Question

Which one of the following methods is used to measure distance of a planet or a star from earth?
A. Echo method
B. Parallax method
C. Triangulation method
D. None of these

Answer 1

Hint: The distance between earth and other stars and planet is too large to be measured by conventional methods. In order to measure such a large distance, we use a method which relies on the position of far away objects and the light coming from those stars or planets.

Complete step-by-step answer:
The method that is used for measuring distance of a planet or a star from earth is known as the method of parallax. This method works on the principle that the position of a planet or a star changes when viewed from different positions.
For example, consider that you are trying to view an object placed in front of you. Cover your left eye and view the object from your right eye. It will be at a certain position. When you switch your eye to view the object, it will seem to have shifted from the position from which you viewed it with the other eye. The actual position of the object does not change but viewing it from two different positions which are your left and right eye causes this shift in position of the object for the viewer.
In the parallax method to measure distances of earth from stars and planets, we measure the position of a star or planet from one position and then from another position. The amount of shift produced in the position of the star or planet is used to calculate the distance from that star or planet.
Hence, the correct answer is option B.

So, the correct answer is “Option B”.

Additional Information: The accuracy of this method increases if the distance between the two points of observation increases.

Note: The echo method makes use of a sound wave to measure distance. The sound waves do not travel fast enough to be utilized in measuring distances from stars and planets. Similarly, triangulation method is suitable for use on ground and not for measuring interplanetary distances.