Sky & Telescope - November 2019 - 35

his troops as "Old Stars" because of his fame as an astronomer - with protecting the Union army's left flank and capturing the railroad that served as a Confederate supply line
from the east. Mitchel undertook a rapid forced march and
captured Huntsville, Alabama, with its large depot and repair
station for the Memphis and Charleston Railroad line.
But most famous was Mitchel's role in enabling a daring raid intended to split the Confederacy and change the
course of the war. En route to Huntsville, a spy named J. J.
Andrews approached him with the idea of disabling a major
Confederate railroad that connected Marietta, Georgia,
with Chattanooga, Tennessee. Andrews's plan was to steal a
train, burn the bridges behind him, and, just south of Chattanooga, turn the train west and join Mitchel in Huntsville.
Mitchel supplied specially chosen troops. The Andrews Raiders made it to Marietta, stole a train and got away, but were
unable to burn any of the bridges because they were hotly
pursued for 87 miles in the legendary "Great Locomotive
Chase," immortalized in Buster Keaton's 1927 film The General and Walt Disney's 1956 suspense fi lm The Great Locomotive Chase. The raiders were caught, tried, and some were
hung, but after the war some of the survivors were awarded
the fi rst Medals of Honor.
In September 1862, Mitchel, by then promoted to Major
General, was reassigned to the Department of the South, in
Hilton Head, South Carolina, where he founded Mitchelville,
the first town deliberately designed for African-Americans
transitioning from slavery. The next month, on October 30th,
he died from yellow fever at the age of 53.

ANNALS OF THE DUDLE Y OBSERVATORY (186 6) / PUBLIC DO M AIN / COURTESY OF AU THOR

Mitchel as an Astronomer
In 2003, the late historian Donald E. Osterbrock described
Mitchel as "America's First Carl Sagan" (although more
accurately, Sagan should have been called "America's Second
O. M. Mitchel"). Like Sagan, Mitchel
was a gifted speaker whose astronomical lectures electrified a generation.
Like Sagan, Mitchel believed in the
possibility of life on other worlds. But
also like Sagan, Mitchel was a serious
research astronomer.
In June 1846, Mitchel found
that first-magnitude Alpha Scorpii
u PERFECT TIMING In the revolving-disk
electrochronograph Mitchel invented in late
1848, a make-circuit clock marked every
other second with a dot on a 22-inch paper
disk. At the end of every revolution, the
paper shifted and a new concentric circle
of dots began. The moment an astronomer
observed a star to be bisected by the vertical
wire in the eyepiece of a meridian telescope,
he pressed a telegraph key to make an additional mark on the revolving disk. In this way,
the time of the meridian transit was recorded
in relation to the dots that marked the time.

(Antares) had a faint, 5.5-magnitude companion star. In
October 1846, he became one of the first American astronomers to observe the planet Neptune after its discovery had
been announced. In October 1848, Mitchel participated in a
pioneering experiment using the telegraph to determine the
longitude of Cincinnati west of Philadelphia; for the experiment, Mitchel invented an electrochronograph, a mechanism
for simultaneously recording clock signals along with the
timings of observations; his design was adopted by several
observatories.
Less well known are Mitchel's systematic micrometrical measurements of double stars at declinations below the
celestial equator, performed at the direct request of the great
Russian astronomer Wilhelm Struve, founding director of
Pulkovo, who wanted to take advantage of both the Cincinnati telescope's large aperture and its more southerly latitude.
Also important were Mitchel's thousands of transit-telescope
observations of stellar positions for the U.S. Coast Survey. In
addition, The Sidereal Messenger was widely read by American astronomers, in part because Mitchel published his own
translations of French and German articles from foreign
journals, and reprinted correspondence surrounding the
discovery of Neptune.
Mitchel was recognized with honorary degrees and other
accolades. Among others, in 1846, he was offered the Rumford Professorship at Harvard University, which he declined
because he didn't want to relocate to Cambridge. In 1850,
he was one of the first five Americans elected to be a Foreign
Associate of the Royal Astronomical Society, and was elected
a member of the American Philosophical Society in 1853.
But Mitchel's most enduring legacy is probably his description of our Milky Way and other galaxies as "island universes." Although that marvelous image has been ascribed to
several 19th-century scientists, Mitchel was gifted in coining memorable turns of phrase. He
used the phrase "island universe" in
lectures and The Sidereal Messenger
numerous times as early as 1847
when describing research by Johann
Heinrich von Mädler, which Mitchel
translated from German.

