The Prime Meridian has Moved

Holy Crap!

I recently travelled to London, and stayed at a hotel in Canary Wharf. As part of my morning routine, I run. One morning, as I headed across the Isle of Dogs alongside the River Thames, I was presented with a view of the Royal Observatory at Greenwich across the river from where I was running. As I stopped to take a pic, it struck me that I should find out if I was standing on the Prime Meridian. And that is when I learned.

The Prime Meridian is not where it is purported to be.

As I learned, the “initial meridian” (aka Prime Meridian) is a line that was agreed on by 41 delegates from 25 nations at The International Meridian Conference in Washington in 1884 to be the line passing through the principal Transit Instrument at the Observatory at Greenwich. This is where the line is drawn.

The real Prime Meridian is actually 334ft (for those metrically minded – 101 metres) to the East of where it is currently marked.

Now, this might not seem like such a big deal, but in our ever more connected and more precise world of geolocation, this is a big deal because it means our geolocation East West measurements are within 334ft of where they should be.

To put this in perspective, I have been thinking of purchasing a new car with self-drive capability recently and this info has put a kibosh on that. All I can visualize is the geolocator on the car putting me only more-or-less on the road; seriously, only more-or-less. What will this do to my insurance premiums.

Still does not seem like such a big deal. What this also does is put an additional spin on time because it shows that GMT could be ~0.2 second off from what it should be.

Imagine time being given in units that are approximate. As an example, Usain Bolt is the 100m Sprint record holder with a time of 9.58 seconds, give or take 0.2 seconds.

With a measurement difference of up to 334 ft, and a time difference of up to .2 seconds, what chaos will ensue when some of us move to GPS measurement and some of us remain on analog devices – sextant, telescope, watch and compass.

And, as far as my running was concerned, I learned that neither the “initial meridian” nor the “new” Prime Meridian pass thru the Isle of Dogs. I would have to get into the middle of the River Thames to achieve my objective. Ah well, time to leave my search for a warmer day.