The case of the wandering Prime MeridianOct 022015
Many geography fans would consider the Prime Meridian an absolute must in terms of places to visit. And the Royal Observatory in Greenwich, England is likely to be the point on the Meridian that comes to most people's minds. We've been there a couple of times and have always patiently stood in line to place one foot on both sides of the famous east/west dividing line. Then taken the pictures to prove it. Imagine our surprise to learn that the real meridian is about 333 feet east, marked unceremoniously by a litter can!
As most of our readers will know, any place on the earth can be referenced by its position on imaginary lines going north/south (latitude) and east/west (longitude). A line of longitude is called a meridian. Unlike latitude, where 0 degrees (the equator) is fixed by a natural definition (the axis of the earth's rotation), 0 degrees longitude is arbitrary. It could have been placed on any east/west point. Greenwich was established as the Prime Meridian of the world in 1884 - essentially by a vote (22 - 1 with 1 absention).
As Jacobs describes, the problem with the placement was grounded on a mis-measurement at the time that wasn't discovered until GPS technology arrived more than a century later. So, if you do go to the Royal Observatory (it's definitely fun), be sure and get that picture astride two hemispheres near that litter bin.