24 AUSTRALIAN SKY & TELESCOPE JULY 2016no question but that this nebulosity exists where
Herschel saw it.”
In closing, Barnard thrust a dagger at Roberts’
competence, reminding readers that it was “with the
same instruments described in his present paper
that Dr. Roberts failed to get any trace of the exterior
nebulosity of the Pleiades, which had been shown by
four observers with four different instruments not
only to exist, but to be not at all difficult objects.”
Moreover, Max Wolf at the University of Heidelberg
had recently taken a wide-field image of the same
Region 27 using Heidelberg’s new 40-cm astrograph.
The picture showed, with remarkable clarity, not only
the familiar Orion Nebula and the diffuse Horsehead
complex around Zeta Orionis, but also the feathery,
winding form of Barnard’s Loop.
Where, 15 years earlier, Isaac Roberts had
astounded astronomers with his breakthrough image
of the Andromeda Nebula, he was now confronted
with an equally vivid portrait of a celestial object
that he claimed wasn’t there. The Heidelberg 40-cm
was neither the “small toy” nor “child’s lantern-lens”
that Roberts had called Barnard’s instrument. And
Wolf’s exposure time of 6¼ hours eclipsed Roberts’
own 90-minute standard. (Wolf’s pièce de résistance
would come in 1911 with a 24-hour exposure of theAndromeda Nebula’s spectrum, accumulated over
twenty nights.)
Roberts offered the weak suggestion that both Wolf
and Barnard had targeted the wrong object! If not that,
then maybe the apparition on their plates had arisen
from atmospheric glare or reflections in the optics.
Had he accepted the verdict of his own eyes, he would
have recognised that a 90-minute exposure under
moist, semi-transparent English skies might indeed
be insufficient to capture a low-contrast space cloud,
especially when it overran the border of his plate. He
clung to the misconception that if he exposed long
enough to capture the faint stars William Herschel had
seen, then Herschel’s faint clouds should appear as well.
In fact, Barnard announced that he did see traces of
extended nebulosity on Roberts’ plates, a claim Roberts
himself denied.
The nebular feud ended abruptly with Isaac
Roberts’ death in 1904.
This episode is often remembered for how it
symbolised astronomy’s widening professional-
amateur divide around the turn of the 20th century.
But the real meaning is a bit different. Barnard, a
self-taught school dropout, was something of an über-
amateur himself. Rather, the skirmish and its outcome
reflected astronomy’s move toward professionalisation
and more rigorous scientific standards. In his drive to
become an effective researcher, Barnard aligned his
working methods and critical judgment to those of
university-trained astronomers. His knowledge base
was largely empirical, but it was structured effectively,
in a way one learns in the halls of academia. When
Barnard criticised Isaac Roberts for calcified thinking,
for not keeping up with the technical literature, and
for shrugging off big gaps in his knowledge, he was
enumerating the hallmarks of a poor scientist. That
Roberts was an amateur was not the issue.
Today, E. E. Barnard and Isaac Roberts are
invariably linked to the photographic catalogues
they bequeathed to astronomy. Despite Barnard’s
victory over Roberts in their long public feud, neither
catalogue stands higher than the other. Both are
examples of the era’s highest scientific artistry.
Image scale was the difference: where Barnard
portrayed the broad skylines of the galactic metropolis,
Roberts captured the façades of its notable individual
structures — two astronomers, no longer at odds, but
complementing each other. ✦Alan Hirshfeld is a professor of physics and a historian of
astronomy. His most recent book is Starlight Detectives:
How Astronomers, Inventors, and Eccentrics
Discovered the Modern Universe.ORION, HEAD
TO TOEThe vast
arc of Barnard’s
Loop encircles
Orion’sBeltand
Swordinthis
extremely deep
image stack taken
by Rogelio Bernal
Andreo. Amateurs
dominate wide-field
astrophotography
today.
ROGELIO BERNAL ANDREO / DEEPSKYCOLORS.COMAmateur vs Professional