350 years and counting: three and a half centuries of perseverance, ingenuity and public duty at the ROG, by Dr Louise Devoy

25 years later: from a group of enthusiasts and friends to the Flamsteed Astronomy Society

It all started on 11th September 1999 with just a few enthusiasts and a shared interest and passion for astronomy. Some 25 years later, the Flamsteed Astronomy Society, as it became known, celebrated its anniversary with a look back into the archives with Chair Bobby Manoo. Reading the early newsletters and correspondence, the common thread is as true today as it was back then: a group of friends meeting to discuss and celebrate a hobby, with talks, trips, and workshops. This has also included the occasional special event, with the Venus transit, solar eclipses, and Stargazing Live all featuring the Society heavily in local and national media.

A journey through time: 350 years of the Royal Observatory Greenwich

The name of the society also celebrates the strong links and support from our host, the Royal Observatory Greenwich (ROG), as it celebrates its 350-year anniversary. To tell us more, we heard from Dr Louise Devoy, senior curator at the Royal Observatory Greenwich, who deftly condensed over three centuries of history into just 40 minutes.

What would become the ROG repurposed an old hunting lodge, perched on a hill in a royal park - away from the city (at the time!) but close to the river for easy access to the city of London. Inside, just a few instruments and astronomers were tasked with understanding our place in the world, and how to navigate across it. This remit, however, would change rapidly with the expanding city and with expanding trade routes.

Investing in navigation for the betterment of trade necessitated solving the longitude problem. An early proposal used observations of the Moon against the fixed background of stars, and this was the method that the first Astronomer Royal, John Flamsteed, was asked to verify at the new observatory. The method works well, but with some caveats – angles needed to be accurately measured, two observers needed to communicate their data, and some rather complex mathematics needed to be solved. Doing all this from the moving deck of a ship was clearly not ideal.

So, a better solution was needed, culminating in the Longitude Act of 1714 offering a prize of £20,000 to the best solution. Given this is worth some £3.5 million today, the competition received a lot of interest, with proposals overseen by the ROG. John Harrison finally delivered a winning instrument with the H4 - the fourth in a series of clocks that proved its concept with two trips to Jamaica and Barbados around 1765. And, after proving that other watchmakers could reproduce the design, he finally claimed his prize.

Greenwich has always been synonymous with time. In 1818, the Admiralty took over the ROG, and the sixth Astronomer Royal, John Pond, was asked to focus on calibrating marine chronometers against the stars. He also modernised the observatory substantially, including installing the famous red time ball, which drops every day at 1pm in view of tall ships on the Thames to set their clocks.

Ongoing technical advances included the use of the telegraph to remotely set clocks, allowing their installation in train stations and linking the ROG to other observatories across the globe. This was key to the observations of the 1874 transit of Venus. With different observations made by different observatories, timed by telegraph, the Sun–Venus distance was calculated and the scale of the solar system better understood.

The Flamsteed Astronomy Society was also able to witness history by observing the rare transits of Venus in both 2004 and 2012 - not to measure distances this time, but simply to marvel at the spectacle. Members gathered at sunrise on Blackheath to catch the final stages of the 2012 transit, using modern equipment that Flamsteed could only have dreamt of.

Who knows what technical advances will occur in the next 25 years? But one thing is for sure: the friends will always be here.

Pictures from the event (by Mike Meynell):