This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1868 Excerpt: ... are both on the opposite side of the sun from the earth, than when Venus is on the opposite side and Jupiter on the same side as the earth. This shows that the planet Jupiter has also considerable influence on the spots. ECLIPSES. 85. Eclipses of the Sun and Moon.--The earth and the moon are both opaque spheres, and ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1868 Excerpt: ... are both on the opposite side of the sun from the earth, than when Venus is on the opposite side and Jupiter on the same side as the earth. This shows that the planet Jupiter has also considerable influence on the spots. ECLIPSES. 85. Eclipses of the Sun and Moon.--The earth and the moon are both opaque spheres, and they must therefore cast shadows in a direction away from the sun. Since the sun is much larger than these bodies, their shadows must be conical, as shown in Figure 44. The figure shows also that the shadow consists of two parts. The darkest part is called the umbra, and in this the sunlight is wholly cut off. The lighter part is called the penumbra, and in this only a part of the sunlight is cut off. The moon and the earth in their movements carry with them their cones of umbra and penumbra; and it is by throwing these total or partial shadows upon each other that they produce the phenomena of eclipses. On examining Figure 44, it will be seen at once that an eclipse of the sun can happen only at the time of new moon, and an eclipse of the moon only at full moon. In all other positions of the moon, her cone of shade is projected into space away from the earth, and the terrestrial cone of shade does not meet the moon. It does not follow, however, that there is an eclipse of the sun at every new moon, or of the moon at every full moon. This would be true if the orbits of the earth round the sun, and of the moon round the earth, were in the same plane. Then at each opposition or conjunction the centres of the three bodies would necessarily lie in a straight line. But the orbit of the moon is inclined to the ecliptic at an angle of about 50; so that it often happens at the time of new moon that our satellite throws its shadow above or below the ear...
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Seller's Description:
Very Good+ First Edition. Hardcover. W.J. Rolfe and J.A. Gillet, teachers in the high school, Cambridge, Mass. General astronomy book for all education levels. Color spectrum frontispiece. Light shelf/edge wear, loss at head and tail, rear board cracked and repaired, very minor foxing at preliminaries, else tight, bright, and unmarred. Bound in black cloth with a black leather spine, color frontispiece. Small 8vo. 224pp plus 17 plates at rear with various constellations on a black field. Illus. (color and b/w plates). Appendix. Questions for students. Index.
