75, 50 & 25 Years Ago Roger W. Sinnott
March-April 1939
Invisible Glass “The
amount of light
refl ected from a clean
glass surface is small;
if the refl ected light
could be entirely
eliminated the glass
would become invis-
ible.... The trick is
accomplished by coating the glass with a
thin transparent fi lm about ½ 00,00000,000 of an inch
thick....
“The thickness of the fi lm is critical. By
doubling its depth the eff ect can be com-
pletely reversed. The refl ections are intensi-
fi ed. Even this result may be of value, by
making possible more perfect refl ection from
a silvered or aluminized mirror surface....
“Astronomers have been struggling for
ages to get more of that precious commod-
ity, starlight, into its most useful place, and
every increase in effi ciency is welcome....
How far-reaching the new discovery will be
and to what new uses it may be put await for
the future to decide.”
While still a graduate student, soon-to-be
optical guru James G. Baker was reporting a
startling discovery just announced by research-
ers at MIT and General Electric. It led in just
a few years to the wide use of anti-refl ection
coatings on lenses and enhanced refl ectivity
coatings on mirrors.March 1964
Comet’s Demise?
“Dots [in the
accompanying
graph] represent
absolute magnitudes
of Encke’s comet
at each observed
return since 1786.... Smaller dots are
less accurate values. The curve fi tted by F. L.
Whipple predicts an increasingly rapid fad-
ing, leading to eventual disappearance about
Rey’s book. In practically no time at all I
could point out the major stars and planets
and knew where one constellation ended
and the next began. I even had a fi rm
enough grasp of the zodiac that I could
explain it to others when they saw me with
my telescope at night. I now unhesitat-
ingly recommend this book to anyone who
expresses an interest in learning about our
heavens. Thank you, Mr. H. A. Rey, and
bless you.
William Nopper
Rochester, New YorkWhat a pleasant surprise to fi nd Ann
Mulloy Ashmore’s article, “The Man Who
Illustrated the Heavens,” in the October
issue. I was fortunate to have a copy of
Rey’s book when I became a backyard
astronomer many years ago. His work
made it easy to locate and identify constel-
lations. Later, when I was a university stu-
dent, I could not help but wonder why the
professionals did not use his work to help
students fi nd their way around the sky.
Today, I recommend The Stars to anyone,
professional or student, who is interested
in astronomy. That the book can still be
found in most bookstores today is a testa-
ment to Rey’s genius. Again, great article
and thanks.
Ronnie Whitener
Murphy, North CarolinaMy eyes were misty while reading Ash-
more’s article about H. A. Rey, and not
from the drops the eye doctor had recently
put in, either: I teared up from the pure
joy I felt to see his story told to the world.
For me, H. A. Rey was a beloved teacher,
and without his book and its sensible
drawings, I would never have learned the
night sky. Thanks to Rey, I worried for
Boötes blowing smoke into the face of the
Bear. I located every pair of Ursa Major’s
paws. In my eyes, Hercules truly held
a raised club. When my college studies
called for a break, I would step outside
clutching my red fl ashlight and the
treasured book to savor the satisfaction of
successful searches. Soon, I was teaching
friends.
But I disagree that S&T’s adjust-
ments added clarity. In these versions
Cetus becomes a fl yswatter, Hercules aSkyandTelescope.com March 2014 9the year 1993.”
This bold prediction by a noted comet
expert did not come to pass. Last November,
with Comet ISON in its death dive near the
Sun, Comet Encke was a nice binocular target
at nearly 7th magnitude.March 1989
Remote Remnant
“Robert A. Fesen
(University of Colo-
rado) and colleagues
have recovered the
visible remains of
S Andromedae,
the fi rst supernova
ever recorded in an
external galaxy [in 1885]. The CCD image...
was taken in the light of an iron line at 3860
angstroms with the 4-meter refl ector atop
Kitt Peak. The long-sought remnant appears
as a dark spot... in absorption against M31’s
bright central region....
“The 1885 blast was a Type I supernova
that left behind an expanding cloud made
largely of iron. The debris is now about 0.
arc second, or about 1 light-year, across,
consistent with an expansion speed of 4,
to 5,000 kilometers per second since 1885.”
On August 17, 1885, a bright star appeared
in what was then called the Andromeda
Nebula. It reached 6th magnitude a few days
later and then faded slowly during the next
six months. Astronomers would not fi gure out
what a supernova was until the 20th century.Burmese dancing girl, and Sagittarius
a teapot. Although there is a traditional
way of visualizing the constellations,
those lines made little sense to me when
I was trying to learn the sky. I appreci-
ate your monthly charts, but to claim the
adjustments added clarity is nonsense.Let’s keep things simple for those who
will light the future, for they will decide
whether to light it with red fl ashlights or
porch lights.
Thanks for telling Rey’s story.
Barbara Blanko
Clinton, ConnecticutLtte layout.indd 9 12/23/13 11:37 AM