moon is always moving continually eastward. Since it makes a complete revolution around the earth from new moon back to new moon again in a little less than thirty days, it passes over about twelve degrees a day (360° divided by 30), on the average, or one-half a degree an hour, which is about the angular extent of its own diameter. Therefore every hour the moon moves eastward a distance equal to its own diameter. This is of course only approximate as the moon moves more rapidly in some parts of its orbit than in others. In addition to its real eastward motion the moon shares the apparent daily westward motion of all celestial objects which is due to the daily rotation of the earth on its axis in the opposite direction. That is, the moon, as well as the sun, stars and planets, rises in the east and sets in the west daily. On account of its continuous eastward motion, however, the moon rises later every night, on the average about fifty minutes, though the amount of this daily retardation of moon-rise varies from less than half an hour to considerably over an hour at different seasons of the year and in different latitudes. In the course of a month then the moon has risen at all hours of the day and night and set at all hours of the day and night. It might seem unnecessary to emphasize the fact that the moon always rises in the east were it not that the astronomer occasionally meets the man who insists that he has at times seen the moon rise in the west. To be sure the new crescent moon first becomes visible above the western horizon shortly after sunset though it rises in the east the morning of the same day shortly after sunrise. As is also true of the sun the exact point on the horizon where the moon rises or sets varies from day to day and from season to season. In one month the moon passes over very nearly the same path through the heavens that the sun does in one year, for the moon's path is inclined only five degrees to the ecliptic or apparent path of the sun through the heavens. It can never pass more than 28-1/2° (23-1/2° + 5°) south of the celestial equator, nor more than 28-1/2° north of it. It has a slightly greater range in altitude than the sun, therefore. North of 28-1/2° north latitude it always crosses the meridian south of the zenith and below 28-1/2° south latitude it crosses the meridian north of the zenith. In tropical regions the moon sometimes passes north of the zenith, sometimes south, or again directly through the zenith.