Chapter 17, Problem 1Q

To determine

The method in which the distance measurement of star is similar to human binocular vision.

Explanation of Solution

Consider an object at point A. Observe it from points B and C some distance apart. The position of Object at A appears different from two points.

This apparent change in position of the object due to change in point of the observer is called parallax. The parallax is also the angle opposite to baseline that lines AC and BC make with the line AD. Binocular vision is the method of measuring distance by naked eye.

To measure the distance of any astronomical object requires a very large baseline and highly precise angular measurements. Due to revolution of Earth around Sun, the direction of a nearby stars changes from Earth.Nearby stars appear to move back and forth relative to more distant stars and the motion knownas stellar parallax.

Relation between a star’s distance and its parallax:

$d=\frac{1}{p}$

Here, $d$ is thedistance to a star, in parsecs and $p$ is the parallax angle of that star, in arc second.

The parallax of a star is half of the angle through which star shift.The larger the parallax p, the smaller is the distance d to the star.