alfaiop.blogg.se - Coordinates of sydney opera house

In the Northern Hemisphere, European sailors by the 17th and 18th centuries used cross-staffs to measure the angle of the North Star.

For example the further you are from the equator, lower the Sun will be appear on the horizon. Latitude has long been comparatively easy to establish by measuring the height of objects in the sky from the horizon. Yep – this is how the GPS on your phone can locate you on a map (GPS being the acronym for ‘Global Positioning System’). So the earth is measured with an invisible grid? Terrella is a small, magnetised globe with the lines of longitude and latitude engraved on both the globe and the outer case. The Sydney Opera House’s latitude and longitude are given as 33° 51′ 30″ S, 151° 12’ 53” E – meaning it lies 33 degrees, 51 minutes and 30 seconds south of the equator and 151 degrees, 12 minutes and 53 seconds east of Greenwich. There are 60 minutes in a degree and 60 seconds in a minute (similar to measuring time). Latitude and longitude are divided in degrees (°), minutes (‘) and seconds (“). Handy tip: when giving a co-ordinate, latitude (north or south) always precedes longitude (east or west). Greenwich is the prime meridian and corresponds to 0°, while the International Date Line is where east and west meet again, at 180°.

They represent the distance east or west from Greenwich in London, England.

Longitude – Lines of longitude, called meridians, run vertically from pole to pole.

Each degree of latitude corresponds with 60 nautical miles, or 111.1 kilometres, on the Earth’s surface. The equator represents 0° and each pole represents 90°.

Latitude – Lines of latitude run in horizontal parallels and represent distance north or south from the equator, measured in an angle from the centre of the Earth.

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.

‘Ships, Clocks & Stars: The Quest for Longitude’ traces the history of finding reliable methods for determining your longitude at sea.