A meridian is a north – south line that has been selected as a zero point for astronomical observations. Astronomers use this line to compare thousands of observations and therefore creating an accurate map of the sky. The Prime Meridian was defined as the position of the large telescope in the Observatory. The cross-hairs on eyepiece on this ‘Transit Circle’ telescope are defined as 0º Longitude for the world.
The USA originally chose Greenwich as the base for its own time zone system and by 1884 over 70% of the world’s commerce was dependant on sea charts that used Greenwich as the Prime Meridian. Before this, most places kept to their own local time. There was nothing in place as to how time should be measured, when days began or ended or even how long an hour should be. As communication and commerce expanded there needed to be an international system that worked for everybody and Greenwich became the centre for world time now known as GMT or Greenwich Mean Time.
The line that you see on the floor at the top of Greenwich Park divides the eastern and western hemispheres of the Earth, the same way the equator divides the northern and southern hemispheres. Every place on Earth is measured in terms of its distance east or west of this line.
Tea talks, markets and more!
Check out where we'll be in the coming months.
Saturday October 21st | Beck Evans Farm Halloween event 9-2pm | Sidcup, DA14 5ET | |
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Sunday October 22nd | Beck Evans Farm Halloween event 9-2pm | Sidcup, DA14 5ET | |
Saturday October 28th | Royal Arsenal Farmers Market 10-3pm | Artillery Square, Royal Arsenal SE18 4DX | |
Sunday October 29th | Beck Evans Farm Halloween event 9-2pm | Sidcup, DA14 5ET | |
Sunday November 5th | Severndroog Producers Market 10-3pm | Shooters Hill, SE18 3RT | |
Saturday November 11th | Royal Arsenal Farmers Market 10-3pm | Artillery Square, Royal Arsenal SE18 4DX | |
Saturday November 18th | Mycenae House Christmas Fair, 10-4pm | Mycenae Road, SE3 7SE | |
Sunday November 19th | Mycenae House Christmas Fair, 10-4pm | Mycenae Road, SE3 7SE | |
Saturday November 25th | Royal Arsenal Farmers Market 10-3pm | Artillery Square, Royal Arsenal SE18 4DX | |
Sunday 26th November | Danson House Producers Market 10-3 | Danson Road, DA6 8HL | |
Saturday 2nd December | Royal Arsenal Christmas Market TBC | Artillery Square, Royal Arsenal SE18 4DX | |
Thursday 21st December | Royal Arsenal Christmas Market TBC | Artillery Square, Royal Arsenal SE18 4DX |