Meridian | Longitude

Without knowing their meridian longitude, sailors frequently got lost, miscalculated voyages, and crashed into coastlines. In 1707, the Scilly naval disaster resulted in the loss of four British warships and over 1,400 sailors due to a navigational error.

Urban planners, environmental scientists, and logistics companies utilize GIS software to overlay data onto geographical coordinates. Whether tracking climate change patterns or optimizing delivery truck routes, meridian longitude serves as a primary anchor for spatial data.

Measuring is mathematically elegant. A full circle of the Earth is 360°. Because the Earth rotates once every 24 hours, we get a perfect correlation: 360° / 24 hours = 15° per hour. meridian longitude

| Meridian | Longitude | Significance | |----------|-----------|---------------| | | 0° | Passes through Greenwich, London. Reference for all longitudes. | | Anti-Meridian | 180° | Opposite the Prime Meridian; largely follows the International Date Line. | | Tropic Meridians | Various | Used in celestial navigation and climate zones. |

Before Greenwich became standard, many countries used their own prime meridians. The (2°20′14″E) was used on French maps for centuries. It is famously referenced in Dan Brown’s novel The Da Vinci Code as the “Rose Line.” Because the Earth rotates once every 24 hours,

Before railroads, every town set its clocks to its own local meridian solar noon. When it was noon in New York, it was 11:48 AM in Washington, D.C. The expansion of rapid train travel made this localized system dangerous, causing train schedule confusion and head-on rail collisions.

Because the Earth spins on an axis, the North and South Poles provide natural, fixed starting points for latitude. The equator sits exactly halfway between them. Longitude, however, has no such natural anchor. Because the Earth rotates horizontally, any vertical line could theoretically serve as the starting point (0° longitude). Egypt / New Orleans

Distance=111.32×cos(latitude)Distance equals 111.32 cross cosine open paren latitude close paren Location Example Distance of 1° of Longitude Quito, Ecuador (Equator) 111.3 km (69.1 miles) 30° N/S Cairo, Egypt / New Orleans, USA 96.4 km (59.9 miles) 45° N/S Bordeaux, France / Minneapolis, USA 78.8 km (48.9 miles) 60° N/S Oslo, Norway / St. Petersburg, Russia 55.8 km (34.7 miles) 90° N/S North & South Poles 0 km (0 miles)

Understanding meridians, longitude, and their primary reference point—the Prime Meridian—is crucial for everything from using GPS to setting your watch. What is a Meridian?

: The Prime Meridian and the International Date Line together divide the Earth into the Eastern Hemisphere and the Western Hemisphere.