As Neptune is currently in our night sky, I thought I would dedicate this month’s feature to saying a little more about it. The story starts with the discovery of Uranus by William Herschel in 1781 - it was so unexpected, it took two years to prove it was a planet.

Its motion was followed closely by specialists in planetary orbits across Europe, and it was soon found to be wandering in a strange way. This was most pronounced in 1822, when in fact Uranus was overtaking Neptune on the inside. All planets tug on each other – gravity works that way.

Two mathematicians, Cornishman John Couch Adams and Frenchman Urbain Le Verrier, worked out that the strange wandering could be due to another so far undiscovered planet.

Le Verrier could not find an observatory to try and track it down, but the British Astronomer Royal, GB Airy, got Prof James Challis to start a search in the right area, which was packed with faint stars. Nonetheless, within a few days he had recorded Neptune’s position twice; however, he did not repeat the analysis to prove his “stars” had moved.

Le Verrier got hold of the Berlin Observatory and two young astronomers set to work and found it without difficulty.

Today, evidence of Adams’ work can be found all over Cornwall, including memorials in Truro Cathedral and St Sidwell & St Gulvat’s church in his birthplace of Laneast, and records and artifacts found in Kresen Kernow, Roseland Observatory, and the library and museum in Launceston.

The main textbook - Neptune: From Grand Discovery to a World Revealed: Essays on the 200th anniversary of the birth of John Couch Adams - was driven from Cornwall and published by Springer.

Brian Sheen FRAS runs the Roseland Observatory at Truro High School for Girls. Visit www.roselandobservatory.co.uk and on www.facebook.com/roselandobservatory