Where is the starting point for measuring longitude?

Answer 1

The Prime Meridian, or the Greenwich meridian. It is defined as the meridian that passes through the optical axis of the transit telescope in the Royal Observatory at Greenwich, England.

Answer 2

For a long time, Keith P's answer was correct.

However, with GPS, a new "zero longitude" was selected.

There is a bit of an explanation at the source, below. In summary, the new geocentric frame provides a better fit for the mean sea level.

There may be a difference of 100 m between the "old" (pre-1984) Greenwich meridian, the one at the telescope, and the new zero longitude.

PS: The zero is not based on an actual feature on Earth.

Answer 3

The previous answer was correct, but to make it much simpler think of a t. Lattitude measures width and Longitude measures length. Both meet at 0 degrees. Find where 0 degrees for lattitude and longitude and you have your answer.

Answer 4

Greenwhich is the starting point of measuring longitude,this is zero point which pass some cities in the world like Accra Ghana in Africa and London UK