Sky & Telescope - December 2023 - 32

Observing History
niadi, whom he regarded as something of a neophyte, on the
proper method of observing planets, which included the usual
Flagstaff Observatory practice of stopping down the lens of
the telescope in order to match its aperture to the size of the
air cells passing overhead.
Ever since he began observing Mars in 1894, Lowell had
seen no reason to doubt that the Martian atmosphere was
almost always clear. Consequently, he failed to recognize
the dust storm that had rushed across the planet that summer
and instead ascribed its detail-obscuring effects to a
case of bad seeing on Earth. Thus, he had made relatively
sparse observations until late September, when he reported
the discovery of two new " canals " on Mars. His drawing of
September 30th shows the Syrtis Major region Antoniadi had
represented so beautifully 10 days earlier. The difference in
their styles is almost alarming.
Lowell did not receive Antoniadi's drawings until early
November. Since Antoniadi had not stopped down his telescope's
aperture as advised, Lowell thought that the younger
astronomer had been betrayed by poor technique. In Lowell's
opinion, Antoniadi's view of Mars must have been affected
" by a fine imperceptible blurring which transforms the detail
UNDER THE DOME A new copper dome protects the Grand Lunette,
a century after Antoniadi's famous Mars observation. After a hiatus of
several years, the telescope is now available for public viewing.
really continuous into apparent patches. " Antoniadi thought
this line of argument ludicrous. The two men debated for a
while, but in the end, both remained set in their views. Lowell
went to his grave believing in the canals, but the verdict of
truth ultimately fell on Antoniadi's side.
Antoniadi's 1909 work on Mars represents his finest hour.
He made further observations of Mars and Jupiter with the
Grande Lunette in 1911, after which it was closed for some
years due to repairs to the dome. During the First World War,
he devoted a great deal of time to catching up on the backlog
of BAA Mars reports and performed war-related work (what
exactly is unknown) for which he received France's Legion
of Honour. In 1917, he relinquished directorship of the Mars
Section and resigned his membership in the BAA outright. It
seems that the work of preparing the Memoirs and the stress
of the war may have strained his delicate health. But then,
Antoniadi always upheld the ideals of a true amateur. If an
interest became a grind, he broke off from it. As he wrote
to the Astronomer Royal, Frank Dyson, science " must be
cultivated for its own sake, for the pure love of truth, rather
than for the applause or profit that it brings. " He took up
chess again for a while, then returned to Meudon for the
great opposition of Mars in 1924. He also began a long series
of Mercury observations.
In June 1940 the Nazis occupied Paris. Antoniadi's health
was beginning to fail, and despite being of comfortable
means, he shared the lot of most Parisians during this period,
living " by expediency, their meager rations eked out by food
parcels from the country, their apartments heated by stoves
filled with sawdust, " as described by a diarist at the time.
He continued to observe at Meudon and repaired each
year to Juvisy-sur-Orge to mark, with colleagues, the anniversary
of Flammarion's death in 1925. The younger generation
of planetary observers regarded him with awe and dared
not approach him. French astronomer Gérard de Vaucouleurs
noted his " naturally curt manner, " but also acknowledged
that he was " by far the best planetary observer ever
[with] an unsurpassed skill in transferring to paper fleeting
telescopic views. "
Although Antoniadi destroyed all his papers before he died
in 1944 (possibly to avoid them falling into the hands of the
Nazis), he nevertheless conveyed a sense of how he wanted
to be remembered in a 1913 letter to the great American
astronomer Edward Emerson Barnard:
" . . . my only ambition is to defend the truth and write
nothing susceptible of being overthrown. When we feel sure
that our work will remain, that our representations of the
heavenly bodies are accurate . . . then we may quit this world
with the satisfaction of accomplished duty. "
¢ BILL SHEEHAN's love of Mars began before the Mariner 4
flyby in 1965 and has persevered into the Perseverance era.
He is author (with Jim Bell) of the modern classic, Discovering
Mars: A History of Observation and Exploration of the Red
Planet (University of Arizona Press, 2021).
32 DECEMBER 2023 * SKY & TELESCOPE
WILLIAM SHEEHAN
Sky & Telescope - December 2023

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