The "trans-Neptunian body," once known and loved as the solar system's ninth planet, was confirmed in photographs in February 1930. But what to call this cold, distant planet? To an 11-year-old British girl, the name was obvious: Pluto, after the mythical Roman god of the underworld.

Venetia Phair (née Burney), who died last month in Banstead, England at age 90, was eating breakfast with her mother and grandfather on March 14, 1930, the day papers reported the new planet, The New York Times writes. The girl suggested it be named Pluto, and her grandfather, a retired librarian at Oxford, mentioned the moniker to an astronomy professor there, who liked it so much, he fired a telegram off to the Lowell Observatory in Flagstaff, Ariz., where the discovery was made.

Young Phair wasn't the only one hoping to bestow a name on the solar system's newest member. A veritable pantheon of titles—from Atlas to Zeus—flew through the astronomy community, and for a time, it looked like Minerva would win out (until people were reminded that it was already the name of an asteroid).

But on May 24, 1930, the new planet was officially christened Pluto, in part because the first two letters stand for Percival Lowell, who hypothesized about the ninth planet's existence and for whom the Lowell laboratory was named.

"I certainly was thrilled," Phair told NASA in a 2006 interview about finding out her name had been chosen. The 11-year-old hadn't been losing any sleep over the matter, though. "I'd just really forgotten about it for the intervening months." For the winning name, her grandfather rewarded her with a five pound note, the generosity of which, she told the BBC "was unheard of then."

The next couple of decades saw a surge of popularity for the appellation, including the element plutonium (discovered in 1941) and, of course, Mickey Mouse's dog. The latter, she told the BBC in 2006, was a source of annoyance. "Now it has been satisfactorily proven that the dog was named after the planet, rather than the other way round. So one is vindicated," she said.

So what did Phair have to say about the demotion of Pluto in 2006 to a dwarf planet? "At my age, I've been largely indifferent to [the debate]," she told the BBC that year. "I suppose I would prefer it to remain a planet."

She is survived by her son and an asteroid, discovered in 1987, that bears her maiden name: 6235 Burney.

Image courtesy of NASA