¢ Contributing Editor TRUDY E. BELL,
formerly an editor for Scientific American and IEEE Spectrum and senior
writer for the University of California
High-Performance AstroComputing
Center, is author of a dozen books and
over 500 articles. Her journalism prizes
include the 2006 David N. Schramm
Award of the American Astronomical
Society. In 2017, asteroid (323552)
was named Trudybell 2004 TB in
recognition of her career. She can be
reached at t.e.bell@ieee.org.
sk yandtele scope.com * N OV E M B E R 2 019

35


http://www.skyandtelescope.com

Sky & Telescope - November 2019

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

Contents
Sky & Telescope - November 2019 - Cover1
Sky & Telescope - November 2019 - Cover2
Sky & Telescope - November 2019 - 1
Sky & Telescope - November 2019 - Contents
Sky & Telescope - November 2019 - 3
Sky & Telescope - November 2019 - 4
Sky & Telescope - November 2019 - 5
Sky & Telescope - November 2019 - 6
Sky & Telescope - November 2019 - 7
Sky & Telescope - November 2019 - 8
Sky & Telescope - November 2019 - 9
Sky & Telescope - November 2019 - 10
Sky & Telescope - November 2019 - 11
Sky & Telescope - November 2019 - 12
Sky & Telescope - November 2019 - 13
Sky & Telescope - November 2019 - 14
Sky & Telescope - November 2019 - 15
Sky & Telescope - November 2019 - 16
Sky & Telescope - November 2019 - 17
Sky & Telescope - November 2019 - 18
Sky & Telescope - November 2019 - 19
Sky & Telescope - November 2019 - 20
Sky & Telescope - November 2019 - 21
Sky & Telescope - November 2019 - 22
Sky & Telescope - November 2019 - 23
Sky & Telescope - November 2019 - 24
Sky & Telescope - November 2019 - 25
Sky & Telescope - November 2019 - 26
Sky & Telescope - November 2019 - 27
Sky & Telescope - November 2019 - 28
Sky & Telescope - November 2019 - 29
Sky & Telescope - November 2019 - 30
Sky & Telescope - November 2019 - 31
Sky & Telescope - November 2019 - 32
Sky & Telescope - November 2019 - 33
Sky & Telescope - November 2019 - 34
Sky & Telescope - November 2019 - 35
Sky & Telescope - November 2019 - 36
Sky & Telescope - November 2019 - 37
Sky & Telescope - November 2019 - 38
Sky & Telescope - November 2019 - 39
Sky & Telescope - November 2019 - 40
Sky & Telescope - November 2019 - 41
Sky & Telescope - November 2019 - 42
Sky & Telescope - November 2019 - 43
Sky & Telescope - November 2019 - 44
Sky & Telescope - November 2019 - 45
Sky & Telescope - November 2019 - 46
Sky & Telescope - November 2019 - 47
Sky & Telescope - November 2019 - 48
Sky & Telescope - November 2019 - 49
Sky & Telescope - November 2019 - 50
Sky & Telescope - November 2019 - 51
Sky & Telescope - November 2019 - 52
Sky & Telescope - November 2019 - 53
Sky & Telescope - November 2019 - 54
Sky & Telescope - November 2019 - 55
Sky & Telescope - November 2019 - 56
Sky & Telescope - November 2019 - 57
Sky & Telescope - November 2019 - 58
Sky & Telescope - November 2019 - 59
Sky & Telescope - November 2019 - 60
Sky & Telescope - November 2019 - 61
Sky & Telescope - November 2019 - 62
Sky & Telescope - November 2019 - 63
Sky & Telescope - November 2019 - 64
