![]() To chart your position there are two co-ordinates you need: This meant that ships could miss their supply points, sail past safe harbours or, worse, become wrecked upon rocks or reefs they didn’t realise they were sailing into. Voyages could last for months and it was easy to lose track of your east–west position at sea. Sailing the seas was a dangerous business. Until the invention of an accurate sea clock by carpenter and clockmaker John Harrison in the 18th century, there was no dependable technique to measure a ship’s longitude – its east or west position at sea – especially when the ship’s navigator could not sight landmarks or celestial markers due to the weather. Image: ANMM.įor as long as humans have been exploring, we have sought reliable methods to navigate our way across the Earth. See if you can find out what your latitude and longitude are by using a globe.‘Ships, Clocks & Stars: The Quest for Longitude’ traces the history of finding reliable methods for determining your longitude at sea. If I want to see where a place is in the world, I just need to look at where the lines cross, and read the numbers.Īh, there he is! Latitude is 32 degrees south, and longitude is 115 degrees east. The other lines show how many degrees east or west of this you are. The line going through London, called Greenwich Meridian, is the starting point at zero degrees. Lines of longitude run from the top of the Earth to the bottom, and divide up the Earth a bit like the segments of an orange. Lines of latitude run around the Earth like imaginary hoops and have numbers to show how many degrees north or south they are from the Equator. To do that, I’ll use what’s called latitude and longitude. Well I’m on the half that’s above the Equator, which is called the Northern Hemisphere and he lives on the half that’s below the Equator, which is the Southern Hemisphere.īut I also need to find out how far around the Earth he is, and how far down. Running around the middle of the planet is an imaginary line called the Equator. It’s not a problem though, because I know a good way to find out exactly where he lives.įirst, I’m going to find out which half of the Earth he’s on. ![]() ![]() I’ve been asked to deliver this parcel to my cousin but he lives on an island and doesn’t have an address to send things to, like you or me. ![]()
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