December 2004 - Materials Science Institute - University of Oregon

Planetgate
over the years, some historians have questioned this
orthodoxy. One of the fi rst, half a century ago, was British astronomer
William M. Smart, who had inherited a collection of
Adams’s scientifi c papers. In the late 1980s Allan Chapman of
the University of Oxford and Robert W. Smith, then at Johns
Hopkins University, identifi ed additional relevant documents.
And since the late 1960s Dennis Rawlins, an independent analyst
based in Baltimore, has gone even further and suggested
that 19th-century British astronomers consciously faked—or
at least sexed up—the dossier.
These doubts might have been put to rest had historians
been able to consult the actual documents that Airy cited. But
beginning in the mid-1960s, whenever they requested the fi le,
Royal Greenwich Observatory (RGO) librarians said it was
“unavailable.” Its whereabouts constituted a mystery almost as
compelling as the Neptune saga itself. How could documents
related to one of the most glorious and important events in the
history of astronomy just go missing?
Both Rawlins and the library staff strongly suspected that
the fi le was in the hands of astronomer Olin J. Eggen, who had
served as chief assistant to the Astronomer Royal in the early
1960s. He had borrowed it to write biographical articles on
Airy and Challis, making him the last person known to have
consulted it. But Eggen, who subsequently moved to Australia
and then Chile, denied having the fi le, and the library staff,
fearful that he might destroy the documents (if he indeed had
them) to cover his tracks, was reluctant to press him too hard.
The mystery endured until October 1998, more than 30
years after the fi le had last been seen. Eggen died on the second
day of that month, and as colleagues were going through his
apartment at the Chilean Institute of Astronomy, they came
across the missing documents (along with many invaluable
Overview/Neptune Discovery
■ The early 19th century had its own version of today’s
dark matter problem: the planet Uranus was drifting
off course. The mystery was solved in 1846, when
observers, guided by theorists, discovered Neptune.
Its gravity could account for Uranus’s wayward orbit.
■ Historians have traditionally apportioned credit between
a French theorist, Urbain Jean Joseph Le Verrier, and
an English one, John Couch Adams. Le Verrier’s
role is undisputed, and so was Adams’s—until the
mid-20th century.
■ Just as more historians were beginning to reexamine
Adams’s role, a sheaf of crucial documents went
missing from a British archive. It surfaced in Chile
in 1998. The authors came across other crucial
documents this past summer.
■ The bottom line is that Adams did some interesting
calculations but deserves no credit for the discovery.
books from the RGO library). They crated up the materials,
weighing over 100 kilograms, in two large tea chests and returned
them to the University of Cambridge library, where the
RGO archives are now housed. (The staff immediately made
backup copies.) This fortunate recovery, as well as the discovery
of relevant documents in other archives, has allowed us to
reexamine Neptune’s discovery from a new perspective.
Off Course
five planets—Mercury, Venus, Mars, Jupiter and Saturn—are
easily visible with the naked eye and so have been
known from time immemorial. The fi rst to be discovered telescopically
was Uranus. On the night of March 13, 1781, William
Herschel, a German-born English organist and amateur
astronomer, was carrying out what he called a review of the
heavens, a systematic sweep of the contents of the night sky
with his homebuilt six-inch-aperture refl ecting telescope. He
recognized immediately that the tiny yellow-green disk he came
across in the constellation Gemini was an interloper, perhaps a
comet. Subsequent observations and computations by other astronomers
established, however, that Herschel’s object was not
a comet, which would have had a highly elliptical orbit. It was
a full-fl edged planet, a body moving in a stable, nearly circular
orbit around the sun at a distance about twice that of Saturn.
The idea that our solar system harbored a whole other
94 SCIENTIFIC AMERICAN DECEMBER 2004
COPYRIGHT 2004 SCIENTIFIC AMERICAN, INC.
preceding pages: NASA/JPL (Neptune);
ARCHIVE OF THE LIBRARY OF ASTROPHYSICAL INSTITUTE POTSDAM (sky map)