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Why is Greenwich, England, called the Prime Meridian?

Math and Traveling Read more from
Chapter Everyday Math

The reason for Greenwich, England, being the Prime Meridian is historical. An imaginary line passes through the old Royal Astronomical Observatory, which was chosen by astronomers of the day as zero longitude. The observatory is now a public museum located at the eastern edge of London. It is a great spot for tourists, who can find there a long strip of brass that stretches across the yard marking the “prime meridian.” Here it is possible to straddle the line with one foot in the Earth’s Eastern Hemisphere and the other in the Western Hemisphere.