Sky & Telescope - November 2019 - 65
Sky & Telescope - November 2019 - 66
Sky & Telescope - November 2019 - 67
Sky & Telescope - November 2019 - 68
Sky & Telescope - November 2019 - 69
Sky & Telescope - November 2019 - 70
Sky & Telescope - November 2019 - 71
Sky & Telescope - November 2019 - 72
Sky & Telescope - November 2019 - 73
Sky & Telescope - November 2019 - 74
Sky & Telescope - November 2019 - 75
Sky & Telescope - November 2019 - 76
Sky & Telescope - November 2019 - 77
Sky & Telescope - November 2019 - 78
Sky & Telescope - November 2019 - 79
Sky & Telescope - November 2019 - 80
Sky & Telescope - November 2019 - 81
Sky & Telescope - November 2019 - 82
Sky & Telescope - November 2019 - 83
Sky & Telescope - November 2019 - 84
Sky & Telescope - November 2019 - Cover3
Sky & Telescope - November 2019 - Cover4
https://www.nxtbook.com/nxtbooks/aas/st_202405
https://www.nxtbook.com/nxtbooks/aas/st_202404_qr
https://www.nxtbook.com/nxtbooks/aas/st_202404
https://www.nxtbook.com/nxtbooks/aas/st_202403
https://www.nxtbook.com/nxtbooks/aas/st_202402
https://www.nxtbook.com/nxtbooks/aas/st_202401_aus
https://www.nxtbook.com/nxtbooks/aas/st_202401
https://www.nxtbook.com/nxtbooks/aas/st_202312_aus
https://www.nxtbook.com/nxtbooks/aas/st_202312
https://www.nxtbook.com/nxtbooks/aas/st_202311
https://www.nxtbook.com/nxtbooks/aas/st_202310
https://www.nxtbook.com/nxtbooks/aas/st_202309
https://www.nxtbook.com/nxtbooks/aas/st_202308
https://www.nxtbook.com/nxtbooks/aas/st_202307
https://www.nxtbook.com/nxtbooks/aas/st_202306
https://www.nxtbook.com/nxtbooks/aas/st_202305
https://www.nxtbook.com/nxtbooks/aas/st_202304
https://www.nxtbook.com/nxtbooks/aas/st_202304_qr
https://www.nxtbook.com/nxtbooks/aas/st_202303
https://www.nxtbook.com/nxtbooks/aas/st_202302
https://www.nxtbook.com/nxtbooks/aas/st_202301
https://www.nxtbook.com/nxtbooks/aas/st_202212
https://www.nxtbook.com/nxtbooks/aas/st_202211
https://www.nxtbook.com/nxtbooks/aas/st_202210
https://www.nxtbook.com/nxtbooks/aas/st_202209
https://www.nxtbook.com/nxtbooks/aas/st_202208
https://www.nxtbook.com/nxtbooks/aas/st_202207
https://www.nxtbook.com/nxtbooks/aas/st_202206
https://www.nxtbook.com/nxtbooks/aas/st_202205
https://www.nxtbook.com/nxtbooks/aas/st_202204
https://www.nxtbook.com/nxtbooks/aas/st_202203
https://www.nxtbook.com/nxtbooks/aas/st_202202
https://www.nxtbook.com/nxtbooks/aas/st_202201
https://www.nxtbook.com/nxtbooks/aas/st_202112
https://www.nxtbook.com/nxtbooks/aas/st_202111
https://www.nxtbook.com/nxtbooks/aas/st_202110
https://www.nxtbook.com/nxtbooks/aas/st_202109
https://www.nxtbook.com/nxtbooks/aas/st_202108
https://www.nxtbook.com/nxtbooks/aas/st_202107
https://www.nxtbook.com/nxtbooks/aas/st_202106
https://www.nxtbook.com/nxtbooks/aas/st_202105
https://www.nxtbook.com/nxtbooks/aas/st_202104
https://www.nxtbook.com/nxtbooks/aas/st_202103
https://www.nxtbook.com/nxtbooks/aas/st_202102
https://www.nxtbook.com/nxtbooks/aas/st_202101
https://www.nxtbook.com/nxtbooks/aas/skywatch_2021
https://www.nxtbook.com/nxtbooks/aas/st_202012
https://www.nxtbook.com/nxtbooks/aas/st_202011
