Ask a Teacher

concept of parallax method with a problem

Parallax Method
       To measure the distance r of a far away object S by parallax method we look at it from two positions A and B separated by a distance x. If ? radians is the angle between the two directions, then

                ? = x / r       ?r = x / ?

Parallax angle of a heavenly body measured from two points diametrically opposite on the equator of the earth is 1.0 minute. If the radius of the earth is 6400 km, find the distance of the heavenly body from the earth.

             x = 6400 × 2 km;  r = ?;   ? = 1' = radian;
          x / r = ?;       ?r = x / ? = 6400 × 2 × 60 180 /? = 4.4 ×10⁷ km