What is the Difference Between True Meridian and Arbitrary Meridian?

The main difference between a true meridian and an arbitrary meridian lies in their definitions, purpose, and usage. Here are the key differences:

1. Definition: A true meridian is a reference direction that passes through the true north and south poles of the Earth, connecting the North Pole and the South Pole. An arbitrary meridian, on the other hand, is a convenient direction towards a well-defined permanent object, place, or area.
2. Purpose: True meridians are used to determine absolute directions and can be used for surveying both small and large areas. Arbitrary meridians are used to determine relative directions from the central line in a small area.
3. Fixity: True meridians are fixed and established by astronomical observations. Arbitrary meridians can vary with time and location, and they are defined by humans for their convenience.
4. Bearings: The horizontal angle between a true meridian and a line is known as true bearing. The horizontal angle between an arbitrary meridian and a line is known as arbitrary bearing.

In summary, true meridians are fixed and used for determining absolute directions, while arbitrary meridians are convenient reference directions used for determining relative directions in small areas.

Comparative Table: True Meridian vs Arbitrary Meridian

Here is a table comparing the differences between True Meridian and Arbitrary Meridian:

In summary, true meridians are fixed and established by astronomical observation, passing through the true north and south poles, while arbitrary meridians are convenient directions towards a well-defined permanent object, varying with time, location, and formed by humans for their convenience. True meridians are used to determine absolute directions, whereas arbitrary meridians are used to determine relative directions in small areas.