Lectures on astronomical theories . rily educated, in a very short time. Parallax may be defined as—the alteration in theapparent locality of an object caused by the actual alter-ation in the point of view of an observer. Or, in otherwords, parallax is the alteration in the visual angle atwhich an object is seen in consequence of movement bythe observer from one place to another place. Let threeobjects marked 1, 2, 3 respectively be in a line from theplace A. of an observer and at such difterent distancesirom the flat surface of the wall W. W., that the object PARALLAX. numbered 1, is almost c
Lectures on astronomical theories . rily educated, in a very short time. Parallax may be defined as—the alteration in theapparent locality of an object caused by the actual alter-ation in the point of view of an observer. Or, in otherwords, parallax is the alteration in the visual angle atwhich an object is seen in consequence of movement bythe observer from one place to another place. Let threeobjects marked 1, 2, 3 respectively be in a line from theplace A. of an observer and at such difterent distancesirom the flat surface of the wall W. W., that the object PARALLAX. numbered 1, is almost close to the wall; No. 2, is consid-erably further from the wall than No. 1 ; and No. 3, isyet further from the wall than No. 2. Now if the ob-server move from his station at A. to a station at B,considerably to the left of A., the effect will be that a linefrom his eye through the object No. 2, if continued to thewall, will strike the wall at the place marked No. 2thereon; and a line from his eye through the object No. 3, Fig. vdll strike the wall at the place, marked No. 3, stillfurther to the right: whilst a line from his eye to thefirst object which is almost close to the wall, will strikethe wall only a very short distance to the right. Nowif the observer return past his first central ^tion at A.,and move to C, a place as far distant to the right of B. was to the left of A., then, lines, drawn from his eyethrough the objects 2 and 3 respectively, will strike thewall to the left of the central line as shown in the entire distance to which each object suffers suchapparent displacement being proportional to the distanceof the observers station from the central station, and tothe distance of the object from the wall. This apparent PARALLAX. 9 angular displacement of the object in consequence ofalteration in the observers station, is called parallax ofthe object. Fig. 2.—Let represent the diameter of the earthsorbit; and m. and n. two stars at diffe
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Keywords: ., bookcentury18, bookdecade1870, booksubjectastronomy, bookyear1876
