Sky and Telescope - February 2017 - 8

From Our Readers

Of Mars and Memory Lane
I enjoyed Camille Carlisle's ExoMars
article so much (S&T: Oct. 2016, p. 22)
that several days later I read it again.
What caught my eye, in addition to the
mission's objectives, was her wording
"pretty pickle." That's an expression I
heard often in my youth - but not at
all in recent years. Seeing it sent me far
back in time for a moment. Back then
there was still a debate about canals
and civilization, and galaxies were still
called "extra-galactic nebulae." Memory
lane is fun sometimes, especially when
part of new science.
Darryl Davis
Albany, Oregon

Raﬀerty on Ritchey
I have never read an astronomy-related
article that has had such a deep impact
on me as Ted Rafferty's (S&T: Oct. 2016,
p. 66). I had very little knowledge of
George Ritchey's life story. However, I
did realize how much bearing the great

Ritchey-Chrétien design now has on
modern astronomical optical systems.
Rafferty did an amazing job conveying this, and I look forward to seeing
Ritchey's 40-inch telescope later this
year during our family vacation in Flagstaff, Arizona.
Tyler Welch
Beaver Dam, Wisconsin

Rükl's First Lunar Atlas
Readers might like to know that Antonin Rükl's Atlas of the Moon (S&T: Nov.
2016, p. 14) was ﬁrst published in 1976
by Artia Publishing in Prague. Its English-language edition, which I bought
in September 1978, is titled A Concise
Guide in Colour: Moon, Mars and Venus.
Six beautiful maps of Mars are included
as a bonus - yet the book's covers do
not mention the author's name! It's still
available now and then; do a browser

1967

1992

Peter Gibbons
Cork, Ireland

FOR THE RECORD

* The globular cluster pictured in Corona
Australis (S&T: Aug. 2016, p. 76, and
Nov. 2016, p. 75) is NGC 6723, not NGC
6541.
* In the illustration showing Schiaparelli's landing sequence (S&T: Oct. 2016,
p. 23), the final two altitudes should be 2
m and 0 m.
* Isaac Roberts took his historic image
of asteroid 80 Sappho (S&T: Oct. 2016,
p. 6) on January 14, 1887.

SUBMISSIONS: Write to Sky & Telescope, 90 Sherman St., Cambridge, MA 02140-3264, U.S.A.

or email: letters@skyandtelescope.com. Please limit your comments to 250 words.

75, 50 & 25
7
5 YEARS
YEAR AGO by Roger W. Sinnott
1942

search for ISBN 0-600-36219-1.
By the way, concerning the photograph of the late Leif Robinson's ofﬁce
(S&T: Nov. 2016, p. 26), I have to ask:
Was there an earthquake that day? A
burglary perhaps?

February 1942
Demon Star "Jesse A. Fitzpatrick,
who compiles our Observer's Page,
sent us times for the minima of [the
well-known variable star] Algol in
January that were a continuation of
those published in The Observer's
Handbook last year. [But in] connection with his article on Algol in
this issue, Dr. Zdenek Kopal gave
us a schedule of February minima
which agreed neither with Mr. Fitzpatrick nor with the Handbook. . . .
"Adding Joseph Ashbrook's 25
minutes to Dr. Kopal's 8:00 p.m. for
the January 1st minimum gives 8:25
p.m., or just the time Mr. Fitzpatrick
refers to in his letter to us . . . ."
Unexpected (if subtle) changes
in this eclipsing binary's period
had been known for a century.
Joe Ashbrook, then a young grad
student in astronomy, was among
those who caught this latest one.
He joined the Sky & Telescope staff
in 1953 and went on to become the
magazine's editor in 1964.

F E B R U A R Y 2 0 1 7 * SK Y & TELESCOPE

February 1967
Saturn's Brood "Has a tenth satellite of Saturn been discovered? A
preliminary announcement of such
an object has come from France
. . . If the case is substantiated,
this will be the first addition to that
planet's retinue of moons since
Phoebe in 1898 (not counting the
never-confirmed finding of Themis
by W. H. Pickering in 1905).
"The discovery was made photographically by Audouin Dollfus, wellknown planetary and lunar specialist of Meudon Observatory . . .
"Dr. Dollfus described the new
object as of magnitude 14, and as
moving just outside the rings . . .
with a period of 18 hours."
Dollfus's ﬁnd was conﬁrmed
at other observatories and soon
named Janus, but not all the
images gave a unique revolution
period. The confusion was not
cleared up until Saturn's rings were
again edgewise to our view, in
1979-80: another new moon, later
named Epimetheus, and Janus
travel in much the same orbit.

February 1992
Geminga "Powerful new observatories almost always solve longstanding astronomical mysteries.
But in at least one case the Compton Gamma Ray Observatory, in
orbit since last April, seems to have
done the opposite.
"Several years ago, after a
20-year effort, astronomers finally
thought they had linked the gammaray source known as Geminga to
an optical and X-ray counterpart
[and] inferred that the object is an
isolated neutron star. . . . Yet when
the Compton Observatory [examined] the oddball source, it captured
gamma rays only at the very highest
energies. . . . How could one source
emit light, X-rays, and high-energy
gamma rays but remain 'dark' in
spectral windows in between?"
Geminga turned out to be an
unusual pulsar (rapidly rotating neutron star). Its 0.237-second pulses
are mainly seen with gamma- and
X-ray satellites, but only weakly with
ground-based radio telescopes. It's
normally the other way around.

Sky and Telescope - February 2017

Table of Contents for the Digital Edition of Sky and Telescope - February 2017