Sky & Telescope - March 2019 - 7

another of Herschel's many amazing
observations based solely on the visual
appearance of objects in his telescopes.
James Mullaney
Rehoboth Beach, Delaware

Scaling the Void
Great article on the Local Void (S&T:
Oct. 2018, p. 12)! But like all huge
structures, I had difﬁculty visualizing it,
so I tried scaling.
Make 1 million light-years equal 1
meter (3 feet): The Milky Way is now
a disk 9 cm (3.6 inches) wide. If you're
facing the Local Void with the Milky
Way in front of you, Andromeda is off
to your left 2.5 meters, a disk about 20
cm wide. M33, the Triangulum Galaxy,
is a 2.5-cm disk to the left and below
Andromeda, about 1 meter from it.
Have a friend hold the Milky Way
while you go 1.5 meters past it and you
pass Barnard's Galaxy (NGC 6822).
Go another 2 meters and you pass the
Sagittarius Dwarf Irregular Galaxy.

Now for another 250 meters you walk
through completely empty space.
Look back when you reach the end of
the Local Void, and the Milky Way and
Andromeda are very small and faint.
I've written an article using the
solar system model in front of Grifﬁth
Observatory to show how far away the
Oort Cloud and Alpha Centauri are.
When you use my scale for the Local
Void on this model, you come to realize
just how large the void really is.
Dave Nakamoto
Azusa, California

Moonset Moment
Eli Maor's justiﬁably reverent Focal
Point (S&T: Dec. 2018, p. 84) overlooks
the profound inspiration that humankind's ﬁrst crewed visit to another world
gave to my baby boomer generation.
I vividly remember that Christmas

1969

1994

Daniel Costanzo
Locust Grove, Virginia

FOR THE RECORD

* In "New Year's Eve Celestial Celebration"
(S&T: Dec. 2018, p. 22), the actual distance
for Altair is 17 light-years.

* In Gallery (S&T: Jan. 2019, p. 76), Nebula
CTB-1 should be 36 arcminutes in diameter.

SUBMISSIONS: Write to Sky & Telescope, 90 Sherman St., Cambridge, MA 02140-3264, U.S.A. or email: letters@
skyandtelescope.com. Please limit your comments to 250 words; letters may be edited for brevity and clarity.

75, 50 & 25 YEARS AGO by Roger W. Sinnott
1944

Eve in 1968 when Apollo 8's crew gave
the ﬁrst-ever "Live from the Moon"
television broadcast. While the Moon's
magniﬁcently desolate features scrolled
across my family's black-and-white TV
screen and the astronauts read from the
Book of Genesis, I looked out my window and saw the actual Moon setting
outside in the wintry night.
So, besides the Apollo 8 crew's
iconic Earthrise moment, my Moonset
moment brought a little boy a profound
awareness of our place in the universe.

º March 1944
Titan's Air "Titan [is] the principal satellite of Saturn. . . . Late
in January, Dr. Gerard P. Kuiper
. . . reported from the McDonald
Observatory in Texas that he had
obtained spectra of Titan in red
and infrared light. These spectra
reveal an atmosphere rich in hydrogen. It is much like the atmosphere
of Saturn itself, containing methane
(marsh gas) and possibly ammonia.
. . . Life, as we know it, is as much
out of the question on Titan as on
Saturn."
We now know Titan's atmosphere is largely nitrogen, but it
does have some methane. Dorrit
Hofﬂeit's ﬁnal remark also needs a
different emphasis. Astrobiologists
think Titan could well harbor some
exotic form of life.
º March 1969
Missing Mass "A major discrepancy arises when astronomers try
to determine the mass of a cluster

of galaxies. Such a cluster is
equivalent to more than 100 million
million suns. The system's mass
can be calculated from the motions
of the galaxies in it, but when the
individual masses of the member
galaxies are added up, the sum is
more than 10 times smaller! . . .
"This had been discovered for
the giant cluster in Coma Berenices
by Fritz Zwicky in 1933. [And at a
1961 meeting of astronomers in]
Santa Barbara, cluster after cluster
- both large and small - was
added to the list."
The curiosities cited by Herbert
J. Rood (Van Vleck Observatory),
plus other lines of evidence, have
grown into the major cosmological
problem of "dark matter."
º March 1994
Big Bang, or . . . ? "The gauntlet
thrown, Sky & Telescope's challenge to rename the Big Bang
immediately struck a chord
among the public. [In the end we]
processed 13,099 entries from
persons in 41 countries. . . .

"Creation was submitted 124
times, followed closely by Cosmogenesis. . . . Damaru (the Hindu
drum of creation) was suggested.
. . . Those opting for modern-day
English often resorted to terms
that evoked a certain awe or
puzzlement. A 90-year-old entrant
submitted Out of the Misty Mystery.
. . . But some contestants, and not
just the professional astronomers,
had a good grasp of the standard
model. They pictured the universe
as an expanding entity with such
titles as Super Seed, . . . Hawking's
Hunch, Planck Point, and Hubble
Bubble. . . . And then there was
Bertha D. Universe. . . .
"A small minority thought they
might influence judges Timothy
Ferris, Hugh Downs, and Carl
Sagan [with a name like] BS (Before
Sagan). . . ."
Sagan had predicted that no
one would be clever enough to
outdo Fred Hoyle's ﬂawed and
sarcastic term, Big Bang. And the
judges' ﬁnal verdict turned out to
be: Leave it alone!
sk yandtele scope.com * M A RCH 2 019

http://www.skyandtelescope.com

Sky & Telescope - March 2019

Table of Contents for the Digital Edition of Sky & Telescope - March 2019