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  • Writer's pictureSara-Jane Armstrong, MA

A Brief History of the Royal Greenwich Observatory in London

What is the Royal Observatory?

The Royal Observatory is a former headquarters of the Astronomer Royal and now the site of London’s Planetarium; home of Greenwich Mean Time (GMT) and the Prime Meridian of the world.

Royal Greenwich Observatory Dome

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Royal Observatory History

Britain has designated an Astronomer Royal since the 17th century, and the position has become one of the most illustrious in astronomy worldwide. The first in the post, John Flamsteed, was assigned by King Charles II the daunting task of creating a comprehensive map of the heavens, accurate enough ‘to find out the so much desired longitude of places for … perfecting the art of navigation’. For this, Flamsteed required an observatory. Designed under the king’s auspices by prolific architect Sir Christopher Wren, the Royal Observatory was completed in 1676. Devoting himself to his mammoth task of mapping the heavens to their full known extent, Flamsteed felt insecure. He didn’t deem his work worthy of publication, thinking it was insufficiently accurate. Isaac Newton and Edmond Halley, finding this nonsensical, went ahead and published it against his will. Flamsteed’s work would change cartography – and navigation – forever.

His published work documented 3,000 stars, as well as the first recorded sighting of the planet Uranus. He accurately calculated the solar eclipses of 1666 and 1668, and recorded the most recent supernova of the time. His records of two comets were amended to state that one comet was travelling in orbit around the sun, a note that came to inspire the observations of Isaac Newton. Flamsteed spent four decades at the Royal Observatory, meticulously mapping every inch of the sky and preparing the way for explorers and navigators for centuries to come. He has enjoyed full credit in posterity: one of the moon’s craters is named Flamsteed, in his honour.

After his death he was succeeded at the Royal Observatory in 1720 by Edmond Halley, best known for the comet that bears his name. Upon arrival at the country’s grandest astrological site, Halley found the observatory ransacked; Flamsteed’s widow had considered its technical equipment to be her late husband’s personal property. Halley’s main task was improving the accuracy of the lunar tables, the information that charted the position of the moon at any given time.

Royal Greenwich Observatory

Later came James Bradley in 1742, Nathaniel Bliss in 1762, and Nevil Maskelyne in 1765. The problem of longitude, mapped along the eponymous imaginary lines that lie east or west of the prime meridian at Greenwich, was solved between these three astronomers, after decades of work on the topic. That prime meridian, where east meets west at Longitude 0°, was determined exactly by Sir George Biddel Airy, who became Astronomer Royal in 1835. The official residence and observatory of the Astronomer Royal moved away from the Greenwich site in the mid-20th century and the title became an honorary one. The work achieved inside the Royal Observatory is responsible for centuries of discovery. Explorers, cartographers, navigators, and scientists the world over owe a debt to the observatory, and to the astronomers who mapped the skies meticulously within.

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