August 27, 2006

Another Plutonian Casualty?

It's an irresistible story, right down to the quaint names of the dramatis personae. On March 14, 1930, Falconer Madan, the librarian of the Bodleian Library in Oxford, reads his 11-year-old granddaughter Venetia Burney the press story about the discovery of a new planet by the Lowell Observatory in Flagstaff Arizona. She has been studying Greek and Roman mythology and tells her grandfather that the planet should be named Pluto, after the Roman god of the underworld. He relays the suggestion to the Oxford astronomer Herbert H. Turner, who in turn cables it to the Lowell Observatory. When the name is announced on May 1 by Vesto Slipher, the Observatory's director, Venetia is given due credit for her suggestion. After the story is popularized in a 1964 article in Sky and Telescope, "the girl who named Pluto" becomes a favorite topic in popular books about astronomy, and even in her 80's, Venetia is still the subject of news features and interviews.

As long as people are raining on 75-year-old planetary parades, maybe this one is worth some cold-eyed reconsideration as well.

The story has developed some elaborations over the years --some accounts, for example, have Venetia winning a contest to name the new planet. But there's no reason to doubt most of the details as they were originally given. There's no question that Turner forwarded Venetia's suggestion to Slipher, who acknowledged her as the first person to suggest the name in a May 1 observation circular (the formal announcement came later). (See William Graves Hoyt's article "W. H. Pickering's Planetary Predictions and the Discovery of Pluto," Isis 67,4, December, 1976.)

But it's hard to credit that Venetia was actually the first to bring up Pluto as a potential name. In a BBC interview published on January 13, 2006, Venetia Burney Phair herself reported that when her grandfather first went looking for Turner, he turned out to be at a meeting of the Royal Astromical Society in London, where people were naturally speculating on the name of the new planet.

"None of them came up with Pluto. That was another stroke of luck," says Mrs Phair. When Mr Madan eventually caught up with Herbert Hall Turner, the astronomer agreed Pluto was an excellent choice.

No doubt that's what her grandfather or Turner told the 11-year-old -- anyway, it's what I would have told my daughter in similar circumstances. But it's virtually certain that "Pluto" was already being bruited about by the members of the RAS and by astronomers elsewhere, including those at the Lowell Observatory. Inasmuch as the planets were conventionally named after Roman gods, it's hard to think of a choice more obvious than the name of "the god of the regions of darkness where Planet X holds sway," as Roger Lowell Putnam, a trustee of the Lowell Observatory, said on May 25, 1930 in announcing the choice of the new name that would be submitted to the American Astronomical Society and the RAS ("Pluto Picked as the Name for New Planet X Because He Was God of Dark Distant Regions," as the New York Times zeugmatically titled its 5/26/1930 article on the announcement). And the name was all the more appropriate, as Putnam noted, because Pluto was the brother of Neptune and Jupiter (as well as being the son of Saturn, he might have added). But Putnam made no mention of Venetia in the public announcement. And given that astronomers were rifling through the lists of Roman gods from the moment of the new planet's discovery -- and indeed, from well before that date, in anticipation -- it's not credible that Slipher would have opened the telegram containing Venetia's suggestion and said, "Pluto! Now why didn't we think of that one?"

In fact the name Pluto had occurred to other people, and some were already using it. A story in the New York Times on March 25, 1930, two months before Putnam's announcement, reported that the Italian astronomers at the Breara [sic -- actually Brera] Observatory who had photographically corroborated the discovery of Planet X had provisionally given it the name Pluto "because that ancient divinity was related to others for whom planets are named," being "the son of Saturn and the brother of Jupiter and Neptune." (The same story was carried in a March 25 AP dispatch.) Slipher must have known about this well before the date of the stories, since the Lowell Observatory must have been in touch with Emilio Bianchi and the other astronomers who made the observations. And by March 28, the suggestion of Pluto as a name was already being criticized by the astronomer Hans Hoerbiger of Vienna (who argued that since the planet consisted cheifly of frozen water, a name relating to Neptune should have been used.) (NYT 3/29/1930).

But if the name Pluto was adopted from the Italians or was simply in the air, why would Slipher have credited Venetia for playing a decisive role in his May 1 circular? Perhaps he simply felt that the story added a charming note of human interest -- and after all, Venetia really had suggested the name, and crediting her with first discovery would have been seen as a gracious gesture to Turner (a former Astronomer Royal) and the English. Slipher may also have wanted to reserve credit for the name to the Anglo-American sphere, rather than acknowledging that the Italians had come up with it first.

Or perhaps there's an additional explanation. As Hoyt points out in his 1976 article, the name Pluto was also being used by the astronomer William Henry Pickering. A fecund predictor of hypothetical planets, Pickering had conjectured a trans-Neptunian "Planet O" between 1919 and 1928 on the basis of perturbations in the orbit of Neptune, a theoretical rival to Percival Lowell's Planet X, which the Lowell Observatory had set itself to find. Given the rivalry that had developed between Pickering and the Lowell Observatory staff, it's no wonder that Harlow Shapley, the director of the Harvard Observatory, would warn Putnam two days after the discovery was announced that "we shall soon be hearing from W. H. Pickering."

And indeed, in an article published in 1930 in Popular Astronomy shortly after the discovery, Pickering identified the body found by the Lowell Observatory as his Planet O, and claimed priority of publication for the name Pluto, a name he later claimed to have been privately using for some time. When the observatory staff insisted that the body was identical with Lowell's Planet X, a dust-up ensued; in Janurary 1931, Pickering attacked Percival Lowell's work and the "surprising and reckless claims. . . put forth by his active adherents and administrators, backed by very extensive newspaper propaganda." And later, having decided that the object found by the observatory was not one of his hypothetical planets, he objected to the choice of "Pluto" as a usurpation: "Pluto should be named Loki, the god of thieves," he said. (See Hoyt, pp. 563-564.)

There is no way of knowing whether Slipher was aware of Pickering's use of "Pluto" prior to the appearance of Pickering's Popular Astronomy article. But he certainly knew of Pickering's claim before he gave pride of place to Venetia, and that may have given him another motive for crediting her with the suggestion, foreclosing speculation that the name was borrowed from Pickering. Whatever his motives, it isn't plausible that Venetia really was the first person to suggest the name of Pluto. Which is not to deny that she was a very clever young girl.

Posted by Geoff Nunberg at August 27, 2006 01:06 PM