Wednesday marked the 250th birthday of one of York’s greatest sons. The deaf astronomer John Goodricke, who from his flat in Treasurer’s House observed a type of variable star that ultimately helped us measure the size of the universe, was born in Holland. But when he was a few years old his English parents returned to this country and settled in York, possibly somewhere near Museum Street.

The Goodrickes were an English aristocratic family with an ancestral home, Ribston Hall, near Knaresborough. They were “essentially country squires of the fox-hunting type”, says Linda French, professor of physics at Illinois Wesleyan University in the US who has been researching Goodricke’s life.

John was profoundly deaf from early in his life. His parents sent him to the Thomas Braidwood Academy for the Deaf and Dumb in Edinburgh and then, at 14, to the Warrington Academy, where he studied maths, natural philosophy and astronomy.

After three years he left Warrington and, in 1781, moved into an apartment in Treasurer’s House owned by his family. He began keeping an astronomical journal, and joined forces with another young astronomer, his distant cousin Edward Pigott, who lived in Bootham.

It was an ‘age of wonders’ when men of science were training their telescopes on the heavens. A few months earlier, William Herschel had discovered the planet Uranus from his home in Bath.

Together, Goodricke and Pigott began observing Algol, the ‘winking demon’, a star which every three days became dim for several hours.

Pigott watched it from an observatory in the garden of his father’s home in Bootham, Goodricke from his window in Treasurer’s House. In his journal entry for November 12, 1782, the 18-yearold Goodricke records his astonishment at the star’s behaviour: “This night I looked at Beta Persei (Algol) and was much amazed to find its brightness altered,” he wrote.

Extraordinarily, Goodricke and Pigott worked out what was causing Algol to go dim: another planet or star was orbiting it, and every three days passed between us and the star, blocking out part of the Algol’s light.

“Today, astronomers find planets around other stars using the principles put forward by Goodricke and Pigott,” says York astronomer Martin Lunn. “Their ideas were 200 years ahead of their time.”

The pair hadn’t finished. On September 10, 1784, they discovered not one but two more variable stars: Beta Lyra and Eta Aquila. They sent reports to The Royal Society: reports which must have caused a sensation. Until then, only four variable stars had been known: these two young York astronomers had found two more in a single night.

These later stars were what is now known as Cepheid variables, which vary in brightness because the stars themselves pulse. More than a century after Goodricke’s time, such variables were used to measure how far away other galaxies are – giving us a grasp of how big our universe is.

Goodricke died aged 21, possibly of pneumonia.

He is buried in Hunsingore, 20 miles west of York. But his place in the history of science is secure.