noun

• A planet's meridian adopted as the zero of longitude.

  ‘That's the instant the sun is aligned with the degree line of longitude, or the prime meridian - also called the Greenwich Meridian.’

  More example sentences

  • ‘Zero degrees longitude, the prime meridian could be anywhere - and has been, from the designated home ports of Rome to Paris to Jerusalem to Philadelphia to St. Petersburg.’
  • ‘On the earliest charts displaying a longitude scale, the prime meridian passed through the Canaries.’
  • ‘The prime meridian is the line which runs through Greenwich Observatory and is used globally as a standard ‘zero’ point.’
  • ‘And it's where time itself starts, being the site of the prime meridian, Greenwich Mean Time or degrees longitude, depending on what you prefer.’
  • ‘This forthcoming transit is centered on about 08: 20, Universal Time (UT: the standard time for the prime meridian passing through the Greenwich Observatory in London, England).’
  • ‘In this sense London marked the prime meridian in a cultural cartography too - a global chronocultural geography.’
  • ‘Because of Britain's sustained support for achievements in astronomical and navigational measurement, the Royal Observatory Greenwich landed the prime meridian.’
  • ‘The first prime meridian was established by Hipparchus of Rhodes in the 2nd century BC.’
  • ‘Only on the fine line of the prime meridian, on that ‘great Greenwich hill and tower’ of the celestial seat, will chronometrical time be the ‘right time.’
  • ‘Seventeenth century navigators could tell local time from the position of the Sun, but to determine their longitude, they needed also to know the time at a fixed reference point, i.e. Greenwich, the location of the prime meridian.’
  • ‘But the creation of the prime meridian helped set international standards for how time is measured, for when a day begins and ends - even for how long an hour is.’
  • ‘The prime meridian is the line that separates geographic east from west on the globe.’
  • ‘In a strong sense, then, a fiddler crab's frame of reference - the equator and prime meridian of its entire world - is centered on its burrow.’
  • ‘Key amongst the equipment here was the transit telescope, angled to move only up and down, and from 1750 it was this telescope that defined Britain's prime meridian.’
  • ‘Fourthly, lights out in this wing is extended from the ten thirty curfew that was given to you before your acceptance into this team, to eleven o'clock prime meridian.’