Through his telescope In March 1781, the astronomer William Herschel noticed an object appearing as a disk and not a star and found it to be a new planet beyond the orbit of Saturn. He had discovered the Ice Giant planet Uranus which became the outermost of the seven known planets in our solar system. 

Thirty seven years after Herschel’s discovery, poor tenant farmers Thomas and Tabitha Adams at Lidcot Farm at Laneast near Launceston had their first child of seven children. From these humble beginnings little John Couch Adams was destined for great things. At an early age in the small family library, John was intrigued by the astronomy books he found there. He attended the Laneast village school and learned Greek and algebra. When aged 12 he went to a private school in Devonport run by his mother’s cousin, Rev. John Couch Grylls,  where he learned classics but was mostly self-taught in mathematics. At age 16 in 1835 he observed Halley’s comet from Landulph and the following year started to make his own astronomical calculations, predictions and observations, and to finance his activities became a private tutor. In 1836, because he showed great skill as a mathematician, his parents managed to send him to the University of Cambridge where he graduated in 1843. John was certainly a very bright star!  

Then in 1821, astronomical tables were published making predictions of future positions of the orbit of  Uranus, based on  Newton’s laws of motion. However, later actual observations of the position of Uranus showed that it was not where it should be. It seemed that the gravity of some unknown object could be affecting it or “perturbing” it. Adams believed that he could use the Uranus data to calculate the mass, position and orbit of this unknown body and in 1843, he began to work on the problem. Two years later, Adams attempted to communicate his findings to Cambridge Observatory and the Astronomer Royal.  

Meanwhile, in 1845 French astronomer Urbain Le Verrier had independently come to the same conclusion as Adams and did his calculations to pinpoint where you would find the new planet. The British Astronomer Royal, George Airy, saw Le Verrier’s work so a desperate rivalry race began for the British to beat the French in actually finding and observing the planet. The search was begun by Cambridge University Observatory but Johann Galle at Berlin Observatory first spotted Neptune on 23 September 1846 after using Le Verrier’s calculations. Both Adams and Le Verrier had independently used their maths skills to tell astronomers where they would find planet Neptune, the second Ice Giant. In 1846 John Couch Adams graciously publicly acknowledged Le Verrier’s due credit in finding Neptune and as President of the Royal Astronomical Society from 1874 to 1876, he presented the RAS Gold Medal of the year to Le Verrier.

So, finding Neptune using maths; not bad for a Cornish farmers son!  

Glynn Bennallick