Meridian Longitude

The link between longitude and time is so fundamental that it literally divides our days. The world is divided into 24 primary time zones, each roughly 15° of longitude wide, corresponding to one hour of the Earth's rotation. The starting point is , which is effectively the mean solar time at the IERS Reference Meridian.

But what exactly is a meridian of longitude, and how did these lines become so critical to human civilization? What is a Meridian? meridian longitude

Because the Earth rotates 15° per hour, knowing your longitude requires knowing the exact time at a reference point (like Greenwich) and the local time on your ship. If your local noon (sun at its highest point) occurs 2 hours after noon in London, you are 30° west of London. The link between longitude and time is so