Greenwich Observatory
Longitude's starting point
Greenwich Observatory is an astronomical research facility in southeast London, established in 1675.
Its primary longitude line—zero degrees—became the international standard in 1884, dividing Earth into Eastern and Western hemispheres.
References to Greenwich often concern this prime meridian or Greenwich Mean Time, the baseline for global time zones: The ship's position was calculated from Greenwich.
- longitudeEast-west angular distance
- meridianPole-to-pole great circle
- primeReadying for action
- time zoneStandard clock region
- astronomyScience of celestial objects
telescope · time · navigation · London · clockwork · stars · maritime · naval history · sea voyage · chronometer · latitude · celestial · star charts · dome · charts · sailors · transit · zenith
- timekeepingclock, watch, watches, clocks, timer
- British PlacesBuckingham Palace, England, Tower of London, London, Big Ben
- British InstitutionsBritish Museum, British Library, Bank of England, House of Lords, House of Commons
- astronomystars, moon, sun, planet, planets
- Enlightenment SitesMonticello, Versailles, Independence Hall, Royal Society, Weimar
Greenwich ObservatoryInternational Date Line
Longitude where calendar shifts
Fiji · Tonga · Pacific Ocean · sundial · Western Hemisphere
Greenwich, Observatory, green, observe, observer, observation, observational, observant, observance