Plutocrats

Yes, it's Pluto Week here at Blogito Ergo Sum. Yesterday's New York Times online has a good summary of the Pluto debate. One line stood out:

The planet (if that is what it is) has been an oddball ever since Clyde Tombaugh spied it wandering in the outer reaches of the solar system beyond Neptune in 1930.

This implies that Tombaugh--who was at Lowell Observatory and thus he is the only American to have discovered a planet (for the time being, of course)--looked in the telescope one night and spotted little Pluto out of the blue. Actually, the existence of a planet beyond the orbit of Neptune had been theorized for decades before it was actually found--Percival Lowell (founder of the observatory) being among them. The reason they suspected something being there was that there were certain eccentricities in the orbit of Neptune that could only be explained by another large object in the vicinity. In fact, this was exactly how Neptune had been discovered in 1846--thanks to perturbations in the orbit of Uranus. Some astronomers also simply felt that, "Hey, we found Neptune. Maybe there's another one out there." So the search was on.

Lowell died in 1916, but his observatory continued the work. How? Far more laboriously than you would think. Clyde Tombaugh--a 24-year-old assisitant hired for the project--attached a camera to a telescope and took a series of photographic plates of the night sky in the general vicinity in which the object was believed to be, each taken one to two weeks apart. He would then place two separate plates into a device called a "blink comparometer" which essentially toggled between two different pictures. The goal was to see which of the many many white dots had moved (stars are fixed, while planets move about). It was a long, tedious, laborious process (they had a demonstration of the process when I took the tour--it kind of reminded me of analyzing TrendWatch's historical survey data...)--but on February 18, 1930, Tombaugh announced he had found it.

The new planet went nameless for a while, until a an 11-year-old British girl (whose father had connections in the astronomical community) suggested "Pluto." Cables were sent across the pond and to Arizona, where the directors of Lowell University rather liked the idea--especially in that the inital "Pl" are Percival Lowell's initials. Since they had naming rights, they chose "Pluto."

What's rather ironic about all this is that astronomers later discovered that Pluto was too small to have affected Neptune's orbit--and, in fact, the original "perturbations" were the result of an inaccurate estimate of Neptune's mass (19th-century astronomers were good but were working with pretty primitive resources). It's a good thing Tombaugh found something--imagine going on a wild goose chase of astronomical proportions!