https://www.nxtbook.com/nxtbooks/aas/st_202010
https://www.nxtbook.com/nxtbooks/aas/st_202009
https://www.nxtbook.com/nxtbooks/aas/st_202008
https://www.nxtbook.com/nxtbooks/aas/st_202007
https://www.nxtbook.com/nxtbooks/aas/st_202006
https://www.nxtbook.com/nxtbooks/aas/st_202005
https://www.nxtbook.com/nxtbooks/aas/st_202004
https://www.nxtbook.com/nxtbooks/aas/st_202003
https://www.nxtbook.com/nxtbooks/aas/st_202002
https://www.nxtbook.com/nxtbooks/aas/st_202001
https://www.nxtbook.com/nxtbooks/aas/st_201912
https://www.nxtbook.com/nxtbooks/aas/st_201911
https://www.nxtbook.com/nxtbooks/aas/st_201910
https://www.nxtbook.com/nxtbooks/aas/st_201909
https://www.nxtbook.com/nxtbooks/aas/st_201908
https://www.nxtbook.com/nxtbooks/aas/st_201907
https://www.nxtbook.com/nxtbooks/aas/st_201906
https://www.nxtbook.com/nxtbooks/aas/st_201905
https://www.nxtbook.com/nxtbooks/aas/st_201904
https://www.nxtbook.com/nxtbooks/aas/st_201903
https://www.nxtbook.com/nxtbooks/aas/st_201902
https://www.nxtbook.com/nxtbooks/aas/st_201901
https://www.nxtbook.com/nxtbooks/aas/st_201812
https://www.nxtbook.com/nxtbooks/aas/st_201811
https://www.nxtbook.com/nxtbooks/aas/st_201810
https://www.nxtbook.com/nxtbooks/aas/st_201809
https://www.nxtbook.com/nxtbooks/aas/st_201808
https://www.nxtbook.com/nxtbooks/aas/st_201807
https://www.nxtbook.com/nxtbooks/aas/st_201806
https://www.nxtbook.com/nxtbooks/aas/st_201805
https://www.nxtbook.com/nxtbooks/aas/st_201804
https://www.nxtbook.com/nxtbooks/aas/st_201803
https://www.nxtbook.com/nxtbooks/aas/st_201802
https://www.nxtbook.com/nxtbooks/aas/st_201801
https://www.nxtbook.com/nxtbooks/aas/st_201712
https://www.nxtbook.com/nxtbooks/aas/st_201711
https://www.nxtbook.com/nxtbooks/aas/st_201710
https://www.nxtbook.com/nxtbooks/aas/st_201709
https://www.nxtbook.com/nxtbooks/aas/st_201708
https://www.nxtbook.com/nxtbooks/aas/st_201707
https://www.nxtbook.com/nxtbooks/aas/st_201706
https://www.nxtbook.com/nxtbooks/aas/st_201705
https://www.nxtbook.com/nxtbooks/aas/st_201704
https://www.nxtbook.com/nxtbooks/aas/st_201703
https://www.nxtbook.com/nxtbooks/aas/st_201702
https://www.nxtbook.com/nxtbooks/aas/st_201701
https://www.nxtbook.com/nxtbooks/aas/st_201612
https://www.nxtbook.com/nxtbooks/aas/st_201611
https://www.nxtbook.com/nxtbooks/aas/st_201610
https://www.nxtbook.com/nxtbooks/aas/st_201609
https://www.nxtbook.com/nxtbooks/aas/st_201608
https://www.nxtbook.com/nxtbooks/aas/st_201607
https://www.nxtbook.com/nxtbooks/aas/st_201606
https://www.nxtbook.com/nxtbooks/aas/st_201605
https://www.nxtbook.com/nxtbooks/aas/st_201604
https://www.nxtbook.com/nxtbooks/aas/st_201603
https://www.nxtbook.com/nxtbooks/aas/st_201602
https://www.nxtbook.com/nxtbooks/aas/st_201601
https://www.nxtbook.com/nxtbooks/aas/st_201512
https://www.nxtbook.com/nxtbooks/aas/st_201511
https://www.nxtbook.com/nxtbooks/aas/st_201510
https://www.nxtbook.com/nxtbooks/aas/st_201509
https://www.nxtbook.com/nxtbooks/aas/st_201508
https://www.nxtbook.com/nxtbooks/aas/st_201507
https://www.nxtbook.com/nxtbooks/aas/st_201506
https://www.nxtbook.com/nxtbooks/aas/st_201505
