In the 17th century, it was pretty difficult to figure out where you were when on a ship at sea. Navigation by stars was the most accurate way, but it was usually just used as a guideline for which direction you were going. The ultimate goal was to know the exact latitude and longitude of your location. Latitude – how far North or South you are – could be measured by looking at the position of the sun or (other) stars over the horizon, but longitude was much harder.
To solve the problem of longitude, King Charles II ordered the construction of the Royal Observatory in Greenwich, and hired an Astronomer Royal, to “find the so much desired longitude of places for the perfecting of the art of navigation”.
In the end, it wasn’t the Astronomer Royal, but a Yorkshire clockmaker who worked out how to determine longitude at sea using a very accurate clock.
Today, the Royal Observatory in Greenwich is most famous not just for celestial-based navigation, but for the Greenwich Meridian. Unlike the lines of latitude, determined by the poles and equator, the lines of longitude are arbitrary. Greenwich was officially declared to be longitude 0° at a conference in 1884, and the line is marked by a metal strip and a long line of tourists in the courtyard of the observatory.
Inside the Observatory buildings are exhibits about astronomy, navigation and time. I thought it would be a fitting destination to mark my last science travel post of 2013, because it’s not just about science travel, but also about the science of travel – and time!
In 2014 I’ll start writing about science travel destinations that I haven’t visited yet, but would like to visit. Latitudes and longitudes still to be determined.
And don’t forget to check out our Have Science Will Travel map:
The Finch and Pea 
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