The Prime Meridian isn’t Where You Think it is

Elizabeth Borneman

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The Greenwich Prime Meridian, long considered to be the baseline for the measurement of time zones around the world, has now been discovered to not be the most accurate. Although the Greenwich location was determined to be the spot for the Prime Meridian in 1884, modern geographers and navigators have actually found that the area of zero longitude is elsewhere.

The Prime Meridian divides the world into the eastern and western hemispheres. Image: NASA, public domain.
The Prime Meridian divides the world into the eastern and western hemispheres. Image: NASA, public domain.

The true Prime Meridian is located about 334 feet east of the current Airy Transit Circle at the Royal Observatory in Greenwich, England. GPS and other modern technologies have been used to reexamine the location of zero longitude, which can account for the 334 foot difference. The traditional use of telescopes was how the original meridian was placed.

The Airy meridian marked as the “Prime Meridian of the World” (dotted line), and the modern reference meridian indicating zero longitude using GPS (solid line). (Imagery © 2014 Google Maps, Infoterra Ltd. & Bluesky)
The Airy meridian marked as the “Prime Meridian of the World” (dotted line), and the modern reference meridian indicating zero longitude using GPS (solid line). (Imagery © 2014 Google Maps, Infoterra Ltd. & Bluesky)

Researchers have determined that the difference in the location of the Prime Meridian can be linked to a difference in the measuring of the earth’s rotation, by astronomical or geodetic coordinates. GPS can measure the true location of things like the meridian, cutting through details like differentiating gravitational pulls on parts of the Earth because of geography.

There are many technologies that modern geographers and navigators can use to perfect measurements taken long ago. While the Greenwich Prime Meridian has been the standard for many, many years, maybe it is time that modern science took over.

The Research

Malys, S., Seago, J. H., Pavlis, N. K., Seidelmann, P. K., & Kaplan, G. H. (2015). Why the Greenwich meridian movedJournal of Geodesy, 1-10.

Researchers Explain Why the Greenwich Prime Meridian Moved – University of Virginia

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About the author
Elizabeth Borneman
My name is Elizabeth Borneman and I am a freelance writer, reader, and coffee drinker. I live on a small island in Alaska, which gives me plenty of time to fish, hike, kayak, and be inspired by nature. I enjoy writing about the natural world and find lots of ways to flex my creative muscles on the beach, in the forest, or down at the local coffee shop.