Sky & Telescope - January 2021 - 7

A Timely Observing Project
I was just studying S&T's wonderful
Laminated Moon Map and 350-piece
Moon Puzzle, along with Antonín
Rükl's fabulous Atlas of the Moon, to
ﬁnally learn the Moon well enough to
spend an hour or two casually observing
without constantly checking the map. I
came upon a feature I had never noticed
before: Palus Epidemiarum, the Marsh of
Epidemics. It's an irregularly shaped lava
plain in the Moon's southwest quadrant between and directly below Mare
Humorum and Mare Nubium. Palus
Epidemiarum includes craters Ramsden
and Capuanus, as well as Rimae Ramsden, Rima Hesiodus, and other interesting features. It's a busy area of the
Moon. Check it out!
P. J. Tramdack
New Castle, Pennsylvania

the founding of sky villages. Toward that
end, we are working to create a residential astronomy community where people
won't have to own property to live there.
Mirador Astronomy Village (miradorastrovillage.org) will include a cohousing community, apartments, a shared
house, and an RV park. Both full- and
part-time residents will have the opportunity to provide astronomy experiences
for our visitors and guests in exchange
for pay or reduced monthly rent.
David Oesper
Dodgeville, Wisconsin

I read the article while comparatively
viewing an image I captured of M8 from
my humble 5.5-inch (140-mm) SchmidtNewtonian Comet Catcher. I wish that
I'd been able to read it while that image
was stacking live onscreen. My ﬁrst
priority is to reread the article with the
Lagoon Nebula above me.
Thank you so much for the effort
and the art that brought M8 back into
my heart and soul.
Gary Shaw
Auburn, Maine

FOR THE RECORD

We Love the Lagoon!

* In "Observing Geosat Flares" (S&T: Oct.

I want to thank you for Howard Banich's "Swimmin' in the Lagoon" (S&T:
Aug. 2020, p. 20). It's the most engaging
writing about astronomy I've ever read.
Well, perhaps some of Timothy Ferris's
metaphoric paragraphs come close.

2020, p. 40), the correct direction of travel of
the anti-solar point at night is east to west.

* "Mars at its Most Magnificent" (S&T: Oct.
2020, p. 47) should state that asteroid 8
Flora will be 130,000,000 km (80,778,255
miles) from Earth on October 31st.

Residential Sky Village
In "It Takes a Village" (S&T: Oct. 2020,
p. 84), Christopher Smythies encourages

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

1971

1996

January 1946
Plastic Lenses? "Optical plastics have been developed almost
entirely under the impetus of
wartime necessity; the story . . .
has now been released . . . For the
Army, a plastic 3-power anti-tank
telescope with a 6-inch eye relief
and 1-inch exit pupil proved a
boon possible of immediate production in large quantity. . . .
"These optical plastics
researches have been carried out
under . . . Dr. Theodore Dunham,
Jr., on leave from Mount Wilson
Observatory. Although elements
of plastic cannot be used for the
precision required in astronomical
instruments, the future may bring
further improvements . . ."
Since they can be mass produced from a mold, plastic lenses
have found wide use for eyeglasses
and some low-cost camera lenses.
But plastic scratches easily and
changes with age. In large telescopes, glass is still king.

January 1971
X-ray Frontier "Early in 1960,
rocket scientists at the U. S. Naval
Research Laboratory obtained
the first X-ray picture of the sun.
. . . Now more than 40 discrete
sources of celestial X-rays are
known, as well as a diffuse X-ray
background that covers the sky
almost uniformly. . . .
"[But with] the first Small
Astronomy Satellite (SAS-A)
scheduled for launching December
12, 1970, [astronomers] expect to
find hundreds of additional X-ray
sources . . . The measurements of
known and new X-ray sources are
to include position, intensity, energy
spectrum, and variations in strength
from minutes to months."
Renamed Uhuru once in orbit,
this highly successful mission truly
launched X-ray astronomy.
January 1996
Alien Eavesdroppers "Can
spacecraft discern the existence
of an intelligent civilization on
our planet? From close range

it's rather easy: reconnaissance
satellites routinely spot all manner
of structures and city lights from
orbit. But distant spacecraft have
to use less direct means. . . .
"NASA's Wind spacecraft . . .
carries instruments for monitoring
the solar wind [and one] detector,
called Waves, [and] is sensitive
to radio emissions [at] shortwave
bands from 1 to 14 megahertz
(MHz). [Signals from Earth] are
most obvious when the spacecraft
looks down on the planet's nighttime hemisphere [and they] leak
outward into space.
"The spacecraft records a
cacophony of transmissions at each
wavelength. But a specific station
can be identified if its broadcast
occurs at an otherwise quiet time
. . . Waves and its 15-meter-long
antennas could detect Earth's radio
broadcasts only as far away as the
asteroid belt. By contrast, our strongest signals, from the phased-array
radars of ballistic-missile warning
systems, carry for many light-years
across interstellar space."

sk yandtelescope.org * JANUARY 2 021

http://www.miradorastrovillage.org http://www.miradorastrovillage.org http://www.skyandtelescope.org

Sky & Telescope - January 2021

Table of Contents for the Digital Edition of Sky & Telescope - January 2021