What is the meaning of GHA?

The term GHA stands for Greenwich Hour Angle, which is a key concept in celestial navigation. It describes the angular distance of an astronomical object measured westward along the celestial equator from the Greenwich meridian. This measurement is crucial for determining the position of celestial bodies in relation to Earth and is essential for accurate navigational calculations.

In celestial navigation, having the Greenwich Hour Angle helps mariners establish their longitude and assists in adjusting navigational instruments to account for the Earth's rotation. This concept is fundamental because it allows navigators to convert between different time zones and universal time, providing clarity on the position of celestial objects relative to the observer's position on Earth.

The other options, while they may contain similar terms, do not accurately represent what GHA stands for in the context of navigation. Understanding GHA as the Greenwich Hour Angle is essential for effective navigation and seamanship practices.