ºJanuary 1945
Spurious Perspective “In the
Adler Planetarium there is a mag-
nifi cent large model of the moon;
when it is viewed from a distance
of 20 to 30 feet, something about
it appears very different from a
telescopic view, and it must be
[an] effect of spurious perspec-
tive involuntarily experienced in
telescopic views.
“All of this emphasizes the
foolishness of [asking], ‘How far
away does this telescope make the
moon appear to be?’ The answer to
this question should be a polite but
fi rm insistence that the telescope
does not make the moon appear
nearer; the perspective is all wrong.
The only thing the telescope does
is to magnify the naked-eye image
of the moon. Talk about magnifying
powers of 10,000 diameters to be
used on the 200-inch telescope,
‘thus bringing the moon up to only
24 miles from the earth,’ is prob-
ably the maximum in telescoptical
absurdity....
“Unless astronomers assign
themselves the task of stopping
journalistic nonsense about astron-
omy, surely no one else is going to
do the job.”
Longtime columnist Roy K. Mar-
shall was very much the “Science
Guy” of his time.ºJanuary 1970
Pulsar Periods “‘Continuing
observations of the times of arrival
of the radio pulses from the pulsars
visible from Jodrell Bank indicate
that almost all [have rotation rates
that are slowing down],’ reports the
British radio astronomer G. C. Hunt
in Nature for December 6th.
“For 13 well-observed pulsars,
he has derived the present rates of
increase of period...
“The fastest changing pulsar is
NP 0532 in the Crab nebula....
“[But] Dr. Hunt calls particular
attention to CP 0808 in Camelopar-
dalis, whose period of 1.
seconds has shown no sign of
increase.... This confl icts with
Thomas Gold’s theory that the
energy radiated by a pulsar is
obtained at the expense of its rota-
tional energy.
“To Dr. Hunt, CP 0808 suggests
strongly that there must be another
source from which the radiated
energy is drawn, this source being
either the magnetic fi eld of the
object or else its gravitational
contraction.”
Add to this “glitches,” which
are occasional sudden speed-
ups observed in pulsars that are
otherwise slowing down. Astrono-
mers still struggle to model such
changes.ºJanuary 1995
Terrestrial Gamma Rays “The
Burst and Transient Source Experi-
ment (BATSE) aboard NASA’s
Compton Gamma Ray Observatory
was designed to study gamma-ray
bursts in space. Since its launch
in April 1991 it has recorded more
than 1,150 such events... But
BATSE has also detected more
than a dozen gamma-ray fl ashes
from the Earth. First dismissed
as spurious, these signals now
appear to be quite real and may be
associated with electromagnetic
discharges in our planet’s upper
atmosphere.
“Gerald J. Fishman (NASA-
Marshall Space Flight Center) and
his colleagues reported that seven
of the earthly gamma-ray fl ashes
occurred under the watchful eye
of a weather satellite, and in every
case there was a large thunder-
storm nearby. [Moreover,] airplane
pilots and astronauts have reported
seeing mysterious fl ashes of light
streaking upward from the tops of
thunderstorms....
“To produce [gamma rays], the
electric fi elds above storm clouds
would have to accelerate electrons
to energies of a million electron
volts, making them some 30 times
more powerful than the fi elds nor-
mally associated with lightning.”1945
1970
1995
75, 50 & 25 YEARS AGO by Roger W. Sinnott
close to Neptune. What a surprise! I
read the article again and followed the
link to Sky & Telescope’s Triton Tracker
app. After estimating the small dot’s
position angle and separation from
Neptune, it was clear that the small dot
was indeed Triton. Although I wasn’t
able to spot it with my eyes that night,
it was a surprisingly easy target for my
telescope and camera.
Karl-Ludwig Abken
Nordenham, Germany
Peace Offi cers in England
I confess to being a little bemused at
recent correspondence (S&T: Nov. 2019,
p. 6) regarding the potential danger
SUBMISSIONS: Write to Sky & Telescope, 90 Sherman St., Cambridge, MA 02140-3264, USA or email: letters@
skyandtelescope.org. Please limit your comments to 250 words; letters may be edited for brevity and clarity.FOR THE RECORD
- The caption for Messier 52’s image (S&T:
Oct. 2019, p. 32) should have stated that
158 million years is the cluster’s estimated
age; its distance is about 5,000 light-years. - “Transit Timetable” (S&T: Nov. 2019, p. 48)
correctly lists the event’s midpoint as 15:
Universal Time; the time-zone-specifi c mid-
points listed below it should also end in :20.
skyandtelescope.com • JANUARY 2020 7posed to astronomers by police offi cers
who might confuse the tube of a Dobso-
nian for something more sinister.
I have no wish to become politically
involved in the ongoing U.S. gun-
control debate, but I must say I am very
grateful to be an amateur astronomer
in England. We still do not have rou-
tinely armed police, and possession of a
handgun is 100% illegal here. The most
I might have to worry about is having
my night vision ruined by a fl ashlight-
wielding policeman who is unlikely to
be concerned about the possibility of mehaving any kind of weapon. It’s surely a
different world over there.
Harold Mead
Somerset, United Kingdom