International datelines notwithstanding, the Greenwich Meridian is the invisible line of longitude at which the year 2000 will officially begin. The photographer Brian Harris plots the line's course through England, while Charles Jennings tells its story

THE GREENWICH Meridian is the prime meridian in the world, the point at which the universal day starts, and at which the year 2000 will begin. It sounds like a God-given direction - Place the meridian here - or the result of some inescapable natural law; but in reality it is the product of accident and historical forces.

As ever, longitude is behind it all. But where do you put longitude 0 on the map? If the imaginary lines of longitude run from the North Pole to the South, and divide the earth up into 360 imaginary degrees, where do you start? Where do you put a line so that at any point of the globe you can fix your east-west position by working out how far you've travelled from your given starting point - a starting point, what's more, that's recognised by the rest of the world?

Hipparchus, the Greek astronomer, first had a go at fixing it on the island of Rhodes. Ptolemy, the Egyptian astronomer and geographer, then moved the prime meridian to the Canary Islands - the west-ern edge of the known world. Pope Alexander VI tried to set it just west of the Cape Verde Islands; while Philip II of Spain moved the meridian to the city of Toledo. In the 17th century, Cardinal Richelieu called an international conference to settle the matter - with the westernmost of the Canary Isles coming out as the chosen spot. This was certainly adhered to by the French for the next 100 years; but for the rest of the world things went on much as before, each nation tending to use whatever prime meridian it felt like. Things only began to change significantly with Nevil Maskelyne's Nautical Almanac of 1767. At the time, the most reliable way for mariners to work out their longitude in the middle of a large and featureless ocean was to examine the positions of certain known heavenly bodies with an instrument such as a sextant, and then look up the results in a table giving the positions of moon and stars for any given date. They could then work out their position from the initial longitude used by the maker of the table. Maskelyne's Nautical Almanac was the first reliable and practical almanac in the world, and - since Maskelyne was Astronomer Royal at the Greenwich Royal Observatory - it took the Greenwich Meridian as its starting point. Immediately, British navigators started to use it, alongside the British-made charts, which set longitude 0 at Greenwich. Other nations also adopted the Nautical Almanac, which meant that their charts had to have the same longitude arrangement as British ones.

But it was clear that some kind of agreement was needed to formalise the situation. The final outcome was decided at the International Meridian Conference, held in Washington DC in 1884. The United States offered to host the conference as it had "the greatest longitudinal extension of any country traversed by railway and telegraph lines". In due course, 41 delegates from 25 countries arrived. A month of wrangling and voting later, and the key questions had been answered. All the countries had voted in favour of the principle of a single prime meridian. Twenty-two out of 25 voted for Greenwich as the prime meridian. Twenty-three out of 25 voted in favour of the principle of the universal day, beginning at the prime meridian.

And where would the fixed point be set? Where, exactly, was the prime meridian on which all this was to hinge? It was "the centre of the Transit Instrument at the Observatory at Greenwich". This is longitude 0, and on one side is the western hemisphere of the world; on the other is the eastern. If you go there, you can - and most people do - bestride the brass strip which marks the meridian and stand with one foot in both hemispheres, almost as if this were the only place in the world where such a thing is possible. But, of course, longitude 0 describes an imaginary line from Pole to Pole, so you could also stand on a spot just outside Le Mans, in northern France, or near the town of Caspe, in north-eastern Spain, or stand in the western Sahara. All these would mark the prime meridian just as well.

Except that Greenwich created it. And if accident and historical forces hadn't colluded, then longitude 0 could now be in Paris, or Madrid or Washington, or (as Willem Blaeu, the 17th-century cartographer decided) on the highest point of the island of Tenerife. But Greenwich is where it all starts.

This is an extract from `Greenwich: The Place Where Days Begin and End' by Charles Jennings (Little, Brown, price pounds 10, or telephone 0181 324 5515 to order a copy for pounds 8, incl p&p)

Arts and Entertainment
Call The Midwife: Miranda Hart as Chummy

tv Review: Miranda Hart and co deliver the festive goods

Arts and Entertainment
The cast of Downton Abbey in the 2014 Christmas special

tvReview: Older generation get hot under the collar this Christmas

Arts and Entertainment
Dapper Laughs found success through the video app Vine

comedy Erm...he seems to be back

Arts and Entertainment
Wolf (Nathan McMullen), Ian (Dan Starky), The Doctor (Peter Capaldi), Clara (Jenna Coleman), Santa Claus (Nick Frost) in the Doctor Who Christmas Special (BBC/Photographer: David Venni)

tvReview: No ho-ho-hos with Nick Frost's badass Santa

Arts and Entertainment
Bruce Forsyth and Tess Daly flanking 'Strictly' winners Flavia Cacace and Louis Smith

tv Gymnast Louis Smith triumphed in the Christmas special

Arts and Entertainment
Rhys says: 'I'm not playing it for laughs, but I have learnt that if you fall over on stage, people can enjoy that as much as an amazing guitar solo'
musicGruff Rhys on his rock odyssey, and the trouble with independence
Arts and Entertainment
Krysia and Daniel (Hand out press photograph provided by Sally Richardson)
How do today's composers answer the challenge of the classical giant?
Have you tried new the Independent Digital Edition apps?
Arts and Entertainment

ebooksNow available in paperback
Arts and Entertainment

Shenaz Treasurywala
Arts and Entertainment
Jason Watkins as Christopher Jefferies
Arts and Entertainment
Star Wars Director JJ Abrams: key character's names have been revealed
Arts and Entertainment
Pharrell Williams won two BBC Music Awards for Best Song and International Artist
Arts and Entertainment
Mark, Katie and Sanjay in The Apprentice boardroom
Arts and Entertainment

Film The critics but sneer but these unfashionable festive films are our favourites

Arts and Entertainment
Frances O'Connor and James Nesbitt in 'The Missing'

TV We're so close to knowing what happened to Oliver Hughes, but a last-minute bluff crushes expectations

Arts and Entertainment
Joey Essex will be hitting the slopes for series two of The Jump


Who is taking the plunge?
Arts and Entertainment
Katy Perry as an Ancient Egyptian princess in her latest music video for 'Dark Horse'

Arts and Entertainment
Dame Judi Dench, as M in Skyfall

Arts and Entertainment
Morrissey, 1988

Latest stories from i100
Have you tried new the Independent Digital Edition apps?

ES Rentals

    Independent Dating

    By clicking 'Search' you
    are agreeing to our
    Terms of Use.

    A Christmas without hope: Fears grow in Gaza that the conflict with Israel will soon reignite

    Christmas without hope

    Gaza fears grow that conflict with Israel will soon reignite
    After 150 years, you can finally visit the grisliest museum in the country

    The 'Black Museum'

    After 150 years, you can finally visit Britain's grisliest museum
    No ho-ho-hos with Nick Frost's badass Santa

    No ho-ho-hos with Nick Frost's badass Santa

    Doctor Who Christmas Special TV review
    Chilly Christmas: Swimmers take festive dip for charity

    Chilly Christmas

    Swimmers dive into freezing British waters for charity
    Veterans' hostel 'overwhelmed by kindness' for festive dinner

    Homeless Veterans appeal

    In 2010, Sgt Gary Jamieson stepped on an IED in Afghanistan and lost his legs and an arm. He reveals what, and who, helped him to make a remarkable recovery
    Isis in Iraq: Yazidi girls killing themselves to escape rape and imprisonment by militants

    'Jilan killed herself in the bathroom. She cut her wrists and hanged herself'

    Yazidi girls killing themselves to escape rape and imprisonment
    Ed Balls interview: 'If I think about the deficit when I'm playing the piano, it all goes wrong'

    Ed Balls interview

    'If I think about the deficit when I'm playing the piano, it all goes wrong'
    He's behind you, dude!

    US stars in UK panto

    From David Hasselhoff to Jerry Hall
    Grace Dent's Christmas Quiz: What are you – a festive curmudgeon or top of the tree?

    Grace Dent's Christmas Quiz

    What are you – a festive curmudgeon or top of the tree?
    Nasa planning to build cloud cities in airships above Venus

    Nasa planning to build cloud cities in airships above Venus

    Planet’s surface is inhospitable to humans but 30 miles above it is almost perfect
    Surrounded by high-rise flats is a little house filled with Lebanon’s history - clocks, rifles, frogmen’s uniforms and colonial helmets

    Clocks, rifles, swords, frogmen’s uniforms

    Surrounded by high-rise flats is a little house filled with Lebanon’s history
    Return to Gaza: Four months on, the wounds left by Israel's bombardment have not yet healed

    Four months after the bombardment, Gaza’s wounds are yet to heal

    Kim Sengupta is reunited with a man whose plight mirrors the suffering of the Palestinian people
    Gastric surgery: Is it really the answer to the UK's obesity epidemic?

    Is gastric surgery really the answer to the UK's obesity epidemic?

    Critics argue that it’s crazy to operate on healthy people just to stop them eating
    Homeless Veterans appeal: Christmas charity auction Part 2 - now LIVE

    Homeless Veterans appeal: Christmas charity auction

    Bid on original art, or trips of a lifetime to Africa or the 'Corrie' set, and help Homeless Veterans
    Pantomime rings the changes to welcome autistic theatre-goers

    Autism-friendly theatre

    Pantomime leads the pack in quest to welcome all