THE “most influential schoolgirl in astronomical history” has died at the age of 90.

Venetia Burney Phair was just 11 when, over breakfast in North Oxford, she named the former planet Pluto.

Sitting with her grandfather, Falconer Madan — a former head of the Bodleian Library — on the morning of March 14, 1930, she read about the discovery of the ninth planet in The Times.

Venetia, who had enjoyed an outdoor lesson on planetary science in the University Parks the previous year, was aware that planets were named after classical gods.

Her suggestion that Pluto, the Roman god of the underworld, was a suitable title for the distant body — stripped of its status as a planet in 2006 — was taken by her grandfather to his friend Herbert Hall Turner, a former president of the Royal Astronomical Society. The idea was then sent by telegram to the Lowell Observatory in Arizona, which had the planet's naming rights, and the title was confirmed on May 1, 1930.

To celebrate, Mr Madan gave £5 to Venetia and to her school, which spent it on a wind-up gramophone.

Ginita Jimenez, director and producer of a documentary on the story of the planet’s naming, said: “She was the cleverest 11-year-old, certainly the most influential schoolgirl in astronomical history.

“As soon as I met Mrs Phair I understood why.

“Here was a sharp mind, a composed and vigorous lady, someone who appeared, intellectually, physically and spiritually, 30 years younger.

She added: “I am honoured to have shared those last years of Venetia’s life and for her to have trusted a young filmmaker with her extraordinary contribution to astronomical history.”

She died in Surrey on April 20.