Sky & Telescope - March 2025 - 7

of a single event - it is the multiple
of probability and potential damage.
The DART mission was a triumphant
proof-of-concept for planetary defense.
But the only way to reduce the risk of
a catastrophic impact is to prepare in
advance for the worst-case scenario,
even though it might never happen.
Currently we do not have such a
policy. Therefore, I submit, we humans
are creating a greater risk than any
unknown impactor is, since we are
fully capable of rendering a large object
harmless with the proper infrastructure
and yet are ignoring the need to
develop a plan to do so.
Joel Marks
Milford, Connecticut
To Each Their Own Color
Mathew Wedel's " Star Crossed " (S&T:
Oct. 2024, p. 43) is a great binocular
highlight. I have trouble discerning the
color of TX Piscium in my 7×50 binoculars,
but it's a well-balanced challenge.
To my eyes, it's a very reddened orange
at 51× in my 12.5-inch scope. The chart
scale used by the article was perfect.
Thank you, Sky & Telescope, for your
continued good work with this, the
most helpful Comet Tsuchinshan-Atlas
article, and your many observing and
photographic articles.
Ted Harp
Tuttle, Oklahoma
"
Mathew Wedel replies: Thank you
for the kind words! I find the colors
of stars are more intense in smaller instruments.
In a 12-inch Dobsonian even the
carbon stars are brightened up to maybe
orange at best.
But then I'm always amazed at how
color perception of stars varies among
observers - another prod, if any were
needed, for everyone to get out and see
these things for themselves.
Reaching for the Stars
Corey Burrell is a star! It's wonderful
that he shared his passion for stargazing
with the readers of Sky & Telescope
in " The Gift of Stargazing " (S&T:
Oct. 2024, p. 84)!
I once read a book (a true story)
about a family whose parents were so
poor that the father would give his
children each a star on their birthday.
And, when I read that his parents gave
him a telescope for his 7th birthday, I
thought, How great is that! With their
love, he could see Mars and Jupiter.
I can feel that his dream of visiting
Zion National Park, Bryce Canyon, and
Monument Valley will happen soon.
After all, " One shouldn't go through
life without visiting them! " to observe
the night sky.
Caroline Robicheaux
Patchogue, New York
SUBMISSIONS: Write to Sky & Telescope, 1374 Massachusetts Ave., 4th Floor, Cambridge, MA 02138, USA, or email:
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75, 50 & 25 YEARS AGO by Roger W. Sinnott
1950
1975
 March 1950
Remote World " [Seemingly] Pluto
is a much larger body than the
moon or Mercury. According to the
best evidence available, the mass of
Pluto is 0.9 or 0.8 times the mass of
the earth . . . One would expect that
such a body would have an atmosphere.
Since a dense atmosphere
would correspond to a high albedo,
it cannot have a dense atmosphere.
It is impossible to account for the
faintness of Pluto except by making
it almost black. . . .
" In view of the apparent absence
2000
of an appreciable atmosphere,
. . . it is important to ask with what
degree of certainty the mass of
Pluto has been determined. "
Yale astronomer Dirk Brouwer
already suspected flawed data. Now
known to be much smaller, Pluto
was reclassified as a dwarf planet.
 March 1975
Winking Star " On the evening of
[January] 23rd, Eros passed directly
over the 3.6-magnitude star Kappa
Geminorum - the first case in history
of a well-observed occultation
of a star by an asteroid. [Along with]
three positive observations [from
Massachusetts,] six more and perhaps
a seventh have been reported
from Connecticut. . . .
" [Near] Avon, Connecticut, Dr. D.
R. Morrison was not thinking of the
occultation, but was endeavoring to
locate Eros with 8 x 42 binoculars.
He was startled to see Kappa Geminorum
suddenly and completely
vanish, and return just as abruptly
about two seconds later. . . .
" Since Eros was at minimum
brightness in its rotational cycle . . .
it was presenting its smallest cross
section . . . Tentatively, the occultation
results indicate a diameter of
about 14 miles . . . "
 March 2000
Silent Menace " The Sun's sometimes
deleterious effect upon our
technology is an old story that
begins with the invention of the
telegraph and telephone. Electrical
currents induced during geomagnetic
storms in the 19th century
were at times so powerful that
telegraphers often didn't need
battery power to send their dits
and dahs down the line. . . .
" Like telephone wires, power
lines make excellent conductors
for the currents created by geomagnetic
storms - after all, power
lines are supposed to carry electric
current. The problem is that
the storms produce direct current
(DC) while the lines are meant to
carry alternating current. Induced
DC loads cause the windings of
transformers to overheat; insulation
can then break down and
transformers fail . . . On August 2,
1972, a 230,000-volt transformer
in British Columbia exploded. Near
the peak of the last sunspot cycle
on March 13, 1989, the HydroQuebec
power grid failed, plunging
large portions of Quebec into
darkness for nine hours. "
Sten Odenwald worried that we
are now less prepared than ever
for such catastrophes.
sk yand tele scope .o r g * MARCH 2025
7

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