The prime meridian passes through the United Kingdom, France, Spain, Algeria, Mali, Burkina Faso, Ghana and Togo. The prime meridian represents the longitude of 0 degrees.
The prime meridian was established as 0 degrees longitude in 1884 at an international conference. Prior to 1884, countries established their own local starting locations for longitude, but the increase of international commerce led to the need for a standardized prime meridian. The United Kingdom and its former colonies set the Royal Observatory at Greenwich, located outside of downtown London, as the starting location for longitude in 1675. Greenwich was selected as the prime meridian by the majority of 41 delegates at the international conference in Washington, D.C. However, the United Kingdom and the United States were already using Greenwich as the starting point before the official designation.
The prime meridian divides the eastern and western hemispheres, while the equator is the line that divides the northern and southern hemispheres and has a latitude of 0 degrees. The equator is close to 25,000 miles long. It passes through Sao Tome and Principe, Gabon, the Republic of the Congo, the Democratic Republic of the Congo, Uganda, Kenya, Somalia, Maldives, Indonesia, Kiribati, Ecuador, Colombia and Brazil. Locations along the equator have a warm climate year round, with an average day temperature around 86 degrees Fahrenheit and an average night temperature of 73 degrees Fahrenheit.