Sky & Telescope - August 2020 - 7

also utilized dead reckoning, relying on a
sledge odometer to determine the distance
they traveled from a previous location, to
calculate his latitude without clear weather.
Scott also had a sledge odometer, but it
would clog with snow. When both reached
the pole, they crisscrossed the area, making
determinations of latitude to calculate where
each believed the true mathematical pole
lay. Both of their best determinations were
off from the true pole.

I enjoyed reading about Captain Cook's
use and knowledge of celestial navigation and the accuracy of his measurements. The telescopic quadrant, while
providing better accuracy to its users,
was an expensive instrument compared
to the more basic octant, which was
more affordable. This simpler instrument used a small pinhole peepsight,
called a sighting pinnula, which would
have produced less accurate results.
Aldo Cugnini
Long Valley, New Jersey

Starlink and the Stars
Monica Young (S&T: Mar. 2020, p. 14)
provides the well-thought-out details on
the potential impact of so many satellites at operational altitudes near 340
and 550 km (210 and 340 miles).
While astronomers pay attention
to what's in the sky, birds actually
need the stars to successfully navigate
during nighttime migrations, some of
which are thousands of miles long and
under skies in which the new interlopers are very visible.
Terry Herlihy
Chicago, Illinois

1970

1995

Joe Kubovcik
Clayton, Delaware

I really like the new modern look and
feel of the S&T website. It's easy on the
eyes, and I don't need a Telrad to ﬁnd
my way around! The info bar at the top
was a nice touch as well. Thank you
again for being my absolute go-to place
for all things astronomy!
Randall Kayfes
Tucson, Arizona

Compliments on Design
I've been a faithful reader of S&T for
many years and still have many older
issues. My earliest dates back to 1968.
I like the changes made, even though
I'm still partial to the original sky

FOR THE RECORD

* On asteroid Ryugu (S&T: May 2020, p.
17), the startlingly large crater left by Hayabusa 2's projectile was a result of the rocks'
low density and the asteroid's weak gravity.

SUBMISSIONS: Write to Sky & Telescope, One Alewife Center, Cambridge, MA 02140, USA or email: letters@
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75, 50 & 25 YEARS AGO by Roger W. Sinnott
1945

charts. Anyway, I was really impressed
with the cover of the March issue -
wow! Beautiful Carina Nebula! Keep
up the great work.

August 1945
Dimmed Moon "[There] was an
87 per cent eclipse of the moon on
June 25-26, visible in the Pacific
and Indian Oceans, Asia, Australia, and in the regions where most
of the fighting now continues. An
Associated Press dispatch reports
that three American destroyers were
being attacked that night by a dozen
enemy planes. Bright moonlight
made the surface vessels easy
targets, but when the partial eclipse
darkened the moon's light the
attack was successfully repulsed.
"Meanwhile, Pfc. William W.
Thorp, of Boston, now on Okinawa,
was concerned with sporadic air
attacks while observing the partial
eclipse. The next day he made a
series of sketches from memory,
showing that at midnight, Okinawa
time, the eclipse reached its maximum, when 'it looked like a dark ball
with an icecap directly on top.'. . .
"'Scattered clouds were in
evidence, but not heavy enough

to obliterate vision. Smoke from
screening blew across with varying intensity, but it only gave a
foglike effect.'"
August 1970
Oxygen for Life "[A] theoretical
discussion by Wallace S. Broecker,
Columbia University, . . . considers the balance between oxygen
produced by plant photosynthesis and that used up by animals
and bacteria, including also what
would result if man burned all
known reserves of fossil fuels. In
this most improbable event, less
than three percent of the available
O2 would be used. . . .
"By similar calculations, Dr.
Broecker finds that the oceans are
also relatively safe from O2 depletion . . . He concludes: 'If man's
existence is to be threatened by
pollution of the environment he will
succumb to some other fate long
before his oxygen supply is seriously depleted. . . . Hopefully the
popular press will bury the bogeyman it created.'"

Researchers today are less conﬁdent. Global warming makes the
oceans less able to absorb atmospheric oxygen. And there are new
worries over deforestation.
August 1995
Cosmic Cigar "In August 1994 the
asteroid 1620 Geographos cruised
5.1 million kilometers from Earth
. . . Eagerly awaiting the flyby was
Steven J. Ostro (Jet Propulsion
Laboratory), who used the Goldstone 70-meter tracking antenna
in California to bounce a 450-kilowatt beam of radio energy off the
interplanetary interloper. . . .
"Geographos has indeed
proved to be an oddball. 'The
silhouette is irregular, nonconvex,
and has an aspect ratio of 2.76
± 0.21,' [Ostro's team reported],
'establishing [Geographos] as
the most elongated solar-system
object yet imaged.' It is also somewhat larger than expected,"
Even more elongated is the
interstellar visitor 'Oumuamua,
discovered in 2017.

sk yandtelescope.org * AUGUST 2 02 0

http://www.skyandtelescope.org

Sky & Telescope - August 2020

Table of Contents for the Digital Edition of Sky & Telescope - August 2020