What is the Difference Between True Meridian and Magnetic Meridian?

The true meridian and magnetic meridian are two different types of meridians used in geography and navigation. Here are the main differences between them:

• True Meridian: This is a great circle that passes through the true north and true south poles. It can be established by astronomical observations and represents the direction of the geographic north and south poles. True meridians are fixed and can be used for accurate navigation.
• Magnetic Meridian: This is an imaginary line connecting the magnetic south and north poles. It is parallel to the direction taken by a freely moving magnetized needle. Magnetic meridians vary with time and location, and they are not fixed like true meridians.

The angle between the true meridian and the magnetic meridian is known as the magnetic declination. A line having zero declination is called an agonic line, and lines with the same declination are known as isogonic lines.

In summary, true meridians are fixed and can be established by astronomical observations, while magnetic meridians vary with time and location and can be found using a freely moving magnetized needle. The magnetic declination is the angle between these two types of meridians.

Comparative Table: True Meridian vs Magnetic Meridian

The difference between True Meridian and Magnetic Meridian can be summarized in the following table:

True Meridian is established by astronomical observation and passes through true north and true south. In contrast, Magnetic Meridian is established using a freely moving magnetized needle and is influenced by the Earth's magnetic field. Magnetic Meridian varies with time and location, while True Meridian is fixed and stable. The angle between True Meridian and Magnetic Meridian is known as Magnetic Declination.