https://www.nxtbook.com/nxtbooks/aas/st_201504
https://www.nxtbook.com/nxtbooks/aas/st_201503
https://www.nxtbook.com/nxtbooks/aas/st_201502
https://www.nxtbook.com/nxtbooks/aas/st_201501
https://www.nxtbook.com/nxtbooks/aas/st_201412
https://www.nxtbook.com/nxtbooks/aas/st_201411
https://www.nxtbook.com/nxtbooks/aas/st_201410
https://www.nxtbook.com/nxtbooks/aas/st_201409
https://www.nxtbook.com/nxtbooks/aas/st_201408
https://www.nxtbook.com/nxtbooks/aas/st_201407
https://www.nxtbook.com/nxtbooks/aas/st_201406
https://www.nxtbook.com/nxtbooks/aas/st_mars
https://www.nxtbook.com/nxtbooks/aas/st_201405
https://www.nxtbook.com/nxtbooks/aas/st_201404
https://www.nxtbook.com/nxtbooks/aas/st_201403
https://www.nxtbook.com/nxtbooks/aas/st_201402
https://www.nxtbook.com/nxtbooks/aas/st_201401
https://www.nxtbook.com/nxtbooks/aas/st_201312
https://www.nxtbook.com/nxtbooks/aas/st_201311
https://www.nxtbook.com/nxtbooks/aas/st_201310
https://www.nxtbook.com/nxtbooks/aas/st_201309
https://www.nxtbook.com/nxtbooks/aas/st_201308
https://www.nxtbook.com/nxtbooks/aas/st_201307
https://www.nxtbook.com/nxtbooks/aas/st_201306
https://www.nxtbook.com/nxtbooks/aas/st_201305
https://www.nxtbook.com/nxtbooks/aas/st_201304
https://www.nxtbook.com/nxtbooks/aas/st_201303
https://www.nxtbook.com/nxtbooks/aas/st_201302
https://www.nxtbook.com/nxtbooks/aas/st_201301
https://www.nxtbook.com/nxtbooks/aas/st_201212
https://www.nxtbook.com/nxtbooks/aas/st_201211
https://www.nxtbook.com/nxtbooks/aas/st_201210
https://www.nxtbook.com/nxtbooks/aas/st_201209
https://www.nxtbook.com/nxtbooks/aas/st_201208
https://www.nxtbook.com/nxtbooks/aas/st_201207
https://www.nxtbook.com/nxtbooks/aas/st_201206
https://www.nxtbook.com/nxtbooks/aas/st_201205
https://www.nxtbook.com/nxtbooks/aas/st_201204
https://www.nxtbook.com/nxtbooks/aas/st_201203
https://www.nxtbook.com/nxtbooks/aas/st_201202
https://www.nxtbook.com/nxtbooks/aas/st_201201
https://www.nxtbook.com/nxtbooks/aas/st_201112
https://www.nxtbook.com/nxtbooks/aas/st_201111
https://www.nxtbook.com/nxtbooks/aas/st_201110
https://www.nxtbook.com/nxtbooks/aas/st_201109
https://www.nxtbook.com/nxtbooks/aas/st_201108
https://www.nxtbook.com/nxtbooks/aas/st_201107
https://www.nxtbook.com/nxtbooks/aas/st_201106
https://www.nxtbook.com/nxtbooks/aas/st_201105
https://www.nxtbook.com/nxtbooks/aas/st_201104
https://www.nxtbook.com/nxtbooks/aas/st_201103
https://www.nxtbook.com/nxtbooks/aas/st_201102
https://www.nxtbook.com/nxtbooks/aas/st_201101
https://www.nxtbook.com/nxtbooks/aas/st_201012
https://www.nxtbook.com/nxtbooks/aas/st_201011
https://www.nxtbook.com/nxtbooks/aas/st_201010
https://www.nxtbook.com/nxtbooks/aas/st_201009
https://www.nxtbook.com/nxtbooks/aas/st_201008
https://www.nxtbook.com/nxtbooks/aas/st_201007
https://www.nxtbook.com/nxtbooks/aas/st_201006
https://www.nxtbook.com/nxtbooks/aas/st_201005
https://www.nxtbook.com/nxtbooks/aas/st_201004
https://www.nxtbook.com/nxtbooks/aas/st_201003
https://www.nxtbook.com/nxtbooks/aas/st_201002
https://www.nxtbook.com/nxtbooks/aas/st_201001
https://www.nxtbookmedia.com