Sky and Telescope - June 2017 - 37

"The dark part of the Moon in the syzygies" refers to
Earthshine inside the crescent near the time of new Moon.
But the last bit deserves to be given in its original French - il
semble que son centre soit un peu moins terne que le reste
de sa surface - because "un peu moins terne" could mean
either "a little less dull," meaning brighter, or "a little less
of the dullness," meaning dimmer! If the latter, we have the
important result that Darquier was the ﬁrst astronomer to
notice that the nebula has the form of a faint ring.
Regardless, the primary sources make clear that all the
books have the priority backward: Messier observed M57 ﬁrst,
on January 31, 1779, while Darquier did not even know about
Bode's Comet and did not scan the sky near its path until
after February 9th.

Discovering vs. "Discovering"

nebula located between the two beautiful stars β & γ Lyrae; it is
very dim, but with a sharp boundary . . . one ﬁnds its position
determined in my catalogue.

Darquier does not give a precise date, but it cannot be
earlier than February 10th. He was incredulous that such
an object could be previously unknown, and he offered the
(incorrect) theory that perhaps it had only recently appeared:
If one considers that this nebula, which is located between
two beautiful stars, which are very close to each other and
can pass at the same time in the same telescope ﬁeld, and to
which astronomers had often turned their instruments, there
is reason to be astonished that we have not spoken about it; it
must also be admitted that it takes a rather powerful telescope
to perceive it: Might this be a new production of nature?

Darquier's Meaning
In 1782 Darquier reprinted his 1779 letter to Messier in a
compilation titled Observations Astronomiques, Faites a Toulouse, par M. Darquier. . . Deuxieme partie. At the end he added
an additional remark about the nebula in Lyra:
This nebula has not been noticed, at least as far as I know, by
any astronomer; one cannot perceive it except with a powerful
telescope. It does not resemble any other known: it is as large as
Jupiter, perfectly round and sharply bordered; dull like the dark
part of the Moon in the syzygies; it seems that its center is a
little less dull than the rest of its surface.

So why did Messier, in his catalog, wrongly hand away the
honor of discovery to another? The answer, pretty clearly, is
that he didn't. We seem to have a case of language creep.
"M. Darquier in Toulouse discovered this nebula, while
observing the same Comet" sounds to us like a ﬂat statement that Darquier was ﬁrst to see M57. But "discover"
may also mean simply to discern or spot something, a
usage that was more common in the 18th century and has
since become almost obsolete. And commas back then were
thrown into sentences in ways they aren't now. In modern
terms, think "Darquier spotted this nebula while observing
the same comet."
Or possibly Messier was using "discover" the way we do
but meant Darquier's later, independent discovery.
Either usage matches Messier's statements that he himself
"discovered" Bode's Comet on January 19th, though by the
time he wrote that in his 1779 memoir and later in his catalog, he and every other astronomer knew that Bode was the
ﬁrst. There's no question about this; in his memoir Messier
reprints two German articles describing how Bode in Berlin
had ﬁrst spotted the comet on the evening of January 6th.
Moreover, Messier's chart of the comet's path begins in
Vulpecula with Bode's observations plotted as a dotted line
with its start labelled "at Berlin on January 6." The path marks
the positions observed by Messier along a solid line continuing from a point that he labelled, "Discovered at Paris."
So "discovered" for M57 should likewise be read with Messier's slightly antique meaning. In any case, primary sources
prove without a doubt that Messier was the ﬁrst to sight M57.
¢ DON OLSON, author of Celestial Sleuth (2014) and the forthcoming Celestial Sleuth: Further Adventures (2018), teaches
physics and astronomy at Texas State University.
¢ GIOVANNI MARIA CAGLIERIS, of the Milan Amateur Astronomers Club (Circolo Astroﬁli di Milano), has interests in
visual observing and the history of astronomy.

The authors are grateful for research assistance from
Margaret Vaverek at Texas State University's Alkek Library.
s k y a n d t e l e s c o p e .c o m

* JUNE 2017

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