Page:Astronomy for Everybody.djvu/163

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VI

Eclipses of the Sun

If the moon moved exactly in the plane of the ecliptic she would pass over the face of the sun at every new moon. But, owing to the inclination of her orbit, as described in the preceding chapter, she will actually do so only when the direction of the sun happens to be near one of the moon's nodes. When this is the case we may see an eclipse of the sun if we are only on the right part of the earth.

Supposing the moon to pass over the sun, the first question is whether it can wholly hide the sun from our eyes. This depends not on the actual size of the two

Fig. 25.—The Shadow of the Moon Thrown on the Earth during a Total Eclipse of the Sun.

bodies but on their apparent size. We know that the sun has about four hundred times the diameter of the moon. But it is also four hundred times as far from us as the moon. The curious result of this Is that the two bodies appear of nearly the same size to our eyes. Sometimes

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