My first Magazine Sky & Telescope - 03.2019 | Page 54

MARCH 2019 OBSERVING
Exploring the Solar System by Thomas A. Dobbins
Expectation
and Observation
Amateurs can benefi t greatly by
approaching the eyepiece without
preconceived notions.
E
52
M A RCH 2 019 • SK Y & TELESCOPE
tion, complained about the lingering
effects of the Martian canal debate:
The careful observers with better
telescopes who continued to denounce
the “canals” as optical illusions were
castigated. This controversy brought
disrepute to planetary science and
weakened its status in universities.
To this day the effects have not been
overcome and affect even the NASA
programs adversely through inadequate
academic scientifi c support.
Kuiper went on to attribute the
longevity of the canals myth to a
perverse rating system that emerged
among the amateur community of
Mars observers during the 1920s:
[I]t is instructive to see how the cult
was perpetuated in semi-professional
literature for decades. For many
years W. H. Pickering, the brother
of the famous Harvard astronomer
E. C. Pickering, collected amateur
observations of Martian canals and
published the results in 44 reports in
Popular Astronomy. The amateur
observers were “rated” by the number
of “canals” they had noted. Thus, there
was a premium on reporting many
canals.
p The presence of radial “spokes” like those
in the left ansa of Saturn’s rings in this Voyager
2 image (top) were seen and sketched years
earlier by Stephen James O’Meara (above).
The notion that under good atmo-
spheric conditions any observer worth
his salt and equipped with a decent
telescope should be able to see canals
on Mars persisted well into the 1960s.
The Cave Optical Company’s 1962
catalog enticed prospective customers
with the claim that “Mars is seen in
a wealth of very fi ne maria and canal
detail” through the fi rm’s 10-inch
Astrola refl ectors. Readers of the 1964
Optical Craftsmen telescope catalog
were assured that “much of the subtle
canal network of Mars can be observed
at favorable oppositions” using their
8-inch “Connoisseur Series” telescope.
JA
ven as the 20th century drew to
a close, visual observers of the
planets continued to make unex-
pected discoveries. Two sterling
examples were the work of Stephen
James O’Meara.
In 1976 O’Meara reported the
presence of dusky radial “spokes” in
Saturn’s B ring — delicate, ephemeral
features that had been independently
recorded in 1887 by Thomas Gwyn
Elger in England and Charles-Émile
Stuyvaert in Belgium. Five years later,
O’Meara was able to determine an
accurate rotation period of features
in the temperate latitudes of distant
Uranus (S&T: Sept. 2012, p. 54).
These remarkable feats of visual
acuity, both accomplished using a
surprisingly modest aperture (the
9-inch Clark refractor at the Har-
vard-Smithsonian Center for Astro-
physics), were initially greeted with
skepticism and even derision. The
credibility of visual observers had
been irreparably damaged early in the
20th century by the bitter debate that
raged for decades over the presence of
canals on Mars.
In a 1967 address to the Arizona
Academy of Sciences, Gerard Kuiper
(1905–1973), the leading American
planetary scientist of his genera-