But the eclipses of most interest to us are those of the sun and moon, called respectively solar and lunar eclipses. In Fig. 33 the full moon, _M´_, is shown immersed in the shadow cast by the earth, and therefore eclipsed, and in the same figure the new moon, _M_, is shown as casting its shadow upon the earth and producing an eclipse of the sun. From a mere inspection of the figure we may learn that an eclipse of the sun can occur only at new moon--i. e., when the moon is on line between the earth and sun--and an eclipse of the moon can occur only at full moon. Why? Also, the eclipsed moon, _M´_, will present substantially the same appearance from every part of the earth where it is at all visible--the same from North America as from South America--but the eclipsed sun will present very different aspects from different parts of the earth. Thus, at _L_, within the moon's shadow, the sunlight will be entirely cut off, producing what is called a total eclipse. At points of the earth's surface near _J_ and _K_ there will be no interference whatever with the sunlight, and no eclipse, since the moon is quite off the line joining these regions to any part of the sun. At places between _J_ and _L_ or _K_ and _L_ the moon will cut off a part of the sun's light, but not all of it, and will produce what is called a partial eclipse, which, as seen from the northern parts of the earth, will be an eclipse of the lower (southern) part of the sun, and as seen from the southern hemisphere will be an eclipse of the northern part of the sun. [Illustration: FIG. 33.--Different kinds of eclipse.] The moon revolves around the earth in a plane, which, in the figure, we suppose to be perpendicular to the surface of the paper, and to pass through the sun along the line _M´ M_ produced. But it frequently happens that this plane is turned to one side of the sun, along some such line as _P Q_, and in this case the full moon would cut through the edge of the earth's shadow without being at any time wholly immersed in it, giving a partial eclipse of the moon, as is shown in the figure. In what parts of the earth would this eclipse be visible? What kinds of solar eclipse would be produced by the new moon at _Q_? In what parts of the earth would they be visible?