Astronomy for amateurs . name equator is given to a great circle situatedbetween the two poles, at equal distance, which divides 225 ASTRONOMY FOR AMATEURS the globe into two hemispheres. The equator isdivided into 360 parts or degrees, by other circles thatgo from one pole to the other. These are the longitudesor meridians (see Fig. 62). The distance between theequator and the pole is divided into larger or smallercircles, which have received the name of latitudes. 90 degrees are reck-oned on the one sideand the other of theequator, in the di-rection of the Northand South poles,respectively.
Astronomy for amateurs . name equator is given to a great circle situatedbetween the two poles, at equal distance, which divides 225 ASTRONOMY FOR AMATEURS the globe into two hemispheres. The equator isdivided into 360 parts or degrees, by other circles thatgo from one pole to the other. These are the longitudesor meridians (see Fig. 62). The distance between theequator and the pole is divided into larger or smallercircles, which have received the name of latitudes. 90 degrees are reck-oned on the one sideand the other of theequator, in the di-rection of the Northand South poles,respectively. Thelongitudes are reck-oned from somepoint either to Eastor West: the lati-tudes are reckonedNorth and South,from the going from East to West, or inversely, the longitudechanges, but in passing from north to South of anyspot, it is the latitude that alters. The circles of latitude are smaller in proportion asone approaches the poles. The circumference of theworld is 40,076,600 meters at the equator. At the 226. Fig. 62.—The divisions of the and latitudes. THE EARTH latitude of Paris (48^ 50) it is only 26,431,900 point situated at the equator has more ground totravel over in order to accomplish its rotation in tv^enty-four hours than a point nearer the pole. We have already stated that this velocity of rotationis 465 meters per second at the equator. At the latitudeof Paris it is not more than 305 meters. At the polesit is nil. The longitudes, or meridians, are great circles ofequal length, dividing the Earth into quarters, like theparts of an orange or a melon. These circumvent theglobe, and measure some 40,000,000 (40,008,032) may remember in passing that the length of themeter has been determined as, by definition, the ten-millionth part of the quarter of a celestial meridian. Thus, w^hile rotating upon itself, the Earth spinsround the Sun, along a vast orbit traced at 149,000,000kilometers (93,000,000 miles) from the central
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectastronomy, bookyear19
