Sky and Telescope - October 2017 - 8

From Our Readers

Whither "Tabby's Star"?
Why isn't "Tabby's Star" (S&T: June
2017, p. 16) called "copernicus123's
star"? The article seems to give credit to
the latter, a citizen scientist, for being
the ﬁrst to note the unusual dip in light
emanating from KIC 8462852. I ask this
in light of the article in the same issue
about assigning credit for the discovery
of M57. There the authors put a lot of
work into studying the available sources
to decide whether Charles Messier or
Antoine Darquier should be credited
with being the ﬁrst to observe and
describe the Ring Nebula.
Bob Rosenstein
Ellicott City, Maryland

Monica Young replies: Most stars

don't have common names, at least
not ofﬁcial ones recognized by the IAU, but
instead are referred to by catalog numbers.
In this case, "Tabby's Star" is ofﬁcially
designated KIC 8462852 (for Kepler Input
Catalog), and that's how astronomers refer

to it. That said, well-studied objects do lend
themselves to common names, and those
are often the names of their discoverers.
It's true that copernicus123 ﬁrst noted that
this star's light curve displayed a "bizarre
peak - a giant transit." However, numerous
scientists as well as citizen scientists had
already examined the Kepler observations,
even if only as part of a larger dataset. As
important as the comment from copernicus123 was in pointing out the star's unusual nature, it can't be said that he discovered
the star itself.
Moreover, what was essential to
understanding the star's unusual nature
was not just the single dip spotted by
copernicus123 but rather all of its dips
and weird behavior. It wasn't until Tabetha
Boyajian and her colleagues published
their "Where's the Flux?" paper that this all
came together. (It's worth noting that she
did not name the star after herself.)

1967

1992

º October 1942
Crab Nebula "The rate of expansion of the Crab nebula is so great
that, within an astronomically brief
interval, perhaps by 3000 A.D., the
material of which it is composed
must become so tenuous that it
cannot perceptibly shine. It is very
likely that the entire episode of the
Chinese nova [the supernova of
A.D. 1054] and its sequel, so far
as it can be perceived from the
earth, has taken place in an interval shorter than the 4,000 years
required by its light to reach us.
The story of the Crab nebula, therefore, may well have ended centuries before it seemed to begin, and
in the interim was carried secretly
by the light waves spreading in
ever-increasing spheres from the
place of the outburst."
This lavish summation by John
C. Duncan (Wellesley College)
still holds, though the Crab is now
thought to be about 6,500 lightyears away.

O C T O B E R 2 0 17 * S K Y & T E L E S C O P E

Thanks for the update on the Maunder
Minimum (S&T: June 2017, p. 9). Since
science has not been able to afﬁrm
that the abnormally cold temperatures
recorded in Europe during that 70-year
period were related to the corresponding lull in solar activity, I wonder what
researchers will conclude if temperatures once again recede during Cycle
25. Perhaps they'll debate whether solar
inactivity is merely temporarily masking
the underlying global-warming data.
Bill Zuna
Tallahassee, Florida

FOR THE RECORD

* In the diagram listing elementary particles found in physics' Standard Model
(S&T: Aug. 2017, p. 30), the particle labeled
"t" is the Top (not Tau) quark.

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
1942

A New Maunder Minimum?

º October 1967
Lopsided Moon "Despite the enormous labor and care that generations of mathematical astronomers
have devoted to the moon's orbital
motion, small but puzzling discrepancies between observation and
theory continue to arise. . . .
"Recently, at the Royal Greenwich Observatory in England, an
analysis of occultations observed
in 1958 and 1959 revealed a cyclic
discrepancy [in the Moon's orbital
latitude, up to] a large fraction of a
second of arc, even after corrections for lunar limb irregularities
have been applied. . . . The cause
of the fluctuations is uncertain.
[Perhaps] the lunar center of mass
deviates from its center of figure."
Indeed it does, a ﬁnding that
has led to adjustments in solareclipse predictions and the way
lunar elevations are deﬁned.
º October 1992
CCD Era Begins "On one of my
first nights using the [Santa Barbara
Instrument Group] ST-6, I had it

mounted on an 11-inch Celestron
telescope and ready to go less than
an hour after sunset. [Aided by] setting circles, I swung the telescope
in the direction of the open star
cluster M67 deep in the western
twilight. Nothing was visible through
an 8 × 50 finder, [but nevertheless] I
took a 10-second exposure.
As the ST-6 image swept down
the computer screen, my jaw
dropped. Hundreds of sparkling
suns splashed across the field, the
three faintest ones being an incredible magnitude 15.7. All this from an
image made in a sky too bright to
show the cluster visually! . . .
"The ST-6 should blow open the
door to deep-sky CCD imaging by
amateurs. Nothing else in its price
range can offer the same level of
performance."
Not long after Dennis di Cicco's
glowing review, Sky Publishing
launched a separate magazine, CCD
Astronomy, to explore the ways
amateurs could beneﬁt from electronic imaging. It came out quarterly
from early 1994 through early 1997.

Sky and Telescope - October 2017

Table of Contents for the Digital Edition of Sky and Telescope - October 2017