. Astronomy for high schools and colleges . ss through. Thus, we speak of the meridianof Greenwich, or the meridian of Washington, meaningthereby that north and south semicircle on the earthssurface passing from one pole to the other through theRoyal Observatory, Greenwich, or through the KavalObservatory, Washington. DIURNAL MOTION IN DIFFERENT LATITUDES. ^1 § 5. THE DIURNAL MOTION IN DIFFERENT LATI-TUDES. As we have seen, the celestial horizon of an observerwill change its place on the celestial sphere as the observertravels from place to place on the surface of the he moves directl
. Astronomy for high schools and colleges . ss through. Thus, we speak of the meridianof Greenwich, or the meridian of Washington, meaningthereby that north and south semicircle on the earthssurface passing from one pole to the other through theRoyal Observatory, Greenwich, or through the KavalObservatory, Washington. DIURNAL MOTION IN DIFFERENT LATITUDES. ^1 § 5. THE DIURNAL MOTION IN DIFFERENT LATI-TUDES. As we have seen, the celestial horizon of an observerwill change its place on the celestial sphere as the observertravels from place to place on the surface of the he moves directly toward tlie north his zenith will ap-proach the north pole, but as the zenith is not a visiblepoint, the motion will be naturally attributed to the pole,which will seem to approach the point overhead. Thenew apparent position of tlie pole will change the aspectof the observers sky, as the higher the pole appears abovethe horizon the greater the circle of perpetual apparition,and therefore the greater the number of stars, whichnever Fig. 8.—the parallel sphere. If the observer is at the north pole his zenith and thepole itself will coincide : half of the stars only will be vis-ible, and these will never rise or set, but appear to movearound in circles parallel to the horizon. The horizonand equator will coincide. The meridian will be indeter-minate since Z and P coincide ; there \y\\\ be no east andwest line, and no direction but soutli. The sphere in thiscase is called a parallel sphere. 22 ASTRONOMY. If instead of travelling to tlie north the observer shouldgo toward the equator, the north pole would seem to ap-proach his horizon. When he reached the equator iDothpoles would be in the horizon, one north and tlie othersouth. All the stars in succession would then be visible,and each would be an equal time above and below thehorizon.
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