The exception of the "circumpolar" stars
In twenty-four hours the whole dome of heaven, including the moon, sun, and fixed stars, rotates about an axis which joins the observer to the celestial pole, whose position is approximately marked by the Pole Star. With the exception of the "circumpolar" stars, which are too near the pole to dip under the horizon, the heavenly bodies all appear to rise upwards from the eastern boundary and to sink below the western boundary of the horizon plane. In this motion, called the apparent diurnal motion of the celestial sphere, the fixed stars retain the same position relative to one another, so that at any place the time between the risings or settings of any two stars and the direction in which any star is seen rising or setting are always the same. Relative to the rising of any fixed star, the moon and the sun each rise a little later on successive days. They thus seem to be slipping backwards below the eastern margin of the horizon plane. The sun takes 365 1/4 days to retreat eastwards till it is again in the same position relative to a fixed star, i.e. it slips under the horizon plane eastwards through approximately one degree per day. The moon takes 27 1/3 days to do so, but, as the sun is slipping back, though more slowly, in the same direction it takes a little longer, namely, 29 1/2 day to return to the same position relative to the sun. In the figure new moon would occur about January 7th and the next new moon about February 5th. At last quarter the moon is 90° west of the sun, rising about midnight and reaching its highest point in the heavens about 6 A.M., when its easterly half is visible. At first quarter it sets about midnight, reaching its highest point in the heavens (meridian transit) at about 6 P.M., when its westerly face is illumined.
zaman: 4:23 AM