On November 1, the world celebrates Zero Meridian Day. The decision to establish it was made at a conference in Washington in 1884. Until that time, different countries had their own “zero meridians”, which greatly complicated navigation and map making.

At this conference, after the decision to recognize the Greenwich meridian as zero and to mark it on all maps, a proposal was made to calculate time around the world according to Greenwich. It was adopted together with the recommendation to calculate the day from 0.00 to 24.00 hours.

The prime meridian is believed to have been first introduced by Gerard Mercator in 1541 when he created his globe. But then this conditional line passed through one of the Canary Islands.

Unlike the equator, the prime meridian has no physical value. But questions about it were hotly discussed at international forums in 1875, 1881 and 1883.