The first stone of the Royal Observatory was laid at Greenwich near London by order of King Charles II. It is Greenwich where you can stand in two hemispheres at once today, laying one foot in the western hemisphere and the other in the eastern hemisphere. How did it happen that the small town, now part of Greater London, became the beginning of planetary coordinates? The story began with... bird droppings. In the mid – 1700 British Royal observatory was housed in the famous Tower of London, and the observations of royal astronomers strongly interfered with the local crows, they stained the telescopes. And then the eternal rivals of England – the French opened an observatory, and a great need for astronomical observations revealed. Charles II wrote in his decree: “In order to find the longitude of places, and to improve navigation and astronomy, we have decided to build an observatory within our park in Greenwich....”
Since the time of Charles II, ten royal astronomers, in full compliance with the monarch's decree, searched for longitude and improved navigation. Separately from them France, Italy and Sweden measured their longitude and time as well. Russia also had its own meridian – the Pulkovo meridian. When the meridian mess and confusion in time calculation began to hinder progress, an international conference was assembled in Washington. They spent a whole month deciding where to put the place, which would be the orientir of the whole world. Greenwich won: it happened thanks to its large telescope – the crosshairs in the middle of its eyepiece – that the imaginary north-south line, the famous Greenwich Zero Meridian, passed from north to south. In order to please tourists, the “imaginary line” was embodied in a copper rail. Today, the zero meridian does not pass through the observatory's telescope. The telescope moved from Greenwich to Hurstmonso because of the Greater London smog. And the meridian remained in its place, since the planetary origin of the coordinates must not be touched.