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On November 1st, 1884 U.S. President Chester Alan Arthur convened the International Meridian Conference with delegates from 25 nations in Washington, D.C. where they established time zones for the whole world. (You can read a scanned copy of the Protocol of the Proceedings here.)
They chose the Greenwich Observatory in Greenwich, UK to be the place for 0 degrees since most marine maps already used the lines of longitude with Greenwich as the the reference point since 1675. (As seen in photo.)
The US used the Washington Meridian which then ran through the Old Naval Observatory in the Foggy Bottom neighborhood for its state boundaries, and the Greenwich Meridian already for all nautical purposes, so they were able to easily adapt to the change.
Why Do We Need a Prime Meridian?
Before the Industrial Revolution, travel took days. If we bothered to travel at all, we walked, sailed or rode horseback. Travel took so long we didn’t think about time differences between towns.
With the invention of the steam engine travel was never the same again. Railroads were linking states and even whole continents. They could travel at about 12 mph, which was fast enough to get from one city to another in the same day.
This caused a problem with telling time because every town set their own time based on when the sun was directly overhead for 12 noon. The train schedules based their arrival and departure times on the time set by each city which made time keeping rather erratic. With steam engines on the scene, a more uniform system of calculating time world wide was necessary.
Why Do We Have the Lines of Longitude?
The earth spins 360 degrees – a full circle – in 24 hours. The delegates divided the circumference into 24 one hour sections, each 15 degrees and approximately 69 miles wide. Now time is set around the world based on the Prime Meridian with each line of longitude on the East an hour earlier than the one before and each line to the West an hour later than the one before.
Here it is in a one minute nutshell:
[iframe src=”http://www.youtube-nocookie.com/embed/j5bSn_pzuWY?rel=0″ width=”100%” height=”480″]
Maybe Maddie can explain it better with her watermelon and a quest for the longest day ever:
[iframe src=”http://www.youtube-nocookie.com/embed/4ZuDzFjzoqc?rel=0″ width=”100%” height=”480″]
If you’d like a way to explain the Eastern and Western Hemisphere on maps to your kids, this online Flash presentation is great.
Prime Meridian Activity
3 Teacher Chicks have a fantastic tutorial on turning pumpkins – which are very seasonal right now – into globes.
Get kids to paint their pumpkins, allow them to dry and then mark the Prime Meridian with a ribbon, yarn or dots like Maddie did in the above video.
World Time Zones
Here are all the time zones as they stand today:
Click to see your time – right this second – in relation to the time in other cities of the world. (If you travel or have a loved one in a different time zone, bookmark this page for a quick and easy reference.)
Here is a printable map of the Time Zones of the World.
Here is an interactive time zone map of the world so kids can see what time it is at their house, and then other cities of the world with just a click.
US Time Zones
Here is a printable map of all the US time zones. Which one do you live in? Get the kids to mark it with a sticker or a marker.
Canadian Time Zones
Prime Meridian Stuff
Available online from the Royal Museums Greenwich.
Also available in black.
I hope you and yours have a Happy Prime Meridian Day.
P.S. Just a note to let you know that I don’t make any money on your purchase of the Prime Meridian merchandise from the Museum – I just thought they were fun and decided to add them here for you to see.
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Subscribe today & don't miss a thing!
Once a week we'll tell you the upcoming daily celebrations & the articles you may have missed.