Astronomy for the use of schools and academies (1882) (14763841842)

Identifier: astronomyforuseo00gill (find matches)

Title: Astronomy for the use of schools and academies

Year: 1882 (1880s)

Authors: Gillet, J. A. (Joseph Anthony), 1837-1908 Rolfe, W. J. (William James), 1827-1910

Subjects: Astronomy

Publisher: New York : Potter, Ainsworth, & Co.

Contributing Library: The Library of Congress

Digitizing Sponsor: The Library of Congress

Text Appearing Before Image:

half of the whiteportion comes into view, the terminator begins to appear asa convex line, and this line becomes more and more convextill the whole of the white half comes into view, when theterminator becomes circular. The moon is of itself a dark, opaque globe ; but the halfthat is towards the sun is always bright, as shown in Fig. 112.This bright half of the moon corresponds to the white halfof the globe in the preceding illustration. As the moonrevolves around the earth, different portions of this illuminedhalf are turned towards the earth. At new moon, when themoon is in conjunction, the bright half is turned entirelyaway from the earth,, and the disc of the moon is black and 96 ASTRONOMY. invisible. Between new moon and first quarter, less thanhalf of the illumined side is turned towards the earth, andwe see this illumined portion projected as a crescent. Atfirst quarter, just half of the illumined side is turned towardsthe earth, and we see this half projected as a half-circle.

Text Appearing After Image:

Between first quarter and full, more than half of the illu-mined side is turned towards the earth, and we see it asgibbous. At full, the whole of the illumined side is turnedtowards us, and we see it as a full circle. From full to newmoon again, the phases occur in the reverse order. ASTRONOMY. 97 99. The For??i of the Mo oils Orbit.—The orbit of themoon around the earth is an ellipse of slight eccentricity.The form of this ellipse is shown in Fig. 113. C is thecentre of the ellipse, and E the position of the earth at oneof its foci. The eccentricity of the ellipse is only aboutone-eighteenth. It is impossible for the eye to distinguishsuch an ellipse from a circle. 100. The Inclination of the Moons Orbit. — The plane

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1882

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