Sky & Telescope - August 2023 - 7

(S&T: May 2023, p. 34). I noted that the
planets' orbital alignment must be just
so for astronomers to detect them.
It's hard to fathom that so many
star systems are exquistely aligned for
detecting planetary transits. How can
so many of them be lined up so perfectly?
Perhaps they are arranged that
way from being part of the Milky Way?
Can one speculate on what proportion
of stars not properly aligned for planetary
detection could harbor planets?
Robert Pellenbarg
Berlin, Maryland
Monica Young replies: It is statistically
unlikely for a planet to be
transiting its star from our perspective. How
likely it is depends on a number of factors,
including the size of the star, the size of the
planet, how close the planet is to its star,
and the distance of the star from Earth.
Such calculations have been done for the
larger population of planets in the Milky
Way, and those estimates say that for every
"
transiting planet we see, there are 10 or
maybe even 100 more. If you're only looking
at close-in planets, the likelihood of catching
transits is higher, with every transiting planet
standing in for two or three that are not.
Applause For Emily
I want to compliment the editors of
S&T regarding two superb articles written
by Emily Lakdawalla: " Rock On "
(S&T: Feb. 2022, p. 12) and " Venus
Renaissance " (S&T: May 2022, p. 12).
I'm not in the habit of writing to magazines
regarding articles I've read, but
I feel it is my duty to give you feedback
on a job well done.
I've been a highly satisfied subscriber
to S&T for many years. I initially
noticed the outstanding input of
Emily Lakdawalla from her articles in
The Planetary Report magazine. Aware
that she was amongst the contributing
editors of S&T, I took special interest
in her February and May 2022 contributions
and was pleased to find that
both articles are further examples of
her outstanding science-writing skill.
I'm therefore hopeful that you're aware
of the treasure you have amongst your
authors, and I look forward to more of
her insight and brilliant features.
Martin Lee Collin
Tel Aviv, Israel
FOR THE RECORD
* Although Ulugh Beg's star catalog was
a significant improvement on Ptolemy's,
its average accuracy was nowhere near as
good as that of Tycho Brahe's star catalog,
unlike what was stated in " The Past and Future
of Star Names " (S&T: May 2023, p. 26).
* In April's Sky at a Glance (S&T: Apr.
2023, p. 41), the new Moon occurred at
4:13 UT on April 20th.
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
1948
1973
1998
º August 1948
Poor Reception " Radio engineers
have noted that three or four
days after new or full moon the
usable bands of frequencies for
short-wave broadcasts to distant
stations are slightly narrower than
at other times. This effect has
been associated with the tideproducing
action of the moon on
the ionospheric layers of the earth's
atmosphere. . . . The sun first plays
its role by ionizing the atmosphere
on the earth's sunlit side. Currents
flow in this ionized atmosphere,
and are modified by the tidal
effects of the moon. This tends
to lessen the ion density, thereby
reducing the highest frequency that
can be used for broadcasts. "
º August 1973
Before ISS " Thousands of persons
[on May 14th] viewed the
historic launch of the American
space station, Skylab . . . From the
observer's viewpoint, however, the
Skylab spectacular became most
exciting eight hours later . . .
" David Shipano tells the story:
'Joe Steed and I [went to the Fernbank
Science Center, Atlanta.] At
about 9:42 p.m. EDT a bright object
was seen about 60° high in Leo . . .
Well, so much for Skylab, I thought.
" 'Suddenly, someone shouted,
'Hey, there's another one!' At the
place where the first object had
appeared, I saw not one but two
traveling together, about three
degrees apart. Then came No. 4,
followed by another pair. In all, the
Fernbank observers saw seven
bodies, of which No. 4 turned out to
be the space laboratory itself. The
first was [the Saturn rocket] second
stage, the last the meteoroid shield
that had torn loose, and the other
four were parts of the nose-cone
protective shroud. To put it mildly,
we had seen some show!' "
º August 1998
The End " Our society is steeped in
the uneasy awareness that human
extinction is possible. Nuclear
Armageddon, ecological catastrophes,
and mutant viruses are
among the near-term doomsday
prospects thrust forward by the prudent,
the paranoid, and the profitminded.
In the longer run we fear
such astronomical events as asteroid
or comet impacts and galactic
gamma-ray bursts. . . . But can life
outlast the stars themselves? . . .
" Whether life can exist indefinitely,
or whether the universe is
structured to guarantee the final
annihilation of all consciousness,
purpose, and meaning - including
any record . . . - holds an
inordinate fascination. "
So astrophysicists Fred Adams
and Gregory Laughlin conclude
their peek into the far future, having
taken us through what they call the
Stelliferous Era (the present), the
Degenerate Era (100 trillion years to
come, when all stars are dead), the
Black Hole Era (perhaps 1037 years
ahead), and beyond. Classics like
this article are a good reason to
save your back issues!
sk yand tele scope .o r g * AUGUST 2023
7

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