Sky & Telescope - August 2019 - 6

FROM OUR READERS

Last Look from Yerkes?

p Al Bellg got a look
through the 40-inch
refractor at Yerkes Observatory on September 26, 2018, the last
clear night for public
observation.

Research and You Will Find

As a mutual 65th birthday present, my childhood astronomy
buddy Al Bellg arranged for the two of us to tour and view
at the 40-inch refractor at Yerkes Observatory in Williams
Bay, Wisconsin. It turned out to be the very last clear night
for public observation before the observatory ceased public
operations. We brought our own 40-mm and 50-mm eyepieces to view Saturn and the Saturn Nebula, and we used
the focuser ourselves.
While driving home, we remarked on how simple that
giant scope was to operate: It uses setting circles, and the
process of ﬁnding objects is totally manual. We were tickled
to watch our host, a graduate student in astronomy at the
University of Chicago, grasp the wooden handlebars and
swing around the monstrous but ﬁnely counterbalanced
tube to center objects for viewing, using a 6-inch ﬁnder.
Wouldn't amateur astronomy clubs line up for a series
of "rental" nights to use the scope? Could management of
Yerkes Observatory be shared by a consortium of amateur
groups, perhaps with a local college physics department
(there are two within 35 miles) keeping the keys and instituting a training program for representatives of the participating clubs? We'd love to see it happen!
Steve Marshall * Milwaukee, Wisconsin

The letter titled "Problems at Home"
(S&T: May 2019, p. 6) expressed concern
that money is wasted on space exploration and, in particular, SETI research,
which the writer believes "have little
value or relevance to Earth and its
inhabitants. . . ." I strongly disagree.
During ﬁscal year 2018, the U.S.
federal government spent around $4.1
trillion. Less than half of one percent of
that went to NASA and essentially zero
to the SETI Institute, an organization
funded mainly by private contributions.
Space research has already yielded vast
tangible beneﬁts. Can you imagine
going back to a world without GPS, telecommunications, or weather satellites?
Finding even bacterial extraterrestrial
life would be an astounding scientiﬁc
breakthrough; ﬁnding intelligent extraterrestrial life would be the greatest
discovery in the history of humanity.
That letter reminded me to make a
donation to the SETI Institute.
Bruce Flamm
Riverside, California

You may have gotten this question
many times previously, but please
explain again: Referring to the planetary almanac (S&T: May 2019, p. 44,
for example), why does the path of the
ecliptic appear to be sinusoidal? Does
the projection or development of the
path of the ecliptic from the surface of
the celestial sphere onto the plane of
the paper result in this geometry?
William Woods
Weyers Cave, Virginia

Roger Sinnott replies: Both the
celestial equator and the ecliptic are
great circles. But, as you note, distortion
occurs in the rectangular projection when
a spherical surface is ﬂattened out onto a
sheet of paper. If the equator is made to be
a straight line, the ecliptic becomes roughly
sinusoidal. It would also be possible to plot
the ecliptic as a straight line, but then the
equator would become sinusoidal.
There is another type of projection,
the gnomonic, in which all great circles
are straight lines. But in this case there

AUGU S T 2 019 * SK Y & TELESCOPE

is extreme distortion in scale across the
chart, and less than one hemisphere can be
shown on a gnomonic map. It is, however,
preferred by those who observe and plot
meteor showers. Each meteor's track is
simply a straight line.

All's Well with Caldwells
As we approach the 25th anniversary
of the Caldwell catalogue, I'd like to
take a moment to thank a small but
vocal group of curmudgeons for their
whirlwind of negative publicity that has
only helped vault the Caldwell objects
into mainstream use. The Astronomical
League's Caldwell Observing Program
is thriving. Astronomy apps and Go To
databases identify Caldwells by default.
The public requests target views by "C"
number at outreach events. Even the
redoubtable Wikipedia highlights Sir
Patrick's gems. Quite an impressive run
for a list of post-Messier suggestions
that started as a single Sky & Telescope
article (Dec. 1995, p. 38).
Stephen Saber
Rock Island, Illinois

More Optical Mishaps
Bill Dellinges's letter (S&T: June 2019,
p. 9) reminded me of a time when I
imaged the crystal-clear sky all night
with Amherst College's 18-inch Clark
refractor. As dawn approached and I
enthusiastically gathered up my plates
for development, I couldn't ﬁnd the lens
cap anywhere. Eventually I located it
perched safely atop the telescope's tube.
After throwing away the undeveloped plates, I headed home.
Harold Heaton
Damascus, Maryland

In winter, my favorite ﬁrst look after
collimating my 12.5-inch truss Dob is
the Double Cluster, where I view the
small semicircle of stars a friend has
coined the "Cowboy Asterism" (the
semicircle is his head, and the bright
star beneath it is the medallion in his
string tie). One night I had the hardest time picking out the asterism. I ﬁrst
thought perhaps transparency was worse
than it appeared, then I began to wonder
if something was wrong with my eyes.

COURTESY OF STE V E M A RSH A LL A ND A L BELLG

Sinusoidal Tendencies

Sky & Telescope - August 2019

Table of Contents for the Digital Edition of Sky & Telescope - August 2019