Meridian Longitude Hot! -

在精确描述“子午线”之前，我们有必要先厘清“经度”与“纬度”这对兄弟之间的区别与联系。（Latitude）是由赤道平面量度的一条南北向的线，像梯子的横档一样平行环绕地球。而 经度 （Longitude）则是一个系统，用以测量地球上某一点东西方向的位置，它由一系列假设的、连接南北极的半圆形“子午线”构成。

: While often used interchangeably, "longitude" refers to the specific angular measurement (in degrees), whereas "meridian" refers to the physical line on a map or globe that connects all points with that same longitude. Prime Meridian : The starting point for measuring longitude is the Prime Meridian (0°) , which passes through Greenwich, England The Hemispheres meridian longitude

Every system of measurement needs a zero point. For meridian longitude, that zero point is the . Historically, different civilizations used various reference meridians—for example, the Romans used the meridian through the Canary Islands, while Arab astronomers used a meridian through the western edge of the known world. which passes through Greenwich