. Astronomy for high schools and colleges . 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 equat
. Astronomy for high schools and colleges . 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 Fig. 9.—the right sphere. The sphere in this case is called a right sphere, becausethe diurnal motion is at right angles to the horizon. If nowthe observer travels southward from the equator, the southpole will become elevated above his horizon, and in thesouthern hemisphere appearances will be reproducedwhich we have already described for the northern, exceptthat the direction of the motion will, in one respect, bedifferent. The heavenly bodies will still rise in the eastand set in the west, but those near the equator will passnorth of the zenitli instead of south of it, as in our lati-tudes. The sun, instead of moving from left to right,there moves from right to left. The bounding line be-tween the two directions of motion is the equator, wherethe sun culminates north of the zenith from March tillSeptember, and south of it from September till March. If the observer travels west or east, the characterof the diurnal motion will not change. CIRCLES OF THE SPHERE. 23 § 6. CORRESPONDE
Size: 1669px × 1496px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, bookpublis, booksubjectastronomy
