Meridian & Prime Meridian1.5 - Be able to use the major divisions of the Earth’s surface as astronomical reference points, including:
f) Prime Meridian
An imaginary line intersecting the Pole to the observer's zenith. It is a line of longitude. You are on a meridian between both poles right now.
This is an internationally agreed line of longitude stretching between the poles of the Earth and the Greenwich Observatory in London. From here all measurements of time are taken and is important when studing time zones.