Sky & Telescope - May 2021 - 7

compass lights off, and was steering
southeast by the stars. Then, I saw a
large ship heading toward my port side;
I could see its red bow light. I was now
on alert for a converging course.
I could tell that it was getting closer
because the red bow light was rising
higher. Then, I began to see stars under
the light. I ﬁ nally ﬁgured out that it
wasn't a ship but Mars! It was so red!
I never had to change course to avoid
that collision.
We continued sailing using celestial
navigation and eventually found the
island Jost Van Dyke and then Tortola.
Ray Locke
Venice, Florida

Geminids in the City
I was glad to see the Geminids receive
the recognition they deserve in " Get
Ready for the Geminids " by Joe Rao
(S&T: Dec. 2020, p. 14). For the past
couple of decades, I've considered them
the year's best meteor shower. I've never

had very good luck with the Perseids,
and even the Leonids of the early 2000s
were in my opinion somewhat lacking,
since I apparently missed the peak due
to poor planning.
However, the Geminid meteor
shower of 1994 was truly memorable.
At the time, I was collecting data for
my PhD dissertation, imaging Seyfert
galaxies and quasars with a 24-inch
(0.61-meter) telescope on a rooftop on
the University of California, Los Angeles campus in the middle of some of
the worst light pollution modern cities
have to offer. The equipment, an optical
CCD camera and a liquid-nitrogencooled infrared CCD camera (that was
made on campus), easily pulled signals
out of the murk. Visually, I struggled to
make out 2nd-magnitude stars!
During exposures, I'd leave the
dome and stroll around the roof. I

1971

1996

Brant Nelson
Ayer, Massachusetts

FOR THE RECORD

* PuWe 1 is not the largest known planetary nebula, as stated in " Springtime Blossoms " (S&T: Mar. 2021, p. 63), but it is one
of the largest planetaries known.

* The table in " Catching Celestial Butterflies " (S&T: Feb. 2021, p. 18) should have
stated that M76 lies at +51° 34'.

SUBMISSIONS: Write to Sky & Telescope, One Alewife Center, Suite 300B, Cambridge, MA 02140, USA or email:
letters@skyandtelescope.org. Please limit your comments to 250 words; letters may be edited for brevity and clarity.

75, 50 & 25 YEARS AGO by Roger W. Sinnott
1946

wasn't expecting much that night.
However, I was astounded to see these
bright tears that just kept coming!
Every minute or two, another pleasingly bright one would slowly streak
through the mostly featureless sky. Of
course, I couldn't help but think about
how many I wasn't seeing - it must
have been spectacular away from the
city. Yet it far surpassed any meteor
shower I'd seen before or since.

May 1946
Chirp, Chirp " Professor E. B.
Frost [was] director of the Yerkes Observatory from 1905 until
1932. In his later years he was
blind, yet carried on some of his
own correspondence, printing in
capital letters on a narrow ribbon
of paper. At the end, he signed
himself, 'E. B. Frost, IPSE.' I knew
him for only a little while but I shall
never forget his telling me about
Dolbear's formula.
" In the middle of the night,
when a cricket in the dome is your
only companion, count the number
of chirps in 15 seconds, add 40
to it, and the result will be the
temperature, Fahrenheit. . . . This
is Dolbear's formula. . . . I don't
know who Dolbear was or what he
did. [But] I've used his formula and
it usually works. "
Roy K. Marshall wrote this for
the column Astronomical Anecdotes. (For those whose Latin is
rusty, " ipse " means " himself. " )

May 1971
Dimmer Skies " The extinction
coefﬁcient is the loss in magnitudes of a star's light at the zenith,
in clear-sky conditions. . . .
" A group of University of Washington astronomers, in a study
called Project Astra, is compiling
present and past measurements of
extinction, made at observatories in
all parts of the world, to study the
long-range changes in the earth's
atmosphere caused by man-made
pollution. One of the first results is
a comparison of the extinction at
Mount Wilson Observatory at two
epochs half a century apart . . .
" Over the 50-year interval, the
extinction coefficient increased by
0.27 magnitude at a wavelength
of 3500 angstroms (ultraviolet), by
0.09 magnitude at 4400 (blue), and
0.10 magnitude at 5500 (yellow).
'These are large differences,' notes
[project chair Paul W.] Hodge . . .
'We came to realize [that astronomical extinction methods] far surpass
in accuracy the existing equipment
used in air pollution studies.' "

May 1996
Hubble Deep Field " [For] 10
consecutive days beginning last
December 18th, [the Hubble
Space Telescope] directed its gaze
to a nondescript field near the Big
Dipper's handle. . . .
" The resulting montage was
unveiled to an eager gathering of
astronomers and journalists on
January 15th. [Space Telescope
Science Institute director Robert] Williams announced that the
results were 'all that we could
have hoped for.' [The Hubble
Deep Field] contains over 1,500
galaxies, some as faint as 30th
magnitude . . . And they all lie in
a patch of sky no larger than that
covered by a grain of sand held at
arm's length. This implies that over
50 billion galaxies now lie within
humanity's grasp. "
Since then, other tiny ﬁelds
have been imaged even more
deeply by the Hubble Space
Telescope. The goal is to see what
galaxies looked like as soon after
the Big Bang as possible.
s k y a n d t e l e s c o p e . o r g * M AY 2 0 2 1

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Sky & Telescope - May 2021

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