由于地球是一个近似球体，经线之间的距离并非均匀的，这一点与纬线不同。
Let’s clear up a few frequent myths:
The solution lies in time. Because the Earth rotates 360° in 24 hours, it turns 15° every hour. Therefore, if you can compare the local time at your current position (determined by the sun's highest point at noon) with the time at a known reference meridian (like Greenwich), the difference directly reveals your longitude. If your local noon is four hours earlier than in Greenwich, you are 4 hours × 15° per hour = 60° east. meridian longitude
Greenwich Mean Time (GMT), based on the Prime Meridian, was long used as the international time standard. Today, it has been succeeded by Coordinated Universal Time (UTC), which is kept precise by atomic clocks but remains anchored to the Prime Meridian grid. The International Date Line
Directly opposite the Prime Meridian (0°) is the 180° meridian. This line, located mostly in the Pacific Ocean, acts as the . When you cross this line moving west, you gain a day; moving east, you lose a day. 3. Spatial Reference (GIS) If your local noon is four hours earlier
Coordinates are marked as E (East) or W (West). For example, New York City sits at approximately 74° W, while Tokyo is at roughly 139° E. The Connection Between Longitude and Time
要理解子午线经度的真正力量，我们需要回到那个被称为“经度难题”的世纪大挑战时代。 The International Date Line Directly opposite the Prime
between two points using their longitude/latitude.
