Page:Astronomy for Everybody.djvu/61

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THE SUN'S APPARENT PATH
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course gradually carries it once more to the equator, which it again crosses about September twentieth. Its course during the rest of the year is the counterpart of that during the first six months. It is farthest south of the equator on December twentieth, and again crosses it on March twentieth.

We see that there are four cardinal points in this apparent annual course of the sun. (1) Where we have commenced our watch is the vernal equinox. (2) The point where the sun, having reached its northern limit, begins to again approach the equator. This is called the summer solstice. (3) Opposite the vernal equinox is the

Fig. 8.—Apparent Motion of the Sun from March till September.

autumnal equinox, which the sun passes about September twentieth. (4) Opposite the summer solstice is the point where the sun is farthest south. This is called the winter solstice.

The hour circles which pass from one celestial pole to the other through these points at right angles to the equator are called colures. That which passes through

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