I have read the book. Obviously, I had to watch the movie. And now the series…
And typical to my weird, obsessive self, I was reminded of the minuscle (literally, nanoseconds, or even smaller) experience of time travel that happened with me. Well, technicality is in the details, but I kid you not!!
Latitude and Longitude – An Overview:
Very very briefly….despite the equator being an imaginary line across the land and sea, its physical effects are indisputably real. The sun, for example, sets and rises in a matter of minutes over the boundary line between the Northern and Southern hemispheres, the earth’s diameter is slightly wider here on account of the force of its rotation: creating a phenomenon known as the ‘equatorial bulge’ – making the earth an oblate spheroid rather than a sphere as it is commonly known. However, when it comes to defining Longitude, it is a little more slippery and complicated. Bisecting the planet from the North Pole to the South, Longitude 0º could technically be anywhere, with no signifying geographical phenomena to dictate them. A Prime Meridian is needed to define zero longitude so that you can accurately determine your geographical existence. If you measure how far you are from the Prime Meridian (Longitude) and how far you are from the Equator (Latitude) you can combine the results to pinpoint your place on the planet. In more technical detail, the Meridian Line, or the Prime Meridian (Longitude 0º), separates the eastern and western hemispheres just like the Equator separates the northern and southern.
In short, where longitude is the distance east or west of the Prime Meridian line, latitude is measured by the distance north or south of the equator. And, the intersection between these two invisble lines is in the middle of the Atlantic Ocean!
Prime Time – Choosing Greenwich Meridian:
Since the late 19th century, the Prime Meridian at Greenwich has served as the reference line for Greenwich Mean Time, or GMT. Before this, almost every town in the world kept its own local time. There were no national or international conventions which set how time should be measured, or when the day would begin and end, or what length an hour might be. So all those calls that you make to your friends to check “when they will arrive” at your meeting point, and the excuses that they usually use…. those would have been totally legit and acceptable if GMT was not in place! When the railway and communications networks expanded in the 1850s and 1860s, there needed to be an international time standard. Greenwich was chosen as the centre for world time.
The establishment of the Prime Meridian at Greenwich has given the world the means to measure and to share time – this totally invented point of significance has an objectively visible impact on the real order of the world as we know it. Today, in London, you can straddle two hemispheres at the same time and stand upon the official centre of time. But, it took a global meeting to come to this decision that allows you to enjoy this selfie moment!
While the position of the Prime Meridian is actually rather arbitrary and could theoretically be located anywhere, its location through Greenwich was agreed at the International Meridian Conference of 1884 because it was the most popular candidate. The Greenwich Meridian was chosen as the Prime Meridian of the World in 1884 by forty-one delegates from 25 nations. By the end of the conference, Greenwich had won the prize of Longitude 0º by a vote of 22 to 1 against (San Domingo), with 2 abstentions (France and Brazil).
Clearly, the fact that an International conference was required to determine objectivity of time measurement shows how tumultous the order of the world is. Imposing measurement was seen as way of extending influence and world domination. USA had already chosen Greenwich as the basis for its own national time zone system. Britain had been using the Royal Observatory in Greenwich as its Prime Meridian since 1721. In fact, before the conference in 1884, roughly ten other prime meridians were also in use, including ones through various other cities including Paris and Cadiz. Post-conference, since France decided to abstain from the voting, they continued to use the Paris Meridian till 1911.
Dawn of Time:
The Observatory was commissioned by Charles II in 1675 and the recognition of astronomy’s significance for cartography and navigation was hugely influential in its inception. Built on the ruins of Greenwich castle, selected for its solid foundations and high vantage point, it was Britain’s first state funded scientific institution. However, precision was literally the “need of the hour” with further developement and expansions within the colonial realm.
The first Astronomer Royal, John Flamsteed devised the concept of ‘mean time’ as the average length of the solar day. The first public time signal in UK came from the Royal Observatory in 1833 with the first dropping of the Time Ball – at 12:55 pm GMT the ball was hoisted halfway up its pole before being dropped from the top at 13:00 precisely. It is a signal that continues to this day. GMT was officially adopted as ‘railway time’ in 1847 and the Master Clock was installed at Greenwich in 1852.
From then on, it was sent by telegraph to cities around the UK and from 1866 sent by the new transatlantic submarine cable to Harvard University in the US, who began to run their own industry by British time. As such, 72% of the world’s industry at that time was already operating according to GMT – a definite historic victory for British commercial power, and empirical science.
Locating Prime Time: Did it move?
In 1884 the Prime Meridian was defined by the position of the large ‘Transit Circle’ telescope in the Observatory’s Meridian Observatory. The transit circle was built by the 7th Astronomer Royal, Sir George Biddell Airy, in 1850. The cross-hairs in the eyepiece of the Transit Circle precisely defined Longitude 0° for the world. As the Earth’s crust is moving very slightly all the time the exact position of the Prime Meridian is now moving very slightly too, but the original reference for the prime meridian of the world remains the Airy Transit Circle in the Royal Observatory, even if the exact location of the line may move to either side of Airy’s meridian. The Royal Observatory lies at Longitude 0° by the original definition of Airy’s Transit Circle, and at Latitude is 51° 28′ 38” N.
Between 1984 and 1988, an entirely new set of coordinate systems were adopted based on satellite data and hence, required a prime meridian that defined a plane passing through the centre of the Earth. As such, by international agreement in 1984, the IERS Reference Meridian, also known as the International Reference Meridian or IRM, was defined as the true prime meridian of the world. The IRM passes 102.5 metres to the east of the historic Prime Meridian of the World at the latitude of the Airy Transit Circle here. The entire Observatory and the historic Prime Meridian now lie to the west of the true prime meridian.
How to stand on Prime Meridian:
To experience the best of “time travel”, irrespective of the fickle moods of UK weather gods, it is very important that you stand on the line properly. Ensure that your foot is placed either side of the line. Because really, when you think about it, one foot is a little behind the other in time.
- Opening Times: 10.00am – 17.00pm. Last admission 30 minutes before closing.
- Cost: £10 for adults (£7.50 concessions). Entry for children under 16 is free. The £10 entry is an annual pass (visitors are able to return as many times as they like within 12 months for no additional charge).
- Admission to the Royal Observatory’s Astronomy Centre which houses three state-of-the-art modern astronomy galleries is free.
- Planetarium London Ticket Prices: £6.50 adults, £4.50 children and concessions
- The Origins of the Greenwich Prime Meridian (check out the extensive reference link provided here for some extra historical facts!)
- History of Time and Space
- Royal Museums Greenwich
- Shepherd’s Clock
- Longitude found: Story of Harrison’s clocks
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