Mark Henderson answered
Greenwich, England
Longitude: 0* 0' 0"
Latitude: 51* 28' 38"N (North of the Equator)
Greenwich Mean Time
Greenwich in London is the place where West meets East along the Greenwich Meridian Line at the Royal Observatory Greenwich. This is the place where all the world's time zones are calculated from - which explains why Greenwich has a longitude of 0* 0' 0". Greenwich Mean Time is the world's absolute time reference, which never changes with the seasons.
Places
Greenwich is also important in defining where something is located in the world. Every place has a latitude (their distance North or South from the Equator) and a longitude (their distance West or East from the Greenwich Meridian). The Greenwich Meridian makes it possible for any place in the world to be plotted exactly using latitude and longitude co-ordinates - the Equator has a latitude of 0* 0' 0" and the Greenwich meridian has a longitude of 0* 0' 0".
History
The equator is the line of longest distance around the planet and therefore was a natural starting point for calculating latitude. However, with longitude there is no natural starting line, and therefore one had to be invented.
Each country's maps had their own Prime Meridians, normally passing through a capital or important city, so to standardise these maps, one Meridian had to be agreed on throughout the world. In 1884, the International Meridian Conference decided to adopt the Greenwich Meridian as the zero point of longitude.
Other Prime Meridians before the adoption of Greenwich, England
Longitude: 0* 0' 0"
Latitude: 51* 28' 38"N (North of the Equator)
Greenwich Mean Time
Greenwich in London is the place where West meets East along the Greenwich Meridian Line at the Royal Observatory Greenwich. This is the place where all the world's time zones are calculated from - which explains why Greenwich has a longitude of 0* 0' 0". Greenwich Mean Time is the world's absolute time reference, which never changes with the seasons.
Places
Greenwich is also important in defining where something is located in the world. Every place has a latitude (their distance North or South from the Equator) and a longitude (their distance West or East from the Greenwich Meridian). The Greenwich Meridian makes it possible for any place in the world to be plotted exactly using latitude and longitude co-ordinates - the Equator has a latitude of 0* 0' 0" and the Greenwich meridian has a longitude of 0* 0' 0".
History
The equator is the line of longest distance around the planet and therefore was a natural starting point for calculating latitude. However, with longitude there is no natural starting line, and therefore one had to be invented.
Each country's maps had their own Prime Meridians, normally passing through a capital or important city, so to standardise these maps, one Meridian had to be agreed on throughout the world. In 1884, the International Meridian Conference decided to adopt the Greenwich Meridian as the zero point of longitude.
Other Prime Meridians before the adoption of Greenwich, England
- El Hierro
- Rome
- Copenhagen
- Jerusalem
- Saint Petersburg
- Pisa
- Paris
- Philadelphia
- Washington