. Astronomy for students and general readers . The angle betweenthese lines represents the apparent diameter of the moonas seen from the earth. Continuing them to the sun, theyshow the apparent diameter of the moon as projected uponthe sun. It will be seen that in the case supposed, when * It will be noted that all the figures of eclipses are necessarily drawnvery much out of proportion. Really the sun is 400 times the distanceof the moon, which again is 60 times the radius of the earth. But itwould he entirely impossible to draw a figure of this proportion ; weare therefore obliged to represe
. Astronomy for students and general readers . The angle betweenthese lines represents the apparent diameter of the moonas seen from the earth. Continuing them to the sun, theyshow the apparent diameter of the moon as projected uponthe sun. It will be seen that in the case supposed, when * It will be noted that all the figures of eclipses are necessarily drawnvery much out of proportion. Really the sun is 400 times the distanceof the moon, which again is 60 times the radius of the earth. But itwould he entirely impossible to draw a figure of this proportion ; weare therefore obliged to represent the earth as larger than the sun, andthe moon as nearly half way between the earth and sun. MCLIPSES OF THE SUN. 175 the vertex of the shadow is between the earth and moon,the latter will necessarily appear smaller than the sun, andthe observer will see a portion of the solar disk on allsides of the moon, as shown in Fig. 62. If the moon were a little nearer the earth than it is rep-resented in the figure, its shadow would reach the earth. Fig. 62.—^dakk body op moon projected on sttn during eclipse. in the neighborhood of 0. We should then have a totaleclipse at each point of the earth on which it fell. It willbe seen, however, that a total or annular eclipse of the sunis visible only on a very small portion of the earths sur-face, because the distance of the moon changes so littlethat the earth can never be far from the vertex T^of theshadow. As the moon moves around the earth from westto east, its shadow, whether the eclipse be total or annu-lar, moves in the same direction. The diameter of theshadow at the surface of the earth ranges from zero to 150miles. It therefore sweeps along a belt of the earths sur-face of that breadth, in the same direction in which theearth is rotating. The velocity of the moon relative tothe earth being 3400 kilometres per hour, the shadowwould pass along with this velocity if the earth did not ro-tate, but owing to the earths